Myocarditis Caused by Metapneumovirus with Klebsiella pneumoniae Infection: A Case Report

Myocarditis Caused by Metapneumovirus with Klebsiella pneumoniae Infection: A Case Report | 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 Case Report Myocarditis Caused by Metapneumovirus with Klebsiella pneumoniae Infection: A Case Report Shih-Hung Wang, Mei-Hui Lee, Yuarn-Jang Lee, Yung-Ching Liu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4478998/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 Background Human metapneumovirus (hMPV), classified in the Pneumoviridae family, primarily causes lower respiratory tract infections in children and immunocompromised individuals. However, rare cases have highlighted hMPV infections manifesting beyond the respiratory system, including cardiac impairment. Case presentation We report the case of a 68-year-old man who presented at the emergency room with dyspnea and fever and who rapidly progressed to septic shock with increasing oxygen requirements, necessitating transfer to the medical intensive care unit (MICU). Diagnostic evaluations comprising cardiac echocardiography and coronary angiography were utilized to confirmmyocarditis while ruling out acute myocardial infarction. Despite the implementation of extracorporeal membrane oxygenation (ECMO) and intra-aortic balloon pump (IABP)therapy, the patient succumbed to the illness three days after admission to the MICU. Polymerase chain reaction (PCR) of a throat swab confirmed the diagnosis of Metapneumovirus infection, and Klebsiella pneumoniae was concurrently detected through sputum culture. Conclusions Compared to previously reported cases of metapneumovirus-related myocarditis, this case is the first to demonstrate a notably adverse outcome associated with the concurrent presence of bacterial infection. Metapneumovirus Klebsiella pneumoniae Myocarditis Figures Figure 1 Figure 2 Background Human metapneumovirus (hMPV), an emerging respiratory virus first isolated in 2001 [ 1 ], has been reported worldwide. As a nonsegmented, negative-sense RNA virus [ 1 ], it primarily causes upper and lower respiratory tract infections in children [ 2 ] and threatens the health of elderly and immunocompromised individuals [ 3 ]. The clinical features of the illness caused by hMPV infection range from mild upper respiratory tract infection to life-threatening severe bronchiolitis and pneumonia. In Taiwan, 16.8% of children hospitalized with bronchiolitis are infected with hMPV [ 4 ]. However, rare cases have highlighted hMPV infections manifesting beyond the respiratory system, including cardiac impairment. Acute myocarditis secondary to hMPV infection has only been described twice in adult case reports; this condition has a good prognosis with no other infection combined [ 5 , 6 ]. Here, we present a case of severe pneumonia and myocarditis caused by hMPV infection in an elderly patient. To the best of our knowledge, this is the first case of severe myocarditis caused by metapneumovirus infection detected by the FilmArray® Pneumonia Multiplex PCR Panel with poor outcomes. Case presentation The patient was sent to our emergency room because of fever, a productive cough, and progressive dyspnea for one day. Upon arrival at our hospital, he presented with clear consciousness, tachycardia (143 beats/min), tachypnea (28 breaths/min), blood pressure within the normal range (106/88 mmHg), and fever (38.4°C). Neither chills, muscle soreness, nor limb weakness was noted. He had no recent travel, tick bites, or acute upper respiratory infections. The patient had underlying diabetes mellitus and hypertension and was receiving regular medical control. He also had liver cirrhosis with chronic hepatitis B infection and received 0.5 mg/d entecavir regularly. He had no history of head trauma or psychiatric or psychological disease. He had no tuberculosis or lung cancer. He was a smoker (quit for 10 years) with a drug addiction. She resides in Guangdong Province, southern China. She had no recent travel, tick bites, or acute upper respiratory infections. She had not been in direct contact with any birds, poultry or horses. She did not shop at live bird markets, nor did she have friends or relatives with pet birds. On physical examination, lung auscultation revealed crackles in the right lung fields. Laboratory tests revealed that the white blood cell (WBC) count was 3240/µL, with 49% neutrophils (10% of the band form) and 33% lymphocytes. Her lactate level was 12.2 mmol/L, and she exhibited metabolic acidosis and a high procalcitonin level (50.75 mg/dL). Her troponin-I concentration was 248 pg/mL, her CPK concentration was 662 U/L, and her CKMB concentration was 1.9 ng/mL. platelet was 221000/µL. BUN and creatinine were 39 mg/dL and 2/34 mg/dL, respectively. AST was 111 IU/L. Electrolytes were within the normal range. Urine analysis revealed amber-colored bacteria (296.6/µL) and no pyuria. Chest X-ray revealed alveolar infiltration in the right middle lobe (Fig. 1 ). An electrocardiogram (ECG) showed sinus tachycardia (Fig. 2 ). Piperacillin/tazobactam (4500 mg) was administered as empiric antibiotics. His clinical condition deteriorated rapidly to septic shock with severe hypoxemia and hypotension (78/49 mmHg) during the routine examination. Non-invasive cardiac output hemodynamic monitor showed low stroke volume and low systemic vascular resistance. Epinephrine 20 mL/hr. was administered via a central vein catheter. After tracheal intubation and ventilator-assisted ventilation, he was transferred to the MICU for further treatment (on day 0). In the MICU, arterial blood gas analysis initially revealed a pH of 7.322, PO2 of 315.3 mmHg, PCO2 of 23.3 mmHg, HCO3 of 11.8 mmol/L and FiO2 of 60%. Due to persistent hypotension (75/51 mmHg), an infusion of vasopressin and adrenaline was added. With progressive dyspnea, arterial blood gas analysis revealed a pH of 7.23, PO2 of 114.2 mmHg, PCO2 of 46.2 mmHg, HCO3 of 18.9 mmol/L and FiO2 of 100%. Chest X-ray revealed cardiomegaly and progressive infiltration in the bilateral lung, which indicated progressive pneumonia with ARDS. On the next day (day 1), the WBC count was 3070/µL. BUN and creatinine were 38 mg/dL and 1.78 mg/dL, respectively. Her AST level increased to 2035 IU/L, and her ALT level was 679 IU/L. Troponin-I (2167 pg/mL), CPK (3319 U/L), and CKMB (182 mg/dL) were elevated. The lactate concentration was 18.1 mmol/L (Table 1 ). ECG revealed diffuse S-T elevation. ECMO was performed at the right femoral artery and right femoral vein. Cardiac echocardiography revealed an left ventricular ejection fraction of 15% with global left ventricular hypokinesis and blood stasis within the LV, which indicated acute heart failure with reduced ejection fraction, suspected stress cardiomyopathy and myocarditis. A coronary angiography was performed to rule out acute myocardial infarction and showed no significant vessel obstruction. IABP was inserted into the descending aorta. However, the patient ultimately died 2 days after admission. Concerning the presence of the pathogen, the results of two sets of peripheral blood cultures and urine cultures during episodes of fever were negative. The film array multiplex panel showed negative findings for parainfluenza virus (types 1–4), adenovirus, rhinovirus, enterovirus, Mycoplasma pneumoniae , Bordetella parapertusis, and Bordetella pertussis ; however, hMPV was positive. Moreover, sputum culture revealed the pathogen Klebsiella pneumoniae with KeyMyth Klbsiella pneumoniae Serotype 1 (Key Myth Biotech, Co. Ltd. Taiwan). The final diagnoses were infection with Klebsiella pneumoniae and metapneumovirus, severe community-acquired pneumonia, type I respiratory failure, acute respiratory distress syndrome (ARDS), and myocarditis. Table 1 Initial laboratory findings Day 0 Day 2 WBC (count/uL) Neutrophil (band) Lymphocyte 3240 49% (10%) 33% 3070 - - Hb (g/dL) 15.3 12.7 Platelet (count/uL) 221000 19000 BUN (mg/dL) Creatinine (mg/dL) 9 2.34 38 1.78 Procalcitonin (ng/mL) 50.75 - BNP (pg/mL) 44.8 - Troponin-I (pg/mL) 248.7 33328.4 CKMB (ng/mL) 1.9 182 CPK (U/L) 662 3319 GOT (IU/L) 111 2035 Total bilirubin (mg/dL) 0.9 4.7 Direct bilirubin (mg/dL) - 0.7 Lactate (mmol/L) 12.2 18.1 Na (mmol/L) 136 145 K (mmol/L) 4.8 4.4 Cl (mmol/L)) 103 106 Discussion and conclusions hMPV infection in the myocardium Although hMPV infection mostly manifests via the upper and lower respiratory tract, several case reports of myocarditis caused by hMPV infection in children, elderly individuals and immunocompromised patients have been published. Compared to influenza and RSV infections, hMPV infection is more commonly associated with cardiovascular disease. Although hMPV has been identified as one of the etiologic agents of acute myocarditis, the detailed mechanism is still unclear, as is whether the virus has a tropism for the myocardium or whether patients with underlying cardiovascular disease are more vulnerable to hMPV. Acute myocarditis secondary to hMPV infection has only been described twice in adult patients who have a good prognosis with no other pathogen infection combined. In the present case, we revealed a poor prognosis in patients with hMPV myocarditis complicated with severe ARDS and concurrent infection with Klebsiella pneumoniae . Treatment with hMPV The treatment approach for hMPV primarily involves supportive care and may vary based on different clinical presentations. Certain drugs, such as ribavirin, have shown potential antiviral activity against hMPV in vitro [ 7 ] but still lack large-scale clinical efficacy data [28,29]. A meta-analysis provided some supportive evidence for IVIG therapy in acute myocarditis patients, but the role of anti-inflammatory therapy, IVIG, steroids, and antiviral therapy in hMPV myocarditis is still unclear [ 8 ]. There have been case reports and in vitro studies exploring antiviral therapies such as immunoglobulins or monoclonal antibodies [ 9 , 10 ]. However, the exact efficacy of these treatments still requires further evaluation. The rate of concurrent bacterial lung infections or bacteremia is greater in children infected with hMPV [ 11 ] than in those infected with RSV. In the case of hMPV, antibiotics tend to be administered because of concerns regarding concomitant bacterial pneumonia even if a bacterial pathogen is ultimately not isolated [ 12 ]. In prevention, in addition to enhancing personal hygiene and decreasing infection exposure, several vaccines are currently in development for preventing hMPV infection [ 13 ]. These vaccines primarily target the F protein of hMPV, inducing an immune response to enhance immunity against hMPV. Further research is needed to assess the safety and efficacy of these vaccines. In addition to live attenuated and subunit protein vaccines undergoing trial development, there is ongoing development of mRNA vaccines, which have completed phase 1 clinical trials, demonstrating safety and immunogenicity in healthy adults [ 14 ]. Limitations Initially, safety concerns precluded the acquisition of myocardial and pericardial biopsies, rendering the pathologic confirmation of myopericarditis diagnosis unattainable. Additionally, cardiac magnetic resonance (CMR) imaging was omitted in this instance. CMR imaging is recognized as a pivotal diagnostic tool for myocarditis that effectively distinguishes between ischemic and nonischaemic cardiomyopathy. In this case, coronary angiography revealed unremarkable coronary arteries without significant vessel obstruction, which decreased the possibility of myocardial infarction. Furthermore, the absence of bronchoscopy limited respiratory virus PCR to an upper respiratory specimen. Despite clinical alignment with hMPV pneumonia, a positive PCR result from a throat swab specimen does not necessarily indicate a lower respiratory tract infection. Conclusion Although hMPV is generally associated with acute respiratory tract infections in children, it should still be kept in mind that it can cause myocardial involvement. Compared to previously reported cases of metapneumovirus-related myocarditis, this case is the first to demonstrate a notably adverse outcome associated with the concurrent presence of bacterial infection. Abbreviations Human metapneumovirus (hMPV); medical intensive care unit (MICU); extracorporeal membrane oxygenation (ECMO); intra-aortic balloon pump (IABP); polymerase chain reaction (PCR); white blood cell (WBC); electrocardiogram (ECG); acute respiratory distress syndrome (ARDS); cardiac magnetic resonance (CMR) Declarations Ethics approval and consent to participate All methods were carried out in accordance with relevant guidelines and regulations. The study was approved by the Taipei Medical University - Joint Institutional Review Board (number: N202405091). Consent for publication Written informed consent was obtained from study participant to publish this information. Competing interests There are no fnancial or non-fnancial competing interests. Funding There is no funding source. Author Contribution Writing the original draft: S.-H.W. Reviewing & editing the draft: M.-H.L., Y.-C.L., and Y.-J.L. Supervision and project administration: M.-H.L. and Y.-C.L. All authors have read and agreed to the published version of the manuscript. Acknowledgements Not applicable. Availability of data and materials Not applicable. References van den Hoogen BG, de Jong JC, Groen J, Kuiken T, de Groot R, Fouchier RA, Osterhaus AD. A newly discovered human pneumovirus isolated from young children with respiratory tract disease. Nat Med. 2001;7(6):719–24. Kim CK, Choi J, Callaway Z, Kim HB, Chung JY, Koh YY, Shin BM. Clinical and epidemiological comparison of human metapneumovirus and respiratory syncytial virus in seoul, Korea, 2003–2008. J Korean Med Sci. 2010;25(3):342–7. Haas LE, Thijsen SF, van Elden L, Heemstra KA. Human metapneumovirus in adults. Viruses. 2013;5(1):87–110. Chen YW, Huang YC, Ho TH, Huang CG, Tsao KC, Lin TY. Viral etiology of bronchiolitis among pediatric inpatients in northern Taiwan with emphasis on newly identified respiratory viruses. J Microbiol Immunol Infect. 2014;47(2):116–21. Choi MJ, Song JY, Yang TU, Jeon JH, Noh JY, Hong KW, Cheong HJ, Kim WJ. Acute Myopericarditis caused by Human Metapneumovirus. Infect Chemother. 2016;48(1):36–40. Weinreich MA, Jabbar AY, Malguria N, Haley RW. New-Onset Myocarditis in an Immunocompetent Adult with Acute Metapneumovirus Infection. Case Rep Med 2015, 2015:814269. Wyde PR, Chetty SN, Jewell AM, Boivin G, Piedra PA. Comparison of the inhibition of human metapneumovirus and respiratory syncytial virus by ribavirin and immune serum globulin in vitro. Antiviral Res. 2003;60(1):51–9. Huang X, Sun Y, Su G, Li Y, Shuai X. Intravenous Immunoglobulin Therapy for Acute Myocarditis in Children and Adults. Int Heart J. 2019;60(2):359–65. Kitanovski L, Kopriva S, Pokorn M, Dolnicar MB, Rajic V, Stefanovic M, Jazbec J. Treatment of severe human metapneumovirus (hMPV) pneumonia in an immunocompromised child with oral ribavirin and IVIG. J Pediatr Hematol Oncol. 2013;35(7):e311–313. Ulbrandt ND, Ji H, Patel NK, Riggs JM, Brewah YA, Ready S, Donacki NE, Folliot K, Barnes AS, Senthil K, et al. Isolation and characterization of monoclonal antibodies which neutralize human metapneumovirus in vitro and in vivo. J Virol. 2006;80(16):7799–806. Choe YJ, Park S, Michelow IC. Co-seasonality and co-detection of respiratory viruses and bacteraemia in children: a retrospective analysis. Clin Microbiol Infect. 2020;26(12):1690. e1695-1690 e1698. Yakut K, Varan B, Erdogan I, Tokel K. Acute respiratory distress syndrome and myocarditis caused by human metapneumovirus in a child. 2020. Marquez-Escobar VA. Current developments and prospects on human metapneumovirus vaccines. Expert Rev Vaccines. 2017;16(5):419–31. August A, Shaw CA, Lee H, Knightly C, Kalidindia S, Chu L, Essink BJ, Seger W, Zaks T, Smolenov I, et al. Safety and Immunogenicity of an mRNA-Based Human Metapneumovirus and Parainfluenza Virus Type 3 Combined Vaccine in Healthy Adults. Open Forum Infect Dis. 2022;9(7):ofac206. 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-4478998","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":308566712,"identity":"cbb25d67-2079-45ce-a384-76e6b9d4f2d7","order_by":0,"name":"Shih-Hung Wang","email":"","orcid":"","institution":"Shuang-Ho Hospital, Taipei Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Shih-Hung","middleName":"","lastName":"Wang","suffix":""},{"id":308566713,"identity":"71bf1a32-bf53-4e46-8024-46802a9f1c3b","order_by":1,"name":"Mei-Hui Lee","email":"","orcid":"","institution":"Shuang-Ho Hospital, Taipei Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Mei-Hui","middleName":"","lastName":"Lee","suffix":""},{"id":308566714,"identity":"feb3bdf0-9a7e-46d9-8300-88f907648358","order_by":2,"name":"Yuarn-Jang Lee","email":"","orcid":"","institution":"Shuang-Ho Hospital, Taipei Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yuarn-Jang","middleName":"","lastName":"Lee","suffix":""},{"id":308566715,"identity":"f7c90793-600c-4d7c-a22f-31b75c33a77b","order_by":3,"name":"Yung-Ching Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAyUlEQVRIiWNgGAWjYBACNvbmgw8+VMC5RGjh5zmWbDjjDAMDD0wLDyEtkjNy1KR520jRYnDmDLMB77w6BnuxMwYMH8oOM9hLJBDQcrz34APJbYcZeKRzDBhnnAMyCGo5cy7ZwHDbAbAWZt42kF5CWm7kmEkkzqmDaPlLjBag980kDjYwQ7QwEqMFHMgNxw7z8NxOKzjYcy6dh+f+A/xaQFH5+E9NnRz77OSND36UWcux9xzArwUGwLFxgIGIaBkFo2AUjIJRQAQAAMoHP1ANun1tAAAAAElFTkSuQmCC","orcid":"","institution":"Shuang-Ho Hospital, Taipei Medical University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Yung-Ching","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2024-05-26 07:11:55","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4478998/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4478998/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":58244472,"identity":"4e82cde3-d559-4c93-9249-1f164243105e","added_by":"auto","created_at":"2024-06-13 02:11:42","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":144411,"visible":true,"origin":"","legend":"\u003cp\u003eChest X-ray findings showing alveolar infiltration opacity in the right lower lung (day 0), which progressed bilaterally to ARDS at our MICU (day 1, day 2).\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4478998/v1/11143406e0853c442216fe3f.jpg"},{"id":58243340,"identity":"37e8c042-027c-4f04-832b-f8156d51177b","added_by":"auto","created_at":"2024-06-13 02:03:42","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":195172,"visible":true,"origin":"","legend":"\u003cp\u003eECG showing sinus tachycardia upon arrival at our emergency room, which changed to diffuse ST-T elevation at our MICU (Day 2)\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4478998/v1/910bdc1941e9929357e718a7.jpg"},{"id":59979370,"identity":"d28f8239-989b-4807-a08d-e94d2eef275a","added_by":"auto","created_at":"2024-07-10 05:40:41","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":655372,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4478998/v1/e059bfc6-746a-48c9-8db4-099d55b1c2f1.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Myocarditis Caused by Metapneumovirus with Klebsiella pneumoniae Infection: A Case Report","fulltext":[{"header":"Background","content":"\u003cp\u003eHuman metapneumovirus (hMPV), an emerging respiratory virus first isolated in 2001 [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], has been reported worldwide. As a nonsegmented, negative-sense RNA virus [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], it primarily causes upper and lower respiratory tract infections in children [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] and threatens the health of elderly and immunocompromised individuals [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The clinical features of the illness caused by hMPV infection range from mild upper respiratory tract infection to life-threatening severe bronchiolitis and pneumonia. In Taiwan, 16.8% of children hospitalized with bronchiolitis are infected with hMPV [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. However, rare cases have highlighted hMPV infections manifesting beyond the respiratory system, including cardiac impairment. Acute myocarditis secondary to hMPV infection has only been described twice in adult case reports; this condition has a good prognosis with no other infection combined [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Here, we present a case of severe pneumonia and myocarditis caused by hMPV infection in an elderly patient. To the best of our knowledge, this is the first case of severe myocarditis caused by metapneumovirus infection detected by the FilmArray\u0026reg; Pneumonia Multiplex PCR Panel with poor outcomes.\u003c/p\u003e"},{"header":"Case presentation","content":"\u003cp\u003eThe patient was sent to our emergency room because of fever, a productive cough, and progressive dyspnea for one day. Upon arrival at our hospital, he presented with clear consciousness, tachycardia (143 beats/min), tachypnea (28 breaths/min), blood pressure within the normal range (106/88 mmHg), and fever (38.4\u0026deg;C). Neither chills, muscle soreness, nor limb weakness was noted. He had no recent travel, tick bites, or acute upper respiratory infections.\u003c/p\u003e \u003cp\u003eThe patient had underlying diabetes mellitus and hypertension and was receiving regular medical control. He also had liver cirrhosis with chronic hepatitis B infection and received 0.5 mg/d entecavir regularly. He had no history of head trauma or psychiatric or psychological disease. He had no tuberculosis or lung cancer. He was a smoker (quit for 10 years) with a drug addiction. She resides in Guangdong Province, southern China. She had no recent travel, tick bites, or acute upper respiratory infections. She had not been in direct contact with any birds, poultry or horses. She did not shop at live bird markets, nor did she have friends or relatives with pet birds.\u003c/p\u003e \u003cp\u003eOn physical examination, lung auscultation revealed crackles in the right lung fields. Laboratory tests revealed that the white blood cell (WBC) count was 3240/\u0026micro;L, with 49% neutrophils (10% of the band form) and 33% lymphocytes. Her lactate level was 12.2 mmol/L, and she exhibited metabolic acidosis and a high procalcitonin level (50.75 mg/dL). Her troponin-I concentration was 248 pg/mL, her CPK concentration was 662 U/L, and her CKMB concentration was 1.9 ng/mL. platelet was 221000/\u0026micro;L. BUN and creatinine were 39 mg/dL and 2/34 mg/dL, respectively. AST was 111 IU/L. Electrolytes were within the normal range. Urine analysis revealed amber-colored bacteria (296.6/\u0026micro;L) and no pyuria. Chest X-ray revealed alveolar infiltration in the right middle lobe (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). An electrocardiogram (ECG) showed sinus tachycardia (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Piperacillin/tazobactam (4500 mg) was administered as empiric antibiotics. His clinical condition deteriorated rapidly to septic shock with severe hypoxemia and hypotension (78/49 mmHg) during the routine examination. Non-invasive cardiac output hemodynamic monitor showed low stroke volume and low systemic vascular resistance. Epinephrine 20 mL/hr. was administered via a central vein catheter. After tracheal intubation and ventilator-assisted ventilation, he was transferred to the MICU for further treatment (on day 0). In the MICU, arterial blood gas analysis initially revealed a pH of 7.322, PO2 of 315.3 mmHg, PCO2 of 23.3 mmHg, HCO3 of 11.8 mmol/L and FiO2 of 60%. Due to persistent hypotension (75/51 mmHg), an infusion of vasopressin and adrenaline was added. With progressive dyspnea, arterial blood gas analysis revealed a pH of 7.23, PO2 of 114.2 mmHg, PCO2 of 46.2 mmHg, HCO3 of 18.9 mmol/L and FiO2 of 100%. Chest X-ray revealed cardiomegaly and progressive infiltration in the bilateral lung, which indicated progressive pneumonia with ARDS. On the next day (day 1), the WBC count was 3070/\u0026micro;L. BUN and creatinine were 38 mg/dL and 1.78 mg/dL, respectively. Her AST level increased to 2035 IU/L, and her ALT level was 679 IU/L. Troponin-I (2167 pg/mL), CPK (3319 U/L), and CKMB (182 mg/dL) were elevated. The lactate concentration was 18.1 mmol/L (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). ECG revealed diffuse S-T elevation. ECMO was performed at the right femoral artery and right femoral vein. Cardiac echocardiography revealed an left ventricular ejection fraction of 15% with global left ventricular hypokinesis and blood stasis within the LV, which indicated acute heart failure with reduced ejection fraction, suspected stress cardiomyopathy and myocarditis. A coronary angiography was performed to rule out acute myocardial infarction and showed no significant vessel obstruction. IABP was inserted into the descending aorta. However, the patient ultimately died 2 days after admission.\u003c/p\u003e \u003cp\u003eConcerning the presence of the pathogen, the results of two sets of peripheral blood cultures and urine cultures during episodes of fever were negative. The film array multiplex panel showed negative findings for parainfluenza virus (types 1\u0026ndash;4), adenovirus, rhinovirus, enterovirus, \u003cem\u003eMycoplasma pneumoniae\u003c/em\u003e, Bordetella parapertusis, and \u003cem\u003eBordetella pertussis\u003c/em\u003e; however, hMPV was positive. Moreover, sputum culture revealed the pathogen \u003cem\u003eKlebsiella pneumoniae\u003c/em\u003e with KeyMyth Klbsiella pneumoniae Serotype 1 (Key Myth Biotech, Co. Ltd. Taiwan). The final diagnoses were infection with \u003cem\u003eKlebsiella pneumoniae\u003c/em\u003e and metapneumovirus, severe community-acquired pneumonia, type I respiratory failure, acute respiratory distress syndrome (ARDS), and myocarditis.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eInitial laboratory findings\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDay 0\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDay 2\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWBC (count/uL)\u003c/p\u003e \u003cp\u003eNeutrophil (band)\u003c/p\u003e \u003cp\u003eLymphocyte\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3240\u003c/p\u003e \u003cp\u003e49% (10%) \u003c/p\u003e \u003cp\u003e33%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3070\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHb (g/dL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePlatelet (count/uL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e221000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBUN (mg/dL)\u003c/p\u003e \u003cp\u003eCreatinine (mg/dL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9\u003c/p\u003e \u003cp\u003e2.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38\u003c/p\u003e \u003cp\u003e1.78\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProcalcitonin (ng/mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e50.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBNP (pg/mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e44.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTroponin-I (pg/mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e248.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33328.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCKMB (ng/mL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e182\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCPK (U/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e662\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3319\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGOT (IU/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e111\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2035\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal bilirubin (mg/dL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDirect bilirubin (mg/dL)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLactate (mmol/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNa (mmol/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e136\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e145\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eK (mmol/L)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCl (mmol/L))\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e103\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e106\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion and conclusions","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003ehMPV infection in the myocardium\u003c/h2\u003e \u003cp\u003eAlthough hMPV infection mostly manifests via the upper and lower respiratory tract, several case reports of myocarditis caused by hMPV infection in children, elderly individuals and immunocompromised patients have been published. Compared to influenza and RSV infections, hMPV infection is more commonly associated with cardiovascular disease. Although hMPV has been identified as one of the etiologic agents of acute myocarditis, the detailed mechanism is still unclear, as is whether the virus has a tropism for the myocardium or whether patients with underlying cardiovascular disease are more vulnerable to hMPV. Acute myocarditis secondary to hMPV infection has only been described twice in adult patients who have a good prognosis with no other pathogen infection combined. In the present case, we revealed a poor prognosis in patients with hMPV myocarditis complicated with severe ARDS and concurrent infection with \u003cem\u003eKlebsiella pneumoniae\u003c/em\u003e.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eTreatment with hMPV\u003c/h3\u003e\n\u003cp\u003eThe treatment approach for hMPV primarily involves supportive care and may vary based on different clinical presentations. Certain drugs, such as ribavirin, have shown potential antiviral activity against hMPV \u003cem\u003ein vitro\u003c/em\u003e [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] but still lack large-scale clinical efficacy data [28,29]. A meta-analysis provided some supportive evidence for IVIG therapy in acute myocarditis patients, but the role of anti-inflammatory therapy, IVIG, steroids, and antiviral therapy in hMPV myocarditis is still unclear [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. There have been case reports and \u003cem\u003ein vitro\u003c/em\u003e studies exploring antiviral therapies such as immunoglobulins or monoclonal antibodies [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. However, the exact efficacy of these treatments still requires further evaluation. The rate of concurrent bacterial lung infections or bacteremia is greater in children infected with hMPV [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] than in those infected with RSV. In the case of hMPV, antibiotics tend to be administered because of concerns regarding concomitant bacterial pneumonia even if a bacterial pathogen is ultimately not isolated [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In prevention, in addition to enhancing personal hygiene and decreasing infection exposure, several vaccines are currently in development for preventing hMPV infection [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. These vaccines primarily target the F protein of hMPV, inducing an immune response to enhance immunity against hMPV. Further research is needed to assess the safety and efficacy of these vaccines. In addition to live attenuated and subunit protein vaccines undergoing trial development, there is ongoing development of mRNA vaccines, which have completed phase 1 clinical trials, demonstrating safety and immunogenicity in healthy adults [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eInitially, safety concerns precluded the acquisition of myocardial and pericardial biopsies, rendering the pathologic confirmation of myopericarditis diagnosis unattainable. Additionally, cardiac magnetic resonance (CMR) imaging was omitted in this instance. CMR imaging is recognized as a pivotal diagnostic tool for myocarditis that effectively distinguishes between ischemic and nonischaemic cardiomyopathy. In this case, coronary angiography revealed unremarkable coronary arteries without significant vessel obstruction, which decreased the possibility of myocardial infarction. Furthermore, the absence of bronchoscopy limited respiratory virus PCR to an upper respiratory specimen. Despite clinical alignment with hMPV pneumonia, a positive PCR result from a throat swab specimen does not necessarily indicate a lower respiratory tract infection.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAlthough hMPV is generally associated with acute respiratory tract infections in children, it should still be kept in mind that it can cause myocardial involvement. Compared to previously reported cases of metapneumovirus-related myocarditis, this case is the first to demonstrate a notably adverse outcome associated with the concurrent presence of bacterial infection.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eHuman metapneumovirus (hMPV); medical intensive care unit (MICU); extracorporeal membrane oxygenation (ECMO); intra-aortic balloon pump (IABP); polymerase chain reaction (PCR); white blood cell (WBC); electrocardiogram (ECG); acute respiratory distress syndrome (ARDS); cardiac magnetic resonance (CMR)\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003eAll methods were carried out in accordance with relevant guidelines and regulations. The study was approved by the Taipei Medical University - Joint Institutional Review Board (number: N202405091).\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eWritten informed consent was obtained from study participant to publish this information.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThere are no fnancial or non-fnancial competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThere is no funding source.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eWriting the original draft: S.-H.W. Reviewing \u0026amp; editing the draft: M.-H.L., Y.-C.L., and Y.-J.L. Supervision and project administration: M.-H.L. and Y.-C.L. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003evan den Hoogen BG, de Jong JC, Groen J, Kuiken T, de Groot R, Fouchier RA, Osterhaus AD. A newly discovered human pneumovirus isolated from young children with respiratory tract disease. Nat Med. 2001;7(6):719\u0026ndash;24.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim CK, Choi J, Callaway Z, Kim HB, Chung JY, Koh YY, Shin BM. Clinical and epidemiological comparison of human metapneumovirus and respiratory syncytial virus in seoul, Korea, 2003\u0026ndash;2008. J Korean Med Sci. 2010;25(3):342\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaas LE, Thijsen SF, van Elden L, Heemstra KA. Human metapneumovirus in adults. Viruses. 2013;5(1):87\u0026ndash;110.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen YW, Huang YC, Ho TH, Huang CG, Tsao KC, Lin TY. Viral etiology of bronchiolitis among pediatric inpatients in northern Taiwan with emphasis on newly identified respiratory viruses. J Microbiol Immunol Infect. 2014;47(2):116\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChoi MJ, Song JY, Yang TU, Jeon JH, Noh JY, Hong KW, Cheong HJ, Kim WJ. Acute Myopericarditis caused by Human Metapneumovirus. Infect Chemother. 2016;48(1):36\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWeinreich MA, Jabbar AY, Malguria N, Haley RW. New-Onset Myocarditis in an Immunocompetent Adult with Acute Metapneumovirus Infection. \u003cem\u003eCase Rep Med\u003c/em\u003e 2015, 2015:814269.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWyde PR, Chetty SN, Jewell AM, Boivin G, Piedra PA. Comparison of the inhibition of human metapneumovirus and respiratory syncytial virus by ribavirin and immune serum globulin in vitro. Antiviral Res. 2003;60(1):51\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang X, Sun Y, Su G, Li Y, Shuai X. Intravenous Immunoglobulin Therapy for Acute Myocarditis in Children and Adults. Int Heart J. 2019;60(2):359\u0026ndash;65.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKitanovski L, Kopriva S, Pokorn M, Dolnicar MB, Rajic V, Stefanovic M, Jazbec J. Treatment of severe human metapneumovirus (hMPV) pneumonia in an immunocompromised child with oral ribavirin and IVIG. J Pediatr Hematol Oncol. 2013;35(7):e311\u0026ndash;313.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUlbrandt ND, Ji H, Patel NK, Riggs JM, Brewah YA, Ready S, Donacki NE, Folliot K, Barnes AS, Senthil K, et al. Isolation and characterization of monoclonal antibodies which neutralize human metapneumovirus in vitro and in vivo. J Virol. 2006;80(16):7799\u0026ndash;806.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChoe YJ, Park S, Michelow IC. Co-seasonality and co-detection of respiratory viruses and bacteraemia in children: a retrospective analysis. Clin Microbiol Infect. 2020;26(12):1690. e1695-1690 e1698.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYakut K, Varan B, Erdogan I, Tokel K. Acute respiratory distress syndrome and myocarditis caused by human metapneumovirus in a child. 2020.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMarquez-Escobar VA. Current developments and prospects on human metapneumovirus vaccines. Expert Rev Vaccines. 2017;16(5):419\u0026ndash;31.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAugust A, Shaw CA, Lee H, Knightly C, Kalidindia S, Chu L, Essink BJ, Seger W, Zaks T, Smolenov I, et al. Safety and Immunogenicity of an mRNA-Based Human Metapneumovirus and Parainfluenza Virus Type 3 Combined Vaccine in Healthy Adults. Open Forum Infect Dis. 2022;9(7):ofac206.\u003c/span\u003e\u003c/li\u003e\u003c/ol\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":"Metapneumovirus, Klebsiella pneumoniae, Myocarditis","lastPublishedDoi":"10.21203/rs.3.rs-4478998/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4478998/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground\u003c/strong\u003e Human metapneumovirus (hMPV), classified in the Pneumoviridae family, primarily causes lower respiratory tract infections in children and immunocompromised individuals. However, rare cases have highlighted hMPV infections manifesting beyond the respiratory system, including cardiac impairment.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCase presentation \u003c/strong\u003eWe report the case of a 68-year-old man who presented at the emergency room with dyspnea and fever and who rapidly progressed to septic shock with increasing oxygen requirements, necessitating transfer to the medical intensive care unit (MICU). Diagnostic evaluations comprising cardiac echocardiography and coronary angiography were utilized to confirmmyocarditis while ruling out acute myocardial infarction. Despite the implementation of extracorporeal membrane oxygenation (ECMO) and intra-aortic balloon pump (IABP)therapy, the patient succumbed to the illness three days after admission to the MICU. Polymerase chain reaction (PCR) of a throat swab confirmed the diagnosis of Metapneumovirus infection, and \u003cem\u003eKlebsiella pneumoniae\u003c/em\u003e was concurrently detected through sputum culture.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions \u003c/strong\u003eCompared to previously reported cases of metapneumovirus-related myocarditis, this case is the first to demonstrate a notably adverse outcome associated with the concurrent presence of bacterial infection.\u003c/p\u003e","manuscriptTitle":"Myocarditis Caused by Metapneumovirus with Klebsiella pneumoniae Infection: A Case Report","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-13 02:03:37","doi":"10.21203/rs.3.rs-4478998/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":"f0235070-7aff-4f6f-97df-8198981390c9","owner":[],"postedDate":"June 13th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-07-10T05:32:35+00:00","versionOfRecord":[],"versionCreatedAt":"2024-06-13 02:03:37","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4478998","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4478998","identity":"rs-4478998","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}