A pilot study for Basidiomycete-associated chronic cough: A potential contributor to refractory and unexplained or refractory chronic cough

A pilot study for Basidiomycete-associated chronic cough: A potential contributor to refractory and unexplained or refractory chronic cough | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article A pilot study for Basidiomycete-associated chronic cough: A potential contributor to refractory and unexplained or refractory chronic cough Jun Iriki, Takahiro Takazono, Yasushi Obase, Yuka Nagae, Susumu Fukahori, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7568485/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Recent evidence suggests a potential association between chronic cough and environmental fungi, particularly basidiomycetes, giving rise to the concept of fungus-associated chronic cough (FACC). However, the role of basidiomycetes in chronic cough remains poorly understood. In this pilot study, we investigated 30 patients with unexplained or refractory chronic cough (UCC/RCC) and 30 patients with other respiratory diseases (non-chronic cough). Spontaneous sputum samples were collected for fungal culture, and participants completed a cough and sputum symptom questionnaire, underwent chest computed tomography, and were evaluated for underlying diseases and medication use. Analyses were conducted by chronic cough status and by basidiomycete detection. Basidiomycetes were detected in the sputum of 9 out of 30 chronic cough patients but in none of the non-chronic cough patients (P = 0.0019), with a significant seasonal peak from June to August (P = 0.0419). No associations were observed with age, sex, underlying diseases, cough severity, or high-resolution computed tomography findings. These results indicate that basidiomycete colonization may contribute to FACC in individuals with UCC/RCC, particularly during the summer months. Health sciences/Diseases Health sciences/Medical research Biological sciences/Microbiology fungus-associated chronic cough chronic cough of unknown cause treatment-resistant chronic cough basidiomycete fungi culture Figures Figure 1 Figure 2 Introduction Coughing is a biological defense response to expel foreign substances and secretions from the airways. Chronic cough is defined as a cough that persists for 8 weeks or longer. 1 2 In Japan, asthma-related cough is the most common cause of chronic cough; other common causes include atopic cough, gastroesophageal reflux disease, sino-bronchial syndrome, and post-infectious cough. 3 4 5 Unexplained chronic cough (UCC) or refractory chronic cough (RCC) may also occur even with appropriate treatment of the underlying disease. Although several drug therapies, such as pregabalin 6 and P2X3 receptor antagonists, 7 have shown efficacy, an appropriate treatment algorithm for UCC/RCC has not been sufficiently validated. In 2009, Ogawa et al. reported a new disease called “fungus-associated chronic cough” (FACC). 8 FACC is defined as chronic cough in patients from whom environmental fungi are cultured in sputum and treated with a low dose of itraconazole. Basidiomycetes such as Bjerkandera adusta are considered the most important environmental fungi in the FACC. Despite conventional cough treatments, FACC does not improve, and patients with UCC/RCC may include those with FACC. 9 However, these studies were limited to a single institution. The accurate detection of basidiomycetes in clinical specimens is challenging and there is no consensus on the laboratory method for their detection in airway samples. Consequently, the exact prevalence remains unknown. In addition, basidiomycetes are detected year-round in outdoor or indoor environments but are more frequently detected in summer. 10 11 12 It has also been reported that the abundance of basidiomycetes is affected not only by temperature but also by humidity, 13 14 and there is a possibility that the onset of FACC is also seasonal. Ogawa et al. subsequently reported additional cases suggestive of FACC; 15 16 however, the number of such cases was insufficient, and the sensitivity and specificity of the isolation and culture methods for basidiomycetes remain unknown. Therefore, it cannot be definitively stated that basidiomycetes in the airways cause chronic coughing or its subsequent pathogenesis. In the present pilot study, we aimed to investigate the reproducibility of findings related to FACC in a region different from that previously reported. Specifically, we performed fungal cultures of sputum from patients with UCC/RCC to determine whether basidiomycetes could be isolated in Nagasaki. Additionally, we compared the background factors of patients with chronic cough in whom basidiomycetes were detected. Results Participant Characteristics Sixty patients participated in the study and were divided into two groups: the CC group (n = 30) and the NC group (n = 30). Sputum samples were collected through self-expectoration from all participants. Table 1 summarizes the clinical characteristics of the study participants. Age did not differ significantly between the two groups (68.0 (10.2) years vs. 66.2 (12.9) years). In the CC group, there were seven males and 23 females, while the NC group had 14 males and 16 females (P = 1.000). Smoking history was present in 11 patients in the CC group and 20 in the NC group (P = 0.201). In the CC group, underlying diseases included bronchial asthma (22 patients), COPD (3), sinusitis (including sinus bronchial syndrome; 8), gastroesophageal reflux disease (2), and a history of thyroid tumor surgery (3). Two patients had UCC, and 28 patients had RCC that did not respond to treatment. In the NC group, 29 patients had lung tumors (16 adenocarcinomas, 6 small-cell carcinomas, 2 thymomas, 1 malignant scleral mesothelioma, 1 pulmonary artery vascular sarcoma, and 3 unknown histology). Among them, six had interstitial lung disease and five had COPD. One case of radiation pneumonitis was observed; however, there were no cases of bronchial asthma. In the CC group, 22 patients received regular inhaled steroids, 11 received macrolide antibacterial agents, and 2 received amphotericin B oral solution. In the NC group, one patient received tetracyclines. Fungal culture results showed that basidiomycetes were detected in 9 of CC group, whereas none were detected in NC group (P = 0.0019). Identification of Basidiomycetes in Sputum Cultures Genetic analysis showed that the genera such as Irpex ( Irpex laceratus and Emmia lacerata ) were detected in five cases; Phanerochaete in three; Phanerodontia and Trametes in two; Bjerkandera , Ceriporia , Crepatura , Perenniporia , Phlebia , and Rigidoporus in one (Table 2). In addition to basidiomycetes, Penicillium were detected in four cases, each of Phomopsis and Crepatura ellipsospora were detected in one case (Supplement). Monthly Number of Sputum Collection and Basidiomycetes Positivity and Monthly Humidity Average in Nagasaki City Figure 1 illustrates the monthly number of sputum collections, Basidiomycetes positivity, and average monthly humidity and temperature in Nagasaki. Basidiomycetes were not detected in sputum collected during the winter months from November to February. The monthly humidity average in Nagasaki correlated with the monthly detection rate of basidiomycetes in CC group (P = 0.0039, R 2 = 0.58; Fig. 2A). Similarly, the average monthly temperature was also correlated with the monthly detection rate of basidiomycetes in the CC group (P = 0.0073, R2 = 0.53; Fig. 2B). Background Comparison of Patients with Chronic Cough: Sputum Basidiomycetes Detected vs. Not Detected Table 3 compares the background characteristics of patients with chronic cough with and without basidiomycetes detected in sputum. Among patients with chronic cough, there were no significant differences in age, sex, smoking history, use of antibacterial and antifungal agents, inhaled steroids, proton pump inhibitor or comorbidities (bronchial asthma, COPD, sinusitis, or reflux esophagitis) between the patients detected and not detected basidiomycetes. No significant differences were seen in VAS and CAT scores. High-resolution computed tomography (HRCT) of the lungs at the time of sputum collection revealed cavitary lesions, bronchiectasis, and mucus plugs in some cases; however, no significant differences were seen between the two groups. About the timing of specimen collection, basidiomycetes were significantly more frequently detected in specimens collected between June and August (P = 0.0419). Of the nine cases basidiomycetes were detected in, two or more species were detected in four cases, but the background factors mentioned above did not differ from the other five cases (data not shown). Discussion The primary results of this study were as follows: basidiomycetes were detected in the sputum of 9 of 30 patients with chronic cough, while no basidiomycetes were found in 30 patients with non-chronic cough (P = 0.0019). Additionally, basidiomycetes were detected only in sputum samples collected between June and August (P = 0.0419). Our study, conducted in a different region than previously reported, found no basidiomycetes in patients with non-chronic cough. Thirty percent of the patients with chronic cough had basidiomycetes in their sputum. Previous reports have implicated basidiomycetes, including B. adusta , in airway colonization in patients with airway lesions, such as bronchial asthma, COPD, chronic sinusitis, and interstitial pneumonia. 17 18 19 20 In our study, basidiomycetes were detected in five patients with bronchial asthma, three with chronic sinusitis, and one with COPD, suggesting that some patients with chronic cough may have basidiomycete colonization and be diagnosed with RCC. Although there were no significant differences in use of inhaled steroids between the patients detected and not detected basidiomycetes, it is necessary to increase the sample size and continue the study. A previous report found B. adusta in 14 of 31 patients with fungal allergic bronchopulmonary aspergillosis (FACC), and other basidiomycetes in 17 patients. 21 However, reports on the types and frequencies of other basidiomycete species are scarce. In our study, we detected 10 genera of the phylum Basidiomycota, with Irpex being the most frequently isolated and Bjerkandera detected in only one case. Although Bjerkandera is reported to be more frequently detected outdoors compared with Cladosporium , Penicillium , Alternaria , and Aspergillus , 22 the species isolated from different regions may vary. Basidiomycetes, such as B. adusta , have been implicated as causative antigens in allergic bronchopulmonary mycosis. 23 Fifteen percent of patients with chronic cough with detected basidiomycetes had mucus plugs in the bronchioles based on HRCT findings. 24 In our study, mucous plugs were found in the peripheral airways of two of nine patients (22.2%) with detected basidiomycetes. Previous reports suggested allergic cough due to basidiomycetes sensitization based on increased eosinophils in sputum of patients with FACC and the results of bronchial provocation and lymphocyte stimulation tests using B. adusta antigen solution. 25 However, in our study, we used self-expectorated sputum rather than induced sputum for culture testing, and we did not use the Miller & Jones or Geckler classifications, so the quality of the sputum samples varied, and the basidiomycetes detected may have been established in the upper respiratory tract, including the pharyngeal mucosa. Our study did not evaluate eosinophils in sputum, and no report has definitively verified this association. Further interventional studies are needed to elucidate the pathogenesis of chronic cough in patients with basidiomycosis, including antifungal agent administration and reexamination of sputum cultures after symptom improvement. B. adusta is widely distributed indoors and outdoors globally but is mainly detected in summer. 10 In the present study, no basidiomycetes were detected in samples collected during winter. Additionally, humidity correlated with the detection rate of basidiomycetes. Our results may suggest that basidiomycetes cause chronic coughing, especially during summer. In our study, no antifungal drugs were administered to patients with basidiomycosis, and there was no seasonal variation in cough symptoms in cases where basidiomycosis was detected. As there have been no previous reports of seasonal variation in cough symptoms in patients diagnosed with FACC, it is necessary to conduct follow-up surveys of patients where basidiomycosis was detected. Since basidiomycetes are rarely detected in microbiological sputum examinations in general medical facilities, cases of FACC may be overlooked. In patients with chronic cough unresponsive to appropriate treatment, sputum culture using fungal medium should be considered with FACC in mind. The limitations of this pilot study included the small sample size, timing of specimen collection, and bias in comorbidities. Additionally, a causal relationship between basidiomycetes isolation and symptoms has not been proven. Large-scale observational studies and interventional trials are needed to evaluate symptom improvement following antifungal treatment. Conclusion In Nagasaki, a region distinct from those previously reported, basidiomycetes were detected in the sputum of 30% of patients with chronic cough, while they were entirely absent in patients without chronic cough. The correlation between season and humidity with the frequency of basidiomycete identification indirectly underscores the clinical significance of fungal airway colonization and contamination. Methods Study Design Between June 1, 2022, and March 31, 2024, patients with UCC/RCC who live in Nagasaki City and visited our respiratory medicine outpatient clinic or were admitted to the respiratory medicine department at our institution were included in the chronic cough group (CC group). Spontaneous sputum samples were collected from these patients after obtaining their consent. Additionally, patients admitted to our department for the examination or treatment of respiratory diseases (such as lung cancer or interstitial pneumonia) were included in the non-chronic cough group (NC group). These patients had no cough symptoms or obvious airway infections and were able to provide sputum samples. Patients with a performance status of 3 or higher, poor general condition, or difficulty in self-expectorating were excluded from the study. The collected sputum samples were subjected to fungal cultures on the same day. This single-center, prospective, observational study was conducted in accordance with the ethical standards outlined in the Declaration of Helsinki. The study protocol was approved by the Ethics Committee of our institution (Approval No. 23091101). Diagnosis of Chronic Cough According to the 2019 guidelines of the Japanese Respiratory Society for the treatment of cough and sputum, patients with persistent cough symptoms lasting for more than 8 weeks are diagnosed with chronic cough. 1 UCC refers to chronic coughing of unknown origin that persists despite adequate treatment, including empiric therapy. chronic cough that does not improve even with appropriate treatment for conditions such as cough asthma and gastroesophageal reflux disease is referred to as RCC. 26 Mycological Study Sputum samples collected from the patients were applied to Sabouraud dextrose agar (210950, Becton, Dickinson and Company, BD, Tokyo, Japan) and incubated at 30 °C for 2 weeks. Emergent basidiomycete colonies were isolated on potato dextrose agar (213400, BD Biosciences) and cultured in pure form. Additionally, some colonies were cultured on potato dextrose agar slant medium at 30 °C for 1 week. DNA was extracted from the fungal isolates and amplified by PCR using primers 18SF1 (5´-AGGTTTCCGTAGGGTGAACCT-3´) and 58SR1 (5´-TTCGCTGCGTTCTTCATCGA-3´). Specific primers BjF3 (5´-ACCTTGCGCTCCTTGGTAT-3´) for B. adusta , a basidiomycete, and BjR3 (5´-CTCCACAGCAACGCAGAT-3´) were designed. Using the Polymerase-Chain-Reaction (PCR) products, other fungal species were identified using the Basic Local Alignment Search Tool (BLAST) database (https://macrogen-japan.co.jp/service/sequencing/). Evaluation of Cough and Sputum Symptoms The visual analog scale (VAS) for cough severity is a 100 mm straight line scale that patients use to assess the severity of their cough, from “no cough symptoms” (0 mm) to “the worst cough imaginable” (100 mm). 27 The chronic obstructive pulmonary disease (COPD) Assessment Test (CAT) is a validated self-report measure for assessing COPD symptoms. It is comprised of eight questions related to cough and sputum symptoms. Specifically, we used the scores from questions 1 (cough symptoms) and 2 (sputum symptoms). The scoring system ranged from 0 to 5, with higher scores indicating more severe symptoms. 28 Measurement of average monthly humidity in Nagasaki City The monthly average humidity for Nagasaki City was obtained from data observed by the Japan Weather Association using a hygrometer (https://www.jma.go.jp/jma/index.html). Statistical Analyses Statistical analyses were performed using the JMP® Pro software version 16.0.0 (SAS Institute, Cary NC). Continuous variables were presented as mean (standard deviation; SD). Differences between groups were assessed using the Wilcoxon’s rank sum test or Fisher’s exact probability test. Additionally, we investigated the correlation between the monthly mean humidity in Nagasaki and the detection rate of basidiomycetes in sputum using linear regression analysis. Statistical significance was set at a P < 0.05. Declarations Funding The authors received no funding for this work Acknowledgments The authors acknowledge the technical assistance provided by Aihara H and Mori M. Data availability The datasets analyzed during the current study available from the corresponding author on reasonable request. Declaration of Competing Interest There are no conflicts of interest to declare. Author Contributions Statement JI, SF, CFand YO conceived and designed the study. JI, SF, CF, and YO contributed to sample collection and interpretation. TT, ST, NS,and TN assisted in data analysis and interpretation of results. HM provided critical revision of the manuscript. JI drafted the manuscript. All authors reviewed, edited, and approved the final manuscript. Ethics approval and consent to participate This study was conducted in compliance with all applicable laws and regulations concerning the protection of participants’ privacy. Ethical approval was obtained from the Nagasaki University Hospital Clinical Research Ethics Committee in accordance with the “Ethical Guidelines for Life Sciences and Medical Research Involving Human Subjects” (Approval No.: 23091101-3). Written informed consent was obtained from all participants prior to study enrollment. References Mukae, H. et al. The Japanese respiratory society guidelines for the management of cough and sputum (digest edition). Respir Investig 59 , 270-290, doi:10.1016/j.resinv.2021.01.007 (2021). Irwin, R. 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Respir Investig 50 , 34-39, doi:10.1016/j.resinv.2012.05.003 (2012). Tables Table 1. Clinical characteristics of the CC and NC groups CC group, n=30 NC group, n=30 P value Age, mean 68.0 66.2 0.5587 Female, n (%) 23 (76.7) 16 (53.3) 0.1033 Smoking status Never smoker, n (%) 19 (63.3) 10 (33.3) 0.0201 Current or former smoker, n (%) 11 (36.7) 20 (66.7) Medications Inhaled corticosteroids, n (%) 22 (73.3) 0 (0) <0.0001 Antibacterial drug, n (%) 14 (46.7) 1 (0.3) 0.0004 Antifungal agent, n (%) 2 (6.67) 0 (0) 0.4915 Detection of Basidiomycete, n (%) 9 (30.0) 0 (0.0) 0.0019 CC, chronic cough; NC, non chronic cough. Table 2. Identified basidiomycetes Basidiomycete species N Irpex 5 Phanerochaete 3 Phanerodontia 2 Trametes 2 Bjerkandera 1 Ceriporia 1 Perenniporia 1 Rigidoporus 1 Crepatura 1 Phlebia 1 Table 3. Background comparison of patients with chronic cough between those with and without detected basidiomycetes Variables With Basidiomycete (n = 9) Without Basidiomycete (n = 21) P values Age, years, mean 69.7 64.8 0.2295 Female, n (%) 7 (77.78) 16 (76.2) 1.0000 Smoking status Never smoker, n (%) 7 (77.8) 12 (57.1) 0.4189 Current or former smoker, n (%) 2 (22.2) 0 (0) Medications Antibacterial drug, n (%) 3 (33.3) 10 (47.6) 0.6908 Antifungal agent, n (%) 0 (0) 2 (9.5) 1.0000 Proton pump inhibitor, n (%) 4 (44.4) 8 (38.1) 1.0000 Inhaled corticosteroid, n (%) 6 (66.7) 16 (76.2) 0.6662 VAS, mean 45.0 51.1 (31.6) 0.6446 COPD assessment test Q1 (frequency of coughing), mean 2.6 2.6 0.6240 Q2 (Frequency of sputum), mean 3.0 3.1 0.3609 Q1+Q2, mean 5.6 4.9 0.9441 Underlying disease UCC, n (%) 1 (11.1) 1 (4.8) 0.5172 RCC, n (%) 8 (88.9) 20 (95.2) Bronchial asthma, n (%) 5 (55.6) 17 (81.0) 0.1954 COPD, n (%) 1 (11.1) 2 (9.5) 1.0000 Chronic rhinosinusitis, n (%) 3 (33.3) 5 (23.8) 0.6662 Gastroesophageal reflux, n (%) 0 (0) 2 (9.5) 1.0000 Sample collection timing June-August, n (%) 6 (66.7) 5 (23.8) 0.0419 September-May, n (%) 3 (33.3) 16 (76.2) HRCT findings Cavity, yes, n (%) 2 (22.2) 2 (9.5) 0.5632 Bronchiectasis, yes, n (%) 2 (22.2) 5 (23.8) 1.0000 Mucoid impaction, yes, n (%) 2 (22.2) 5 (23.8) 1.0000 VAS, the visual analog scale; COPD, chronic obstructive pulmonary disease; UCC, Unexplained chronic cough; RCC, Refractory chronic cough; HRCT, high-resolution computed tomography. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7568485","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":618392604,"identity":"6fe80c3d-992c-437c-8665-3819b9ef99d1","order_by":0,"name":"Jun Iriki","email":"","orcid":"","institution":"Nagasaki University Graduate School of Biomedical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Jun","middleName":"","lastName":"Iriki","suffix":""},{"id":618392605,"identity":"4a097129-afbc-4057-8355-24f0d5b2cdcf","order_by":1,"name":"Takahiro Takazono","email":"","orcid":"","institution":"Nagasaki University 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Sciences","correspondingAuthor":false,"prefix":"","firstName":"Noriho","middleName":"","lastName":"Sakamoto","suffix":""},{"id":618392612,"identity":"a24c1288-56e5-4cfe-b5d6-ca50f7bd46b2","order_by":7,"name":"Chizu Fukushima","email":"","orcid":"","institution":"Nagasaki University Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chizu","middleName":"","lastName":"Fukushima","suffix":""},{"id":618392614,"identity":"0b10900f-ba1e-45fc-a7ae-5a5468b708b4","order_by":8,"name":"Tomoya Nishino","email":"","orcid":"","institution":"Nagasaki University Graduate School of Biomedical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Tomoya","middleName":"","lastName":"Nishino","suffix":""},{"id":618392617,"identity":"ee48a35f-c25b-41d8-8128-67f42381fb84","order_by":9,"name":"Hiroshi Mukae","email":"","orcid":"","institution":"Nagasaki University Graduate School of Biomedical Sciences","correspondingAuthor":false,"prefix":"","firstName":"Hiroshi","middleName":"","lastName":"Mukae","suffix":""}],"badges":[],"createdAt":"2025-09-09 02:38:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7568485/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7568485/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106381533,"identity":"0359d955-e152-42da-b414-45c795991ef8","added_by":"auto","created_at":"2026-04-08 05:22:48","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":36149,"visible":true,"origin":"","legend":"\u003cp\u003eBasidiomycetes were not detected in sputum collected during the winter months from November to February.\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7568485/v1/0fc38d40d6b55de328ace5a1.jpg"},{"id":106404455,"identity":"0caaa71c-86e4-44ff-b46c-80e0559d9131","added_by":"auto","created_at":"2026-04-08 09:16:02","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":71686,"visible":true,"origin":"","legend":"\u003cp\u003eThe monthly humidity average in Nagasaki correlated with the monthly detection rate of basidiomycetes in CC group (P = 0.0039, R\u003csup\u003e2\u003c/sup\u003e = 0.58).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7568485/v1/6e4efc881adbd41aaf1c9ff3.png"},{"id":108608908,"identity":"c24177bf-1f5c-4b93-b483-7ba97b613bd1","added_by":"auto","created_at":"2026-05-06 12:42:48","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":450081,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7568485/v1/d07ef43a-a94a-4dd2-aa2c-98b8cfa2341a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"A pilot study for Basidiomycete-associated chronic cough: A potential contributor to refractory and unexplained or refractory chronic cough","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCoughing is a biological defense response to expel foreign substances and secretions from the airways. Chronic cough is defined as a cough that persists for 8 weeks or longer.\u0026nbsp;\u003csup\u003e1\u003c/sup\u003e \u003csup\u003e2\u003c/sup\u003e In Japan, asthma-related cough is the most common cause of chronic cough; other common causes include atopic cough, gastroesophageal reflux disease, sino-bronchial syndrome, and post-infectious cough. \u003csup\u003e3\u003c/sup\u003e \u003csup\u003e4\u003c/sup\u003e \u003csup\u003e5\u003c/sup\u003e Unexplained chronic cough \u0026nbsp;(UCC) or refractory chronic cough (RCC) may also occur even with appropriate treatment of the underlying disease. Although several drug therapies, such as pregabalin\u0026nbsp;\u003csup\u003e6\u003c/sup\u003e and P2X3 receptor antagonists,\u0026nbsp;\u003csup\u003e7\u003c/sup\u003e have shown efficacy, an appropriate treatment algorithm for UCC/RCC has not been sufficiently validated.\u003c/p\u003e\n\u003cp\u003eIn 2009, Ogawa et al. reported a new disease called “fungus-associated chronic cough” (FACC). \u003csup\u003e8\u003c/sup\u003e FACC is defined as chronic cough in patients from whom environmental fungi are cultured in sputum and treated with a low dose of itraconazole. Basidiomycetes such as \u003cem\u003eBjerkandera adusta\u003c/em\u003e are considered the most important environmental fungi in the FACC. Despite conventional cough treatments, FACC does not improve, and patients with UCC/RCC may include those with FACC.\u0026nbsp;\u003csup\u003e9\u003c/sup\u003e However, these studies were limited to a single institution. The accurate detection of basidiomycetes in clinical specimens is challenging and there is no consensus on the laboratory method for their detection in airway samples. Consequently, the exact prevalence remains unknown.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn addition, basidiomycetes are detected year-round in outdoor or indoor environments but are more frequently detected in summer. \u003csup\u003e10\u003c/sup\u003e \u003csup\u003e11\u003c/sup\u003e \u003csup\u003e12\u003c/sup\u003e It has also been reported that the abundance of basidiomycetes is affected not only by temperature but also by humidity,\u0026nbsp;\u003csup\u003e13\u003c/sup\u003e \u003csup\u003e14\u003c/sup\u003e and there is a possibility that the onset of FACC is also seasonal. Ogawa et al. subsequently reported additional cases suggestive of FACC; \u003csup\u003e15\u003c/sup\u003e \u003csup\u003e16\u003c/sup\u003e however, the number of such cases was insufficient, and the sensitivity and specificity of the isolation and culture methods for basidiomycetes remain unknown. Therefore, it cannot be definitively stated that basidiomycetes in the airways cause chronic coughing or its subsequent pathogenesis. \u003c/p\u003e\n\u003cp\u003eIn the present pilot study, we aimed to investigate the reproducibility of findings related to FACC in a region different from that previously reported. Specifically, we performed fungal cultures of sputum from patients with UCC/RCC to determine whether basidiomycetes could be isolated in Nagasaki. Additionally, we compared the background factors of patients with chronic cough in whom basidiomycetes were detected.\u0026nbsp;\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cem\u003eParticipant Characteristics\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eSixty patients participated in the study and were divided into two groups: the CC group (n = 30) and the NC group (n = 30). Sputum samples were collected through self-expectoration from all participants. Table 1 summarizes the clinical characteristics of the study participants. Age did not differ significantly between the two groups (68.0 (10.2) years vs. 66.2 (12.9) years). In the CC group, there were seven males and 23 females, while the NC group had 14 males and 16 females (P = 1.000). Smoking history was present in 11 patients in the CC group and 20 in the NC group (P = 0.201).\u003c/p\u003e\n\u003cp\u003eIn the CC group, underlying diseases included bronchial asthma (22 patients), COPD (3), sinusitis (including sinus bronchial syndrome; 8), gastroesophageal reflux disease (2), and a history of thyroid tumor surgery (3). Two patients had UCC, and 28 patients had RCC that did not respond to treatment.\u003c/p\u003e\n\u003cp\u003eIn the NC group, 29 patients had lung tumors (16 adenocarcinomas, 6 small-cell carcinomas, 2 thymomas, 1 malignant scleral mesothelioma, 1 pulmonary artery vascular sarcoma, and 3 unknown histology). Among them, six had interstitial lung disease and five had COPD. One case of radiation pneumonitis was observed; however, there were no cases of bronchial asthma.\u003c/p\u003e\n\u003cp\u003eIn the CC group, 22 patients received regular inhaled steroids, 11 received macrolide antibacterial agents, and 2 received amphotericin B oral solution. In the NC group, one patient received tetracyclines.\u003c/p\u003e\n\u003cp\u003eFungal culture results showed that basidiomycetes were detected in 9 of CC group, whereas none were detected in NC group (P = 0.0019).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eIdentification of Basidiomycetes in Sputum Cultures\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGenetic analysis showed that the genera such as \u003cem\u003eIrpex\u0026nbsp;\u003c/em\u003e(\u003cem\u003eIrpex laceratus\u003c/em\u003e and\u003cem\u003e\u0026nbsp;Emmia lacerata\u003c/em\u003e) were detected in five cases; \u003cem\u003ePhanerochaete\u0026nbsp;\u003c/em\u003ein three; \u003cem\u003ePhanerodontia\u003c/em\u003e and \u003cem\u003eTrametes\u0026nbsp;\u003c/em\u003ein two; \u003cem\u003eBjerkandera\u003c/em\u003e, \u003cem\u003eCeriporia\u003c/em\u003e, \u003cem\u003eCrepatura\u003c/em\u003e, \u003cem\u003ePerenniporia\u003c/em\u003e, \u003cem\u003ePhlebia\u003c/em\u003e, and\u003cem\u003e\u0026nbsp;Rigidoporus\u0026nbsp;\u003c/em\u003ein one (Table 2). In addition to basidiomycetes, \u003cem\u003ePenicillium\u003c/em\u003e were detected in four cases, each of \u003cem\u003ePhomopsis\u003c/em\u003e and \u003cem\u003eCrepatura ellipsospora\u003c/em\u003e were detected in one case (Supplement).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eMonthly Number of Sputum Collection and Basidiomycetes Positivity and Monthly Humidity Average in Nagasaki City\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eFigure 1 illustrates the monthly number of sputum collections, Basidiomycetes positivity, and average monthly humidity\u0026nbsp;and temperature\u0026nbsp;in Nagasaki. Basidiomycetes were not detected in sputum collected during the winter months from November to February. The monthly humidity average in Nagasaki correlated with the monthly detection rate of basidiomycetes in CC group (P = 0.0039, R\u003csup\u003e2\u003c/sup\u003e = 0.58; Fig. 2A). Similarly, the average monthly temperature was also correlated with the monthly detection rate of basidiomycetes in the CC group (P = 0.0073, R2 = 0.53; Fig. 2B).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eBackground Comparison of Patients with Chronic Cough: Sputum Basidiomycetes Detected vs. Not Detected\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTable 3 compares the background characteristics of patients with chronic cough with and without basidiomycetes detected in sputum. Among patients with chronic cough, there were no significant differences in age, sex, smoking history, use of antibacterial and antifungal agents, inhaled steroids, proton pump inhibitor or comorbidities (bronchial asthma, COPD, sinusitis, or reflux esophagitis) between the patients detected and not detected basidiomycetes. No significant differences were seen in VAS and CAT scores. High-resolution computed tomography (HRCT) of the lungs at the time of sputum collection revealed cavitary lesions, bronchiectasis, and mucus plugs in some cases; however, no significant differences were seen between the two groups. About the timing of specimen collection, basidiomycetes were significantly more frequently detected in specimens collected between June and August (P = 0.0419). Of the nine cases basidiomycetes were detected in, two or more species were detected in four cases, but the background factors mentioned above did not differ from the other five cases (data not shown).\u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003e The primary results of this study were as follows: basidiomycetes were detected in the sputum of 9 of 30 patients with chronic cough, while no basidiomycetes were found in 30 patients with non-chronic cough (P = 0.0019). Additionally, basidiomycetes were detected only in sputum samples collected between June and August (P = 0.0419).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOur study, conducted in a different region than previously reported, found no basidiomycetes in patients with non-chronic cough. Thirty percent of the patients with chronic cough had basidiomycetes in their sputum. Previous reports have implicated basidiomycetes, including \u003cem\u003eB. adusta\u003c/em\u003e, in airway colonization in patients with airway lesions, such as bronchial asthma, COPD, chronic sinusitis, and interstitial pneumonia. \u003csup\u003e17\u003c/sup\u003e \u003csup\u003e18\u003c/sup\u003e \u003csup\u003e19\u003c/sup\u003e \u003csup\u003e20\u003c/sup\u003e In our study, basidiomycetes were detected in five patients with bronchial asthma, three with chronic sinusitis, and one with COPD, suggesting that some patients with chronic cough may have basidiomycete colonization and be diagnosed with RCC. Although there were no significant differences in use of inhaled steroids between the patients detected and not detected basidiomycetes, it is necessary to increase the sample size and continue the study. A previous report found \u003cem\u003eB. adusta\u003c/em\u003e in 14 of 31 patients with fungal allergic bronchopulmonary aspergillosis (FACC), and other basidiomycetes in 17 patients. \u003csup\u003e21\u003c/sup\u003e However, reports on the types and frequencies of other basidiomycete species are scarce. In our study, we detected 10 genera of the phylum Basidiomycota, with\u003cem\u003e\u0026nbsp;Irpex\u003c/em\u003e being the most frequently isolated and \u003cem\u003eBjerkandera\u003c/em\u003e detected in only one case. Although \u003cem\u003eBjerkandera\u003c/em\u003e is reported to be more frequently detected outdoors compared with \u003cem\u003eCladosporium\u003c/em\u003e, \u003cem\u003ePenicillium\u003c/em\u003e, \u003cem\u003eAlternaria\u003c/em\u003e, and \u003cem\u003eAspergillus\u003c/em\u003e,\u0026nbsp;\u003csup\u003e22\u003c/sup\u003e the species isolated from different regions may vary.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eBasidiomycetes, such as \u003cem\u003eB. adusta\u003c/em\u003e, have been implicated as causative antigens in allergic bronchopulmonary mycosis. \u003csup\u003e23\u003c/sup\u003e Fifteen percent of patients with chronic cough with detected basidiomycetes had mucus plugs in the bronchioles based on HRCT findings. \u003csup\u003e24\u003c/sup\u003e In our study, mucous plugs were found in the peripheral airways of two of nine patients (22.2%) with detected basidiomycetes. Previous reports suggested allergic cough due to basidiomycetes sensitization based on increased eosinophils in sputum of patients with FACC and the results of bronchial provocation and lymphocyte stimulation tests using\u0026nbsp;\u003cem\u003eB. adusta\u003c/em\u003e antigen solution.\u0026nbsp;\u003csup\u003e25\u003c/sup\u003e However, in our study, we used self-expectorated sputum rather than induced sputum for culture testing, and we did not use the Miller \u0026amp; Jones or Geckler classifications, so the quality of the sputum samples varied, and the basidiomycetes detected may have been established in the upper respiratory tract, including the pharyngeal mucosa. Our study did not evaluate eosinophils in sputum, and no report has definitively verified this association. Further interventional studies are needed to elucidate the pathogenesis of chronic cough in patients with basidiomycosis, including antifungal agent administration and reexamination of sputum cultures after symptom improvement.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eB. adusta\u003c/em\u003e is widely distributed indoors and outdoors globally but is mainly detected in summer.\u0026nbsp;\u003csup\u003e10\u003c/sup\u003e In the present study, no basidiomycetes were detected in samples collected during winter. Additionally, humidity correlated with the detection rate of basidiomycetes. Our results may suggest that basidiomycetes cause chronic coughing, especially during summer. In our study, no antifungal drugs were administered to patients with basidiomycosis, and there was no seasonal variation in cough symptoms in cases where basidiomycosis was detected. As there have been no previous reports of seasonal variation in cough symptoms in patients diagnosed with FACC, it is necessary to conduct follow-up surveys of patients where basidiomycosis was detected. Since basidiomycetes are rarely detected in microbiological sputum examinations in general medical facilities, cases of FACC may be overlooked. In patients with chronic cough unresponsive to appropriate treatment, sputum culture using fungal medium should be considered with FACC in mind. The limitations of this pilot study included the small sample size, timing of specimen collection, and bias in comorbidities. Additionally, a causal relationship between basidiomycetes isolation and symptoms has not been proven. Large-scale observational studies and interventional trials are needed to evaluate symptom improvement following antifungal treatment.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn Nagasaki, a region distinct from those previously reported, basidiomycetes were detected in the sputum of 30% of patients with chronic cough, while they were entirely absent in patients without chronic cough. The correlation between season and humidity with the frequency of basidiomycete identification indirectly underscores the clinical significance of fungal airway colonization and contamination.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cem\u003eStudy Design\u0026nbsp;\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Between June 1, 2022, and March 31, 2024, patients with UCC/RCC who live in Nagasaki City and visited our respiratory medicine outpatient clinic or were admitted to the respiratory medicine department at our institution were included in the chronic cough group (CC group). Spontaneous sputum samples were collected from these patients after obtaining their consent. Additionally, patients admitted to our department for the examination or treatment of respiratory diseases (such as lung cancer or interstitial pneumonia) were included in the non-chronic cough group (NC group). These patients had no cough symptoms or obvious airway infections and were able to provide sputum samples. Patients with a performance status of 3 or higher, poor general condition, or difficulty in self-expectorating were excluded from the study. The collected sputum samples were subjected to fungal cultures on the same day. This single-center, prospective, observational study was conducted in accordance with the ethical standards outlined in the Declaration of Helsinki. The study protocol was approved by the Ethics Committee of our institution (Approval No. 23091101).\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eDiagnosis of Chronic Cough\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; According to the 2019 guidelines of the Japanese Respiratory Society for the treatment of cough and sputum, patients with persistent cough symptoms lasting for more than 8 weeks are diagnosed with chronic cough. \u003csup\u003e1\u003c/sup\u003e UCC refers to chronic coughing of unknown origin that persists despite adequate treatment, including empiric therapy. chronic cough that does not improve even with appropriate treatment for conditions such as cough asthma and gastroesophageal reflux disease is referred to as RCC. \u003csup\u003e26\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eMycological Study\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003eSputum samples collected from the patients were applied to Sabouraud dextrose agar (210950, Becton, Dickinson and Company, BD, Tokyo, Japan) and incubated at 30 °C for 2 weeks. Emergent basidiomycete colonies were isolated on potato dextrose agar (213400, BD Biosciences) and cultured in pure form. Additionally, some colonies were cultured on potato dextrose agar slant medium at 30 °C for 1 week. DNA was extracted from the fungal isolates and amplified by PCR using primers 18SF1 (5´-AGGTTTCCGTAGGGTGAACCT-3´) and 58SR1 (5´-TTCGCTGCGTTCTTCATCGA-3´). Specific primers BjF3 (5´-ACCTTGCGCTCCTTGGTAT-3´) for \u003cem\u003eB.\u003c/em\u003e\u003cem\u003e\u0026nbsp;adusta\u003c/em\u003e, a basidiomycete, and BjR3 (5´-CTCCACAGCAACGCAGAT-3´) were designed. Using the Polymerase-Chain-Reaction (PCR) products, other fungal species were identified using the Basic Local Alignment Search Tool (BLAST) database (https://macrogen-japan.co.jp/service/sequencing/).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eEvaluation of Cough and Sputum Symptoms\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe visual analog scale (VAS) for cough severity is a 100 mm straight line scale that patients use to assess the severity of their cough, from “no cough symptoms” (0 mm) to “the worst cough imaginable” (100 mm).\u0026nbsp;\u003csup\u003e27\u003c/sup\u003e The chronic obstructive pulmonary disease (COPD) Assessment Test (CAT) is a validated self-report measure for assessing COPD symptoms. It is comprised of eight questions related to cough and sputum symptoms. Specifically, we used the scores from questions 1 (cough symptoms) and 2 (sputum symptoms). The scoring system ranged from 0 to 5, with higher scores indicating more severe symptoms.\u0026nbsp;\u003csup\u003e28\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eMeasurement of average monthly humidity in Nagasaki City\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe monthly average humidity for Nagasaki City was obtained from data observed by the Japan Weather Association using a hygrometer (https://www.jma.go.jp/jma/index.html).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003cem\u003eStatistical Analyses\u003c/em\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStatistical analyses were performed using the JMP® Pro software version 16.0.0\u0026nbsp;(SAS Institute, Cary NC). Continuous variables were presented as mean (standard\u0026nbsp;deviation; SD). Differences between groups were assessed using\u0026nbsp;the Wilcoxon’s rank sum test or Fisher’s exact probability test. Additionally, we investigated the correlation between the monthly mean humidity\u0026nbsp;in Nagasaki and the detection rate of basidiomycetes in sputum using linear regression analysis. Statistical significance was set at a P \u0026lt; 0.05.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors received no funding for this work\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors acknowledge the technical assistance\u0026nbsp;provided by Aihara H and Mori M.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets analyzed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere are no conflicts of interest to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eJI, SF, CFand YO conceived and designed the study. JI, SF, CF, and YO contributed to sample collection and interpretation. TT, ST, NS,and TN assisted in data analysis and interpretation of results. HM provided critical revision of the manuscript. JI drafted the manuscript. All authors reviewed, edited, and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in compliance with all applicable laws and regulations concerning the protection of participants’ privacy. Ethical approval was obtained from the Nagasaki University Hospital Clinical Research Ethics Committee in accordance with the “Ethical Guidelines for Life Sciences and Medical Research Involving Human Subjects” (Approval No.: 23091101-3). Written informed consent was obtained from all participants prior to study enrollment.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eMukae, H.\u003cem\u003e et al.\u003c/em\u003e The Japanese respiratory society guidelines for the management of cough and sputum (digest edition). \u003cem\u003eRespir Investig\u003c/em\u003e \u003cstrong\u003e59\u003c/strong\u003e, 270-290, doi:10.1016/j.resinv.2021.01.007 (2021).\u003c/li\u003e\n\u003cli\u003eIrwin, R. S., French, C. L., Chang, A. B. \u0026amp; Altman, K. W. Classification of Cough as a Symptom in Adults and Management Algorithms: CHEST Guideline and Expert Panel Report. \u003cem\u003eChest\u003c/em\u003e \u003cstrong\u003e153\u003c/strong\u003e, 196-209, doi:10.1016/j.chest.2017.10.016 (2018).\u003c/li\u003e\n\u003cli\u003eMatsumoto, H.\u003cem\u003e et al.\u003c/em\u003e Prevalence and clinical manifestations of gastro-oesophageal reflux-associated chronic cough in the Japanese population. \u003cem\u003eCough\u003c/em\u003e \u003cstrong\u003e3\u003c/strong\u003e, 1, doi:10.1186/1745-9974-3-1 (2007).\u003c/li\u003e\n\u003cli\u003eYamasaki, A.\u003cem\u003e et al.\u003c/em\u003e Cough and asthma diagnosis: physicians\u0026apos; diagnosis and treatment of patients complaining of acute, subacute and chronic cough in rural areas of Japan. \u003cem\u003eInt J Gen Med\u003c/em\u003e \u003cstrong\u003e3\u003c/strong\u003e, 101-107, doi:10.2147/ijgm.s8167 (2010).\u003c/li\u003e\n\u003cli\u003eNiimi, A.\u003cem\u003e et al.\u003c/em\u003e Cough variant and cough-predominant asthma are major causes of persistent cough: a multicenter study in Japan. \u003cem\u003eJ Asthma\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 932-937, doi:10.3109/02770903.2013.823444 (2013).\u003c/li\u003e\n\u003cli\u003eVertigan, A. 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T.\u003cem\u003e et al.\u003c/em\u003e Fungal Spore Richness in School Classrooms is Related to Surrounding Forest in a Season-Dependent Manner. \u003cem\u003eMicrob Ecol\u003c/em\u003e \u003cstrong\u003e84\u003c/strong\u003e, 351-362, doi:10.1007/s00248-021-01844-2 (2022).\u003c/li\u003e\n\u003cli\u003eAl-Shaarani, A.\u003cem\u003e et al.\u003c/em\u003e Analysis of Airborne Fungal Communities on Pedestrian Bridges in Urban Environments. \u003cem\u003eMicroorganisms\u003c/em\u003e \u003cstrong\u003e11\u003c/strong\u003e, doi:10.3390/microorganisms11082097 (2023).\u003c/li\u003e\n\u003cli\u003eCouceiro, D. \u0026amp; Couceiro, S. Wood-inhabiting macrofungi Hymenochaetales and Polyporales (Basidiomycota) in the Amazon Forest: relationship the abiotic factors and substrate colonization. \u003cem\u003eAnais da Academia Brasileira de Ci\u0026ecirc;ncias\u003c/em\u003e \u003cstrong\u003e94\u003c/strong\u003e, doi:10.1590/0001-3765202220210554 (2022).\u003c/li\u003e\n\u003cli\u003eOgawa, H., Fujimura, M., Ohkura, N. \u0026amp; Makimura, K. It is time to call attention to the clinical significance of fungal colonization in chronic cough. \u003cem\u003eAllergol Int\u003c/em\u003e \u003cstrong\u003e63\u003c/strong\u003e, 611-612, doi:10.2332/allergolint.14-LE-0691 (2014).\u003c/li\u003e\n\u003cli\u003eOgawa, H., Fujimura, M., Takeuchi, Y., Makimura, K. \u0026amp; Satoh, K. Sensitization to Bjerkandera adusta enhances severity of cough symptom in patients with fungus-associated chronic cough (FACC). \u003cem\u003eMed Mycol J\u003c/em\u003e \u003cstrong\u003e52\u003c/strong\u003e, 205-212, doi:10.3314/mmj.52.205 (2011).\u003c/li\u003e\n\u003cli\u003eKatayama, N., Fujimura, M., Yasui, M., Ogawa, H. \u0026amp; Nakao, S. Hypersensitivity pneumonitis and bronchial asthma attacks caused by environmental fungi. \u003cem\u003eAllergol Int\u003c/em\u003e \u003cstrong\u003e57\u003c/strong\u003e, 277-280, doi:10.2332/allergolint.C-07-56 (2008).\u003c/li\u003e\n\u003cli\u003eChowdhary, A.\u003cem\u003e et al.\u003c/em\u003e Clinical significance of filamentous basidiomycetes illustrated by isolates of the novel opportunist Ceriporia lacerata from the human respiratory tract. \u003cem\u003eJ Clin Microbiol\u003c/em\u003e \u003cstrong\u003e51\u003c/strong\u003e, 585-590, doi:10.1128/jcm.02943-12 (2013).\u003c/li\u003e\n\u003cli\u003eVerma, S.\u003cem\u003e et al.\u003c/em\u003e Schizophillum commune causing sinusitis with nasal polyposis in the sub-Himalayan region: first case report and review. \u003cem\u003eMycopathologia\u003c/em\u003e \u003cstrong\u003e177\u003c/strong\u003e, 103-110, doi:10.1007/s11046-013-9717-1 (2014).\u003c/li\u003e\n\u003cli\u003eIizasa, T.\u003cem\u003e et al.\u003c/em\u003e Colonization with Schizophyllum commune of Localized Honeycomb Lung with Mucus. \u003cem\u003eRespiration\u003c/em\u003e \u003cstrong\u003e68\u003c/strong\u003e, 201-203, doi:10.1159/000050493 (2001).\u003c/li\u003e\n\u003cli\u003eOgawa, H., Fujimura, M., Ohkura, N., Satoh, K. \u0026amp; Makimura, K. Impact of Bjerkandera adusta Colonization on Chronic Cough. \u003cem\u003eAllergology international : official journal of the Japanese Society of Allergology\u003c/em\u003e \u003cstrong\u003e63\u003c/strong\u003e, doi:10.2332/allergolint.13-LE-0665 (2014).\u003c/li\u003e\n\u003cli\u003eSautour, M.\u003cem\u003e et al.\u003c/em\u003e Profiles and seasonal distribution of airborne fungi in indoor and outdoor environments at a French hospital. \u003cem\u003eSci Total Environ\u003c/em\u003e \u003cstrong\u003e407\u003c/strong\u003e, 3766-3771, doi:10.1016/j.scitotenv.2009.02.024 (2009).\u003c/li\u003e\n\u003cli\u003eChowdhary, A., Agarwal, K. \u0026amp; Meis, J. F. Filamentous Fungi in Respiratory Infections. What Lies Beyond Aspergillosis and Mucormycosis? \u003cem\u003ePLoS Pathog\u003c/em\u003e \u003cstrong\u003e12\u003c/strong\u003e, e1005491, doi:10.1371/journal.ppat.1005491 (2016).\u003c/li\u003e\n\u003cli\u003eOkumura, K.\u003cem\u003e et al.\u003c/em\u003e Mucus plugs and bronchial wall thickening on three-dimensional computed tomography in patients with unexplained chronic cough whose sputum yielded filamentous Basidiomycetes. \u003cem\u003eEur Radiol\u003c/em\u003e \u003cstrong\u003e30\u003c/strong\u003e, 3268-3276, doi:10.1007/s00330-020-06664-5 (2020).\u003c/li\u003e\n\u003cli\u003eOgawa, H., Fujimura, M., Takeuchi, Y. \u0026amp; Makimura, K. Is Bjerkandera adusta Important to fungus-associated chronic cough as an allergen? Eight cases\u0026apos; reports. \u003cem\u003eJ Asthma\u003c/em\u003e \u003cstrong\u003e46\u003c/strong\u003e, 849-855, doi:10.3109/02770900903199946 (2009).\u003c/li\u003e\n\u003cli\u003eGibson, P.\u003cem\u003e et al.\u003c/em\u003e Treatment of Unexplained Chronic Cough: CHEST Guideline and Expert Panel Report. \u003cem\u003eChest\u003c/em\u003e \u003cstrong\u003e149\u003c/strong\u003e, 27-44, doi:10.1378/chest.15-1496 (2016).\u003c/li\u003e\n\u003cli\u003eMartin Nguyen, A.\u003cem\u003e et al.\u003c/em\u003e Validation of a visual analog scale for assessing cough severity in patients with chronic cough. \u003cem\u003eTher Adv Respir Dis\u003c/em\u003e \u003cstrong\u003e15\u003c/strong\u003e, 17534666211049743, doi:10.1177/17534666211049743 (2021).\u003c/li\u003e\n\u003cli\u003eTsuda, T.\u003cem\u003e et al.\u003c/em\u003e Development of the Japanese version of the COPD Assessment Test. \u003cem\u003eRespir Investig\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 34-39, doi:10.1016/j.resinv.2012.05.003 (2012).\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003cstrong\u003eTable 1.\u0026nbsp;\u003c/strong\u003eClinical characteristics of the CC and NC groups\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"632\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 255px;\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003eCC group, n=30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003eNC group, n=30\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003eP value\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003eAge, mean\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e68.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e66.2\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.5587\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003eFemale, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e23 (76.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e16 (53.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.1033\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003eSmoking status\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003e\u0026nbsp;Never smoker, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e19 (63.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e10 (33.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.0201\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003e\u0026nbsp;Current or former smoker, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e11 (36.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e20 (66.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003eMedications\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003eInhaled corticosteroids, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e22 (73.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u0026lt;0.0001\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003eAntibacterial drug, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e14 (46.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e1 (0.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.0004\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003eAntifungal agent, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e2 (6.67)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e0.4915\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 255px;\"\u003e\n \u003cp\u003eDetection of\u0026nbsp;Basidiomycete, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e9 (30.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 142px;\"\u003e\n \u003cp\u003e0 (0.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 93px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0019\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCC, chronic cough; NC, non chronic cough.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u0026nbsp;\u003c/strong\u003eIdentified basidiomycetes\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003eBasidiomycete species\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003eIrpex\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003ePhanerochaete\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003ePhanerodontia\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003eTrametes\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003eBjerkandera\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003eCeriporia\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003ePerenniporia\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003eRigidoporus\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003eCrepatura\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 274px;\"\u003e\n \u003cp\u003e\u003cem\u003ePhlebia\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 94px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3.\u0026nbsp;\u003c/strong\u003eBackground comparison of patients with chronic cough between those with and without detected basidiomycetes\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"605\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVariables\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWith\u003c/strong\u003e \u003cstrong\u003eBasidiomycete\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;(n = 9)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWithout\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eBasidiomycete\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;(n = 21)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP values\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eAge, years, mean\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e69.7\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e64.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.2295\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eFemale, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e7 (77.78)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e16 (76.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eSmoking status\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e\u003cs\u003e\u0026nbsp;\u003c/s\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e\u003cs\u003e\u0026nbsp;\u003c/s\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eNever smoker, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e7 (77.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e12 (57.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" rowspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.4189\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eCurrent or former smoker, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2 (22.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eMedications\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eAntibacterial drug, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e3 (33.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e10 (47.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.6908\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eAntifungal agent, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2 (9.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eProton pump inhibitor, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e4 (44.4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e8 (38.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eInhaled corticosteroid, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e6\u0026nbsp;(66.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e16 (76.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.6662\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eVAS, mean\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e45.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e51.1 (31.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.6446\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eCOPD assessment test\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eQ1 (frequency of coughing), mean\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.6240\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eQ2 (Frequency of sputum), mean\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e3.0\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e3.1\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.3609\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eQ1+Q2, mean\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e5.6\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e4.9\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.9441\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eUnderlying disease\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eUCC, n (%)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e1 (11.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e1 (4.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" rowspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.5172\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eRCC, n (%)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e8 (88.9)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e20 (95.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eBronchial asthma, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e5 (55.6)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e17 (81.0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.1954\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eCOPD, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e1 (11.1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2 (9.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eChronic rhinosinusitis, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e3 (33.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e5 (23.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.6662\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eGastroesophageal reflux, n (%)\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e0 (0)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2 (9.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eSample collection timing\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" valign=\"top\" style=\"width: 85px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eJune-August, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 161px;\"\u003e\n \u003cp\u003e6 (66.7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e5 (23.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" rowspan=\"2\" style=\"width: 85px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.0419\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eSeptember-May, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 161px;\"\u003e\n \u003cp\u003e3 (33.3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e16 (76.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eHRCT\u0026nbsp;findings\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eCavity, yes, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2 (22.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2 (9.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e0.5632\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eBronchiectasis, yes, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2 (22.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e5 (23.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 198px;\"\u003e\n \u003cp\u003eMucoid impaction, yes, n (%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e2 (22.2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 161px;\"\u003e\n \u003cp\u003e5 (23.8)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 85px;\"\u003e\n \u003cp\u003e1.0000\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eVAS, the visual analog scale; COPD, chronic obstructive pulmonary disease; UCC, Unexplained chronic cough; RCC, Refractory chronic cough; HRCT, high-resolution computed tomography.\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"fungus-associated chronic cough, chronic cough of unknown cause, treatment-resistant chronic cough, basidiomycete, fungi culture","lastPublishedDoi":"10.21203/rs.3.rs-7568485/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7568485/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Recent evidence suggests a potential association between chronic cough and environmental fungi, particularly basidiomycetes, giving rise to the concept of fungus-associated chronic cough (FACC). However, the role of basidiomycetes in chronic cough remains poorly understood. In this pilot study, we investigated 30 patients with unexplained or refractory chronic cough (UCC/RCC) and 30 patients with other respiratory diseases (non-chronic cough). Spontaneous sputum samples were collected for fungal culture, and participants completed a cough and sputum symptom questionnaire, underwent chest computed tomography, and were evaluated for underlying diseases and medication use. Analyses were conducted by chronic cough status and by basidiomycete detection. Basidiomycetes were detected in the sputum of 9 out of 30 chronic cough patients but in none of the non-chronic cough patients (P = 0.0019), with a significant seasonal peak from June to August (P = 0.0419). No associations were observed with age, sex, underlying diseases, cough severity, or high-resolution computed tomography findings. These results indicate that basidiomycete colonization may contribute to FACC in individuals with UCC/RCC, particularly during the summer months.","manuscriptTitle":"A pilot study for Basidiomycete-associated chronic cough: A potential contributor to refractory and unexplained or refractory chronic cough","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-08 05:22:45","doi":"10.21203/rs.3.rs-7568485/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2297588b-e969-495c-b433-ab686f1a5b57","owner":[],"postedDate":"April 8th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Withdrawn","date":"2026-05-06T12:30:48+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":65803225,"name":"Health sciences/Diseases"},{"id":65803226,"name":"Health sciences/Medical research"},{"id":65803227,"name":"Biological sciences/Microbiology"}],"tags":[],"updatedAt":"2026-05-06T12:42:39+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-08 05:22:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7568485","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7568485","identity":"rs-7568485","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}