Scrotal Abscess Caused by Ignavigranum ruoffiae: A Case Report and Literature Review

Scrotal Abscess Caused by Ignavigranum ruoffiae: A Case Report and Literature Review | 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 Scrotal Abscess Caused by Ignavigranum ruoffiae: A Case Report and Literature Review Kaixuan Zhang, Sudi Zhu, Mengyu Zhang, Huihui Li, Yuanyuan Xu, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9234385/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Background: Ignavigranum ruoffiae is a rare catalase-negative, facultatively anaerobic Gram-positive coccus. Published human infections remain exceptionally uncommon and have mainly involved localized suppurative disease at non-genitourinary sites. To our knowledge, scrotal involvement has not been reported previously. Case Report: A 63-year-old man presented with a 2-day history of progressive painful swelling of the left scrotum and inguinal region. Systemic inflammatory findings were not striking on admission, with a white blood cell count of 9.27 × 10^9/L and a procalcitonin level of 0.08 ng/mL. Scrotal ultrasonography demonstrated a 21 × 12 × 18 mm heterogeneous lesion in the left inguinal-scrotal region. Empirical intravenous levofloxacin was started after admission. On hospital day 2, the patient developed a transient fever of 38.0 °C, and the lesion ruptured spontaneously. Needle aspiration drainage yielded approximately 5 mL of gray-white pus. Culture showed pure growth of small gray-white colonies on sheep blood agar. Gram staining demonstrated Gram-positive coccoid organisms arranged in pairs and short chains. The isolate was identified as I. ruoffiae by MALDI-TOF MS using a Bruker microflex LT/SH system (score 2.40) and was further confirmed by 16S rRNA gene sequencing. MICs were generated using the VITEK 2 system. The isolate showed low MICs for beta-lactams and in vitro activity of levofloxacin, although categorical interpretation was made cautiously because species-specific breakpoints are unavailable. On hospital day 5, treatment was changed to intravenous amoxicillin/clavulanate (1.2 g every 8 h). The patient improved steadily thereafter. By discharge on hospital day 13, scrotal swelling had resolved, the wound bed showed healthy granulation tissue, and no purulent discharge remained. Oral amoxicillin/clavulanate was prescribed at discharge. At 1-month and 3-month follow-up, the patient remained asymptomatic, with no clinical evidence of recurrence. Conclusions : This case broadens the known anatomical spectrum of I. ruoffiae infection by documenting scrotal abscess. The report also shows that localized suppurative infection may occur despite minimal systemic inflammatory response. In vitro susceptibility did not fully predict bedside response before drainage, underscoring the importance of source control and careful microbiological recognition. Ignavigranum ruoffiae scrotal abscess 16S rRNA MALDI-TOF MS rare pathogen source control Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Ignavigranum ruoffiae ( I. ruoffiae ) is a rare catalase-negative, facultatively anaerobic Gram-positive coccus within the family Aerococcaceae. The species was first described in 1999 from human clinical specimens, and only a small number of clinically relevant human isolates have since been reported[ 1 , 2 ]. Most published infections have involved localized suppurative disease, including wound infection, ear abscess, skin abscess, and an infected breast cyst[ 3 ]. Recognition of this organism in routine practice remains limited. Rare catalase-negative Gram-positive cocci are prone to misidentification when laboratories rely only on conventional phenotypic methods[ 4 ]. MALDI-TOF MS has improved the recognition of unusual clinical isolates, and 16S rRNA gene sequencing remains valuable when uncommon pathogens are recovered from clinically significant specimens[ 5 ]. Scrotal abscess caused by I. ruoffiae has not, to our knowledge, been reported previously[ 2 ]. This report describes a 16S rRNA-confirmed scrotal abscess caused by I. ruoffiae and places the case in the context of the limited published literature. 2. Case Report A 63-year-old man was admitted to the Department of Urology on 26 December 2025 with a 2-day history of progressive pain and swelling involving the left scrotum and inguinal region. He denied preceding trauma. His medical history included hypertension, severe traumatic brain injury in September 2024, decompressive craniectomy, and subsequent cranioplasty in August 2025. At presentation, physical examination showed a tender erythematous swelling extending from the left scrotum toward the inguinal region. The overlying skin was intact, and fluctuation was equivocal, suggesting either a tense abscess cavity or an inflammatory phlegmon-like stage. The patient was afebrile on admission. Initial laboratory testing showed a white blood cell count of 9.27 × 10^ 9 /L and a procalcitonin level of 0.08 ng/mL. These findings did not indicate a marked systemic inflammatory response. Scrotal ultrasonography demonstrated a heterogeneous lesion in the left inguinal-scrotal region measuring approximately 21 × 12 × 18 mm, with peripheral blood-flow signals. Bilateral epididymal echogenic heterogeneity and left testicular calcification were also reported (Fig. 1 ). Empirical intravenous levofloxacin (0.5 g once daily) was initiated after admission. On hospital day 2, the patient developed a transient fever of 38.0°C, and the lesion ruptured spontaneously with discharge of gray-white purulent material. Needle aspiration drainage was then performed through the rupture site, yielding approximately 5 mL of gray-white pus. Local pain improved after drainage, and the patient became afebrile thereafter. Microbiological examination of the aspirated material showed pure growth of small gray-white colonies on sheep blood agar after 48 h of incubation. Gram staining of colony material demonstrated Gram-positive coccoid organisms arranged in pairs and short chains (Fig. 2 ). MALDI-TOF MS identified the isolate as I. ruoffiae using a Bruker Daltonics microflex LT/SH system, with a score of 2.40. Species identification was further confirmed by 16S rRNA gene sequencing using GenBank reference sequence CP096206.2. Detailed microbiological identification and antimicrobial susceptibility testing results are summarized in Tables 1 and 2 . Table 1 Microbiological identification of the isolate from the scrotal abscess. Category Method Result Interpretation / Comment Direct smear / colony Gram stain Gram staining Gram-positive coccoid organisms Arranged in pairs and short chains Culture morphology Sheep blood agar Small gray-white colonies Pure growth after 48 h of incubation MALDI-TOF MS Bruker Daltonics microflex LT/SH Score: 2.40 High-confidence identification as I. ruoffiae 16S rRNA gene sequencing Hefei Anweikang Medical Laboratory I. ruoffiae (> 99% match) Species confirmation Sequence reference GenBank CP096206.2 Reference sequence used for confirmation Specimen source Pus aspirate from left scrotal lesion Positive culture Clinically significant isolate Table 2 Antimicrobial susceptibility testing results of the isolate. Antimicrobial Class Antimicrobial Agent MIC (mg/L) Zone Diameter (mm) Interpretation Guideline / Comment Beta-lactams Penicillin G ≤ 0.06 30 S* CLSI M45 / surrogate CLSI M100 criteria Ampicillin ≤ 0.12 NT S* CLSI M45 / surrogate CLSI M100 criteria Amoxicillin/clavulanate ≤ 0.12/0.06 32 S* CLSI M45 / surrogate CLSI M100 criteria Ceftriaxone 0.25 NT S* CLSI M45 / surrogate CLSI M100 criteria Fluoroquinolones Levofloxacin 0.5 28 S* CLSI M45 / surrogate CLSI M100 criteria Ciprofloxacin 1.0 NT S* CLSI M45 / surrogate CLSI M100 criteria Macrolides Erythromycin 0.12 NT S* CLSI M45 / surrogate CLSI M100 criteria Lincosamides Clindamycin ≤ 0.06 NT S* CLSI M45 / surrogate CLSI M100 criteria Glycopeptides Vancomycin 0.5 NT S* CLSI M45 / surrogate CLSI M100 criteria Oxazolidinones Linezolid 1.0 NT S* CLSI M45 / surrogate CLSI M100 criteria Note: Zone diameters from the initial disk diffusion test are provided for the empirically used antibiotics. * Because validated species-specific breakpoints for I. ruoffiae are unavailable, categorical interpretations were inferred cautiously using surrogate criteria for viridans group streptococci from CLSI M100 where applicable. MICs were generated using the VITEK 2 system, and disk diffusion zone diameters were recorded for the empirically used agents. Antimicrobial susceptibility testing was interpreted with reference to CLSI M45; because validated species-specific breakpoints for I. ruoffiae are unavailable, categorical interpretations were inferred cautiously using surrogate criteria for viridans group streptococci from CLSI M100 where applicable. The isolate showed low MICs for penicillin G, ampicillin, amoxicillin/clavulanate, and ceftriaxone. Levofloxacin also demonstrated in vitro activity. Although the isolate appeared susceptible to levofloxacin in vitro, the bedside course during the pre-drainage phase was unsatisfactory because fever and spontaneous rupture developed before effective source control had been established. On hospital day 5, antimicrobial therapy was changed to intravenous amoxicillin/clavulanate (1.2 g every 8 h). The patient improved steadily after drainage and beta-lactam therapy. By discharge on hospital day 13, the scrotal swelling had resolved, the wound bed showed healthy granulation tissue, and no purulent discharge remained. Oral amoxicillin/clavulanate (875 mg/125 mg, twice daily) was prescribed at discharge. At the 1-month and 3-month outpatient follow-up visits, the patient remained asymptomatic, and no clinical evidence of recurrence was observed (Fig. 3 ). 3. Discussion This case broadens the known anatomical spectrum of I. ruoffiae infection. Published reports have so far involved wound infection, ear abscess, skin abscess, and an infected breast cyst[ 1 – 3 ]. Scrotal involvement has not, to our knowledge, been described previously. That distinction matters in practice because unusual site involvement influences whether a rare isolate is dismissed as contamination or recognized as a true pathogen[ 4 ]. Comparison with previous reports helps place the present case in context (Table 3 ). Despite differences in anatomical site, the published cases and the current case share several features: localized purulent disease, the need for careful laboratory identification, and favorable outcomes when active antimicrobial therapy was combined with drainage or other forms of source control when required[ 6 ]. The depth and location of the present lesion, however, made early clinical recognition more challenging than in superficial abscesses. The case also shows that minimal systemic inflammatory abnormalities do not exclude clinically relevant suppuration. Table 3 Published human reports involving Ignavigranum ruoffiae. Study Clinical Source / Site Identification Method Management Main Relevance Collins et al. [ 1 ] Wound infection / ear abscess Phenotypic methods + 16S rRNA Descriptive taxonomic report Original species description De Paulis et al. [ 2 ] Skin abscess Phenotypic methods + 16S rRNA Drainage + antimicrobial therapy Localized suppurative infection Merlino et al. [ 3 ] Skin abscess Clinical microbiology identification Case-based management Supports pathogenic role in soft tissue abscess Suchan et al. [ 4 ] Infected breast cyst Whole-genome sequencing Descriptive microbiological report Expands human suppurative spectrum Present case Scrotal abscess MALDI-TOF MS + 16S rRNA Drainage + beta-lactam therapy First reported scrotal involvement Several practical lessons for clinical recognition and microbiology workflow emerge from this case. First, clinicians should not dismiss the possibility of abscess formation solely because the white blood cell count and procalcitonin level are not markedly elevated[ 7 ]. Second, recovery of an unusual catalase-negative Gram-positive coccus from a clinically significant purulent specimen should prompt full identification rather than dismissal as contamination[ 8 ]. Third, MALDI-TOF MS can provide rapid presumptive identification, while confirmatory sequencing remains useful when rare isolates are recovered from clinically important specimens[ 9 ]. These steps may reduce the risk of under-recognition of uncommon pathogens in routine microbiology practice. The case highlights that in vitro susceptibility may not predict response before drainage. The isolate showed low MICs for beta-lactams and in vitro activity to levofloxacin, yet fever and spontaneous rupture developed during the pre-drainage phase. Several factors could explain that mismatch, including limited drug penetration into an undrained abscess cavity, a high local bacterial burden, the inoculum effect, and altered antimicrobial activity in acidic or protein-rich purulent material[ 10 – 12 ]. The decision to change to amoxicillin/clavulanate after drainage was therefore made as a pragmatic clinical adjustment supported by the susceptibility profile rather than as proof of beta-lactam superiority. The route of acquisition remains uncertain. A hypothetical illustration summarizing the possible route of infection and the clinical interpretation of treatment response is shown in Fig. 4 . A history of oral-genital sexual exposure raises the possibility of direct mucocutaneous inoculation. However, the absence of visible skin disruption and the relatively deep inguinoscrotal location of the lesion make a purely superficial inoculation pathway difficult to establish with confidence. An alternative explanation is transient bacteremia with secondary seeding of a site of reduced local resistance[ 13 ]. In this regard, the ultrasonographic findings of left testicular calcification and bilateral epididymal echogenic heterogeneity may suggest pre-existing local abnormalities that could have favored localization. Hematogenous dissemination may therefore be biologically more plausible than direct inoculation in this setting, although neither route can be proven in the absence of blood cultures, paired oral cultures, partner samples, or molecular linkage data[ 14 ]. This report has limitations. It describes a single patient and cannot establish broad conclusions regarding virulence or optimal therapy. The exact route of infection was not proven. Species identification was strengthened by MALDI-TOF MS and 16S rRNA sequencing, but antimicrobial susceptibility interpretation remained imperfect because species-specific breakpoints are unavailable[ 15 ]. Even so, the case remains informative because it documents a rare pathogen at an unreported anatomical site and illustrates the importance of careful laboratory recognition and source control. 4. Conclusions This case documents, to our knowledge, the first reported scrotal abscess caused by I. ruoffiae . The report broadens the recognized anatomical spectrum of infection associated with this uncommon organism. Minimal systemic inflammatory abnormalities did not exclude clinically significant localized suppuration. Accurate laboratory identification, cautious interpretation of susceptibility data, and timely source control were central to successful management. Abbreviations I. ruoffiae Ignavigranum ruoffiae MALDI-TOF MS matrix-assisted laser desorption/ionization time-of-flight mass spectrometry 16S rRNA 16S ribosomal RNA MIC minimum inhibitory concentration AST antimicrobial susceptibility testing WBC white blood cell count PCT procalcitonin CLSI Clinical and Laboratory Standards Institute IRB Institutional Review Board NT not tested VITEK 2 VITEK 2 automated microbiology system KB Kirby–Bauer disk diffusion test Declarations Author Contributions Conceptualization, Kaixuan Zhang and Zhikang Wang; methodology, Sudi Zhu; software, Mengyu Zhang; formal analysis, Kaixuan Zhang; data curation, Huihui Li; writing—original draft preparation, Sudi Zhu; writing—review and editing, Kaixuan Zhang and Pingping Zhao. All authors have read and agreed to the published version of the manuscript. Funding This research was funded by Science and Technology Bureau of Suzhou City, grant number SZZCXM202522. Institutional Review Board Statement The study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of Wanbei Coal Electric Group General Hospital (protocol code: 2026-031). Informed Consent Statement Written informed consent for publication of the clinical details and accompanying images was obtained from the patient. Data Availability Statement The datasets used and/or analysed during the current study are not publicly available due to patient privacy and institutional restrictions. They are available from the corresponding author on reasonable request. Acknowledgments The authors are grateful to Wanbei Coal Electric Group General Hospital for its support of this work. Conflicts of Interest The authors declare that there is no conflict of interest. References COLLINS MD, LAWSON PA, MONASTERIO R et al. Ignavigranum ruoffiae sp. nov., isolated from human clinical specimens. Int J Syst Bacteriol 1999; 49 Pt 1: 97–101. 10.1099/00207713-49-1-97 DE PAULIS AN BERTONAE, GUTIéRREZ MA, et al. Ignavigranum ruoffiae, a rare pathogen that caused a skin abscess. JMM Case Rep. 2018;5(2):e005137. 10.1099/jmmcr.0.005137 . MERLINO J, BIRDSALL J, BASKAR SR, et al. Ignavigranum ruoffiae associated with skin abscess. Pathology. 2022;54(1):125–6. 10.1016/j.pathol.2021.03.009 . SUCHAN DM, LOOS KD, MACKENZIE KD, et al. A Complete Whole-Genome Sequence of Ignavigranum ruoffiae Strain CPL 242382-20, an Opportunistic Human Pathogen Recovered from a Breast Cyst. Microbiol Resour Announc. 2023;12(1):e0052122. 10.1128/mra.00521-22 . RUOFF KL. Miscellaneous catalase-negative, gram-positive cocci: emerging opportunists. J Clin Microbiol. 2002;40(4):1129–33. 10.1128/jcm.40.4.1129-1133.2002 . FACKLAM R. Identification, classification, and clinical relevance of catalase-negative, gram-positive cocci, excluding the streptococci and enterococci. Clin Microbiol Rev. 1995;8(4):479–95. 10.1128/cmr.8.4.479 . BIZZINI A, JATON K, ROMO D, et al. Matrix-assisted laser desorption ionization-time of flight mass spectrometry as an alternative to 16S rRNA gene sequencing for identification of difficult-to-identify bacterial strains. J Clin Microbiol. 2011;49(2):693–6. 10.1128/jcm.01463-10 . LACLAIRE LL, FACKLAM RR. Comparison of three commercial rapid identification systems for the unusual gram-positive cocci Dolosigranulum pigrum, Ignavigranum ruoffiae, and Facklamia species. J Clin Microbiol. 2000;38(6):2037–42. 10.1128/jcm.38.6.2037-2042.2000 . CHRISTENSEN JJ, DARGIS R, HAMMER M, et al. Matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis of Gram-positive, catalase-negative cocci not belonging to the Streptococcus or Enterococcus genus and benefits of database extension. J Clin Microbiol. 2012;50(5):1787–91. 10.1128/jcm.06339-11 . RAMAREDDY RS ALLADIA. Scrotal abscess: Varied etiology, associations, and management. J Indian Assoc Pediatr Surg. 2016;21(4):164–8. 10.4103/0971-9261.186545 . LENHARD ZP JR. Inoculum effect of β-lactam antibiotics. J Antimicrob Chemother. 2019;74(10):2825–43. 10.1093/jac/dkz226 . CANCELA COSTA A, GRASS F, ANDRES CANO I, et al. Antibacterial and antifungal drug concentrations in intra-abdominal abscesses: a prospective clinical study. Antimicrob Agents Chemother. 2025;69(1):e0117824. 10.1128/aac.01178-24 . TAN J, TIAN M, ZHAO F, et al. An Investigation of the Male Genitourinary Abscess Originated from Urinary Tract in a Tertiary Hospital, Shanghai, China, from 2004 to 2019. Infect Drug Resist. 2021;14(1):795–803. 10.2147/idr.S298250 . CALDERARO A, MALDI-TOF MS CHEZZIC. A Reliable Tool in the Real Life of the Clinical Microbiology Laboratory. Microorganisms. 2024;12(2). 10.3390/microorganisms12020322 . MOGLE BT, STEELE JM, THOMAS SJ, et al. Clinical review of delafloxacin: a novel anionic fluoroquinolone. J Antimicrob Chemother. 2018;73(6):1439–51. 10.1093/jac/dkx543 . Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 30 Apr, 2026 Reviews received at journal 15 Apr, 2026 Reviewers agreed at journal 14 Apr, 2026 Reviews received at journal 14 Apr, 2026 Reviewers agreed at journal 01 Apr, 2026 Reviewers invited by journal 01 Apr, 2026 Editor invited by journal 29 Mar, 2026 Editor assigned by journal 27 Mar, 2026 Submission checks completed at journal 27 Mar, 2026 First submitted to journal 26 Mar, 2026 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-9234385","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":616991118,"identity":"37ed91e2-f4f4-4581-9607-6ab8a52dbc85","order_by":0,"name":"Kaixuan Zhang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA2UlEQVRIie3RIQvCQBTA8XcIZ3lgnQy2YBZOBqIg+gX8EDcEk4hgsTmxzq6wbyEsnzxY2syrFtOCtkUXNe1sgvfvP97dewAm0w/WAlJUltbWbe6VHmnvEp9YOJK9MJF6RFDaIeBzCflUaL4sSYFWSEt2xGdewNjpBjWChZmi44DWTftwHkYw8/qqhjSsq1SIxHZRFtsIyo/rCHcLoZATC/LFXY8gpIKQz/2KcD1iQSIvp3DkVUv2hpHQ+MtEET0epeVUp7zlxWbs1JLPkah7mjfyrTCZTKa/6AXPzUxRn24R2wAAAABJRU5ErkJggg==","orcid":"","institution":"Wanbei Coal Electric Group General Hospital","correspondingAuthor":true,"prefix":"","firstName":"Kaixuan","middleName":"","lastName":"Zhang","suffix":""},{"id":616991119,"identity":"e0073ba9-e123-4d0b-92ef-50ec107e06c9","order_by":1,"name":"Sudi Zhu","email":"","orcid":"","institution":"Wanbei Coal Electric Group General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Sudi","middleName":"","lastName":"Zhu","suffix":""},{"id":616991120,"identity":"06cb569a-c7eb-4a98-acd3-c6b6bd1cb1d6","order_by":2,"name":"Mengyu Zhang","email":"","orcid":"","institution":"Wanbei Coal Electric Group General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mengyu","middleName":"","lastName":"Zhang","suffix":""},{"id":616991121,"identity":"c5c8bbeb-fe38-4a83-8712-c05af5f17fdb","order_by":3,"name":"Huihui Li","email":"","orcid":"","institution":"Wanbei Coal Electric Group General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Huihui","middleName":"","lastName":"Li","suffix":""},{"id":616991122,"identity":"3ea82152-2693-4df8-9b04-18b33b12fdee","order_by":4,"name":"Yuanyuan Xu","email":"","orcid":"","institution":"Wanbei Coal Electric Group General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yuanyuan","middleName":"","lastName":"Xu","suffix":""},{"id":616991123,"identity":"d7f4528b-4cd7-4f7c-982d-95e9a0187869","order_by":5,"name":"Pingping Zhao","email":"","orcid":"","institution":"Wanbei Coal Electric Group General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Pingping","middleName":"","lastName":"Zhao","suffix":""},{"id":616991124,"identity":"f0c5b524-2e7a-489a-a9f5-6c1b2a55d92d","order_by":6,"name":"Zhikang Wang*","email":"","orcid":"","institution":"Wanbei Coal Electric Group General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Zhikang","middleName":"","lastName":"Wang*","suffix":""}],"badges":[],"createdAt":"2026-03-26 12:54:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9234385/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9234385/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":106307637,"identity":"865c34f4-cda8-4a8b-a050-0ba33c364796","added_by":"auto","created_at":"2026-04-07 10:06:06","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":4700865,"visible":true,"origin":"","legend":"\u003cp\u003eScrotal ultrasonography at admission. Ultrasonography demonstrated a heterogeneous hypoechoic lesion measuring approximately 21 × 12 × 18 mm in the left inguinal-scrotal region, with peripheral blood-flow signals, consistent with localized inflammatory abscess formation.\u003c/p\u003e","description":"","filename":"figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9234385/v1/18c751ec73f4bbda3cb184d2.jpg"},{"id":106403089,"identity":"0b320fb5-bb02-4647-96c0-0e8dd3eb8ee6","added_by":"auto","created_at":"2026-04-08 09:13:31","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":14423600,"visible":true,"origin":"","legend":"\u003cp\u003eColony morphology on sheep blood agar and Gram stain of colony material. (A) Culture of aspirated pus yielded pure growth of small gray-white colonies after 48 h of incubation; (B) Gram staining demonstrated Gram-positive coccoid organisms arranged in pairs and short chains.\u003c/p\u003e","description":"","filename":"figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9234385/v1/6901398fc64aa26b19b521c9.jpg"},{"id":106403300,"identity":"0352dbfd-2ff5-4fe8-9ea4-444074f80bbd","added_by":"auto","created_at":"2026-04-08 09:14:01","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":8580275,"visible":true,"origin":"","legend":"\u003cp\u003eClinical timeline of the present case. The timeline summarizes symptom onset, admission findings, empirical levofloxacin therapy, spontaneous rupture with needle aspiration drainage, microbiological identification, antimicrobial modification, and discharge.\u003c/p\u003e","description":"","filename":"figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9234385/v1/e4c6598ac1bdd8b928168735.jpg"},{"id":106403760,"identity":"b235fbdd-241a-4531-9a84-1f38da18fcfa","added_by":"auto","created_at":"2026-04-08 09:14:55","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1817915,"visible":true,"origin":"","legend":"\u003cp\u003eHypothetical illustration of the possible route of infection and interpretation of clinical response in the present case. (A) A possible route of acquisition is illustrated. Direct mucocutaneous inoculation and hematogenous dissemination are both considered possible, but neither route can be proven. (B) The figure summarizes the clinical observation that early response before drainage did not fully parallel in vitro susceptibility, whereas improvement followed source control and beta-lactam therapy.\u003c/p\u003e","description":"","filename":"figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9234385/v1/f4258c8a0c45f224bfd87e6f.jpg"},{"id":106405972,"identity":"d13a18e0-4394-44f0-a795-06a4c06160fb","added_by":"auto","created_at":"2026-04-08 09:29:11","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":30151903,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9234385/v1/9a613039-856e-46ac-a300-3108950aa5c7.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Scrotal Abscess Caused by Ignavigranum ruoffiae: A Case Report and Literature Review","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003e \u003cem\u003eIgnavigranum ruoffiae\u003c/em\u003e(\u003cem\u003eI. ruoffiae\u003c/em\u003e) is a rare catalase-negative, facultatively anaerobic Gram-positive coccus within the family Aerococcaceae. The species was first described in 1999 from human clinical specimens, and only a small number of clinically relevant human isolates have since been reported[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Most published infections have involved localized suppurative disease, including wound infection, ear abscess, skin abscess, and an infected breast cyst[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRecognition of this organism in routine practice remains limited. Rare catalase-negative Gram-positive cocci are prone to misidentification when laboratories rely only on conventional phenotypic methods[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. MALDI-TOF MS has improved the recognition of unusual clinical isolates, and 16S rRNA gene sequencing remains valuable when uncommon pathogens are recovered from clinically significant specimens[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eScrotal abscess caused by \u003cem\u003eI. ruoffiae\u003c/em\u003e has not, to our knowledge, been reported previously[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. This report describes a 16S rRNA-confirmed scrotal abscess caused by \u003cem\u003eI. ruoffiae\u003c/em\u003e and places the case in the context of the limited published literature.\u003c/p\u003e"},{"header":"2. Case Report","content":"\u003cp\u003eA 63-year-old man was admitted to the Department of Urology on 26 December 2025 with a 2-day history of progressive pain and swelling involving the left scrotum and inguinal region. He denied preceding trauma. His medical history included hypertension, severe traumatic brain injury in September 2024, decompressive craniectomy, and subsequent cranioplasty in August 2025.\u003c/p\u003e \u003cp\u003eAt presentation, physical examination showed a tender erythematous swelling extending from the left scrotum toward the inguinal region. The overlying skin was intact, and fluctuation was equivocal, suggesting either a tense abscess cavity or an inflammatory phlegmon-like stage. The patient was afebrile on admission.\u003c/p\u003e \u003cp\u003eInitial laboratory testing showed a white blood cell count of 9.27 \u0026times; 10^\u003csup\u003e9\u003c/sup\u003e/L and a procalcitonin level of 0.08 ng/mL. These findings did not indicate a marked systemic inflammatory response. Scrotal ultrasonography demonstrated a heterogeneous lesion in the left inguinal-scrotal region measuring approximately 21 \u0026times; 12 \u0026times; 18 mm, with peripheral blood-flow signals. Bilateral epididymal echogenic heterogeneity and left testicular calcification were also reported (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eEmpirical intravenous levofloxacin (0.5 g once daily) was initiated after admission. On hospital day 2, the patient developed a transient fever of 38.0\u0026deg;C, and the lesion ruptured spontaneously with discharge of gray-white purulent material. Needle aspiration drainage was then performed through the rupture site, yielding approximately 5 mL of gray-white pus. Local pain improved after drainage, and the patient became afebrile thereafter.\u003c/p\u003e \u003cp\u003eMicrobiological examination of the aspirated material showed pure growth of small gray-white colonies on sheep blood agar after 48 h of incubation. Gram staining of colony material demonstrated Gram-positive coccoid organisms arranged in pairs and short chains (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). MALDI-TOF MS identified the isolate as \u003cem\u003eI. ruoffiae\u003c/em\u003e using a Bruker Daltonics microflex LT/SH system, with a score of 2.40. Species identification was further confirmed by 16S rRNA gene sequencing using GenBank reference sequence CP096206.2. Detailed microbiological identification and antimicrobial susceptibility testing results are summarized in Tables\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \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\u003eMicrobiological identification of the isolate from the scrotal abscess.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCategory\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMethod\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eResult\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInterpretation / Comment\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDirect smear / colony Gram stain\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGram staining\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGram-positive coccoid organisms\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eArranged in pairs and short chains\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCulture morphology\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSheep blood agar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSmall gray-white colonies\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePure growth after 48 h of incubation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMALDI-TOF MS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBruker Daltonics microflex LT/SH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eScore: 2.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHigh-confidence identification as \u003cem\u003eI. ruoffiae\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e16S rRNA gene sequencing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHefei Anweikang Medical Laboratory\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eI. ruoffiae\u003c/em\u003e (\u0026gt;\u0026thinsp;99% match)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSpecies confirmation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSequence reference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGenBank\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCP096206.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eReference sequence used for confirmation\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecimen source\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePus aspirate from left scrotal lesion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePositive culture\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eClinically significant isolate\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 \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eAntimicrobial susceptibility testing results of the isolate.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\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=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAntimicrobial Class\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAntimicrobial Agent\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMIC\u003c/p\u003e \u003cp\u003e(mg/L)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eZone Diameter\u003c/p\u003e \u003cp\u003e(mm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eInterpretation\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eGuideline / Comment\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBeta-lactams\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePenicillin G\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAmpicillin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAmoxicillin/clavulanate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.12/0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCeftriaxone\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFluoroquinolones\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLevofloxacin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCiprofloxacin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMacrolides\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eErythromycin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLincosamides\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eClindamycin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGlycopeptides\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eVancomycin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOxazolidinones\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLinezolid\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eS*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCLSI M45 / surrogate CLSI M100 criteria\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eNote: Zone diameters from the initial disk diffusion test are provided for the empirically used antibiotics. * Because validated species-specific breakpoints for \u003cem\u003eI. ruoffiae\u003c/em\u003e are unavailable, categorical interpretations were inferred cautiously using surrogate criteria for viridans group streptococci from CLSI M100 where applicable.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eMICs were generated using the VITEK 2 system, and disk diffusion zone diameters were recorded for the empirically used agents. Antimicrobial susceptibility testing was interpreted with reference to CLSI M45; because validated species-specific breakpoints for \u003cem\u003eI. ruoffiae\u003c/em\u003e are unavailable, categorical interpretations were inferred cautiously using surrogate criteria for viridans group streptococci from CLSI M100 where applicable. The isolate showed low MICs for penicillin G, ampicillin, amoxicillin/clavulanate, and ceftriaxone. Levofloxacin also demonstrated in vitro activity.\u003c/p\u003e \u003cp\u003eAlthough the isolate appeared susceptible to levofloxacin in vitro, the bedside course during the pre-drainage phase was unsatisfactory because fever and spontaneous rupture developed before effective source control had been established. On hospital day 5, antimicrobial therapy was changed to intravenous amoxicillin/clavulanate (1.2 g every 8 h). The patient improved steadily after drainage and beta-lactam therapy. By discharge on hospital day 13, the scrotal swelling had resolved, the wound bed showed healthy granulation tissue, and no purulent discharge remained. Oral amoxicillin/clavulanate (875 mg/125 mg, twice daily) was prescribed at discharge.\u003c/p\u003e \u003cp\u003eAt the 1-month and 3-month outpatient follow-up visits, the patient remained asymptomatic, and no clinical evidence of recurrence was observed (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"3. Discussion","content":"\u003cp\u003eThis case broadens the known anatomical spectrum of \u003cem\u003eI. ruoffiae\u003c/em\u003e infection. Published reports have so far involved wound infection, ear abscess, skin abscess, and an infected breast cyst[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Scrotal involvement has not, to our knowledge, been described previously. That distinction matters in practice because unusual site involvement influences whether a rare isolate is dismissed as contamination or recognized as a true pathogen[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eComparison with previous reports helps place the present case in context (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Despite differences in anatomical site, the published cases and the current case share several features: localized purulent disease, the need for careful laboratory identification, and favorable outcomes when active antimicrobial therapy was combined with drainage or other forms of source control when required[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The depth and location of the present lesion, however, made early clinical recognition more challenging than in superficial abscesses. The case also shows that minimal systemic inflammatory abnormalities do not exclude clinically relevant suppuration.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePublished human reports involving Ignavigranum ruoffiae.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStudy\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eClinical Source / Site\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIdentification Method\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eManagement\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMain Relevance\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCollins et al. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWound infection / ear abscess\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhenotypic methods\u0026thinsp;+\u0026thinsp;16S rRNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDescriptive taxonomic report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOriginal species description\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDe Paulis et al. [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSkin abscess\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ePhenotypic methods\u0026thinsp;+\u0026thinsp;16S rRNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDrainage\u0026thinsp;+\u0026thinsp;antimicrobial therapy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eLocalized suppurative infection\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMerlino et al. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSkin abscess\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eClinical microbiology identification\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCase-based management\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSupports pathogenic role in soft tissue abscess\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSuchan et al. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eInfected breast cyst\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eWhole-genome sequencing\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDescriptive microbiological report\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExpands human suppurative spectrum\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePresent case\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eScrotal abscess\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMALDI-TOF MS\u0026thinsp;+\u0026thinsp;16S rRNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eDrainage\u0026thinsp;+\u0026thinsp;beta-lactam therapy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eFirst reported scrotal involvement\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\u003eSeveral practical lessons for clinical recognition and microbiology workflow emerge from this case. First, clinicians should not dismiss the possibility of abscess formation solely because the white blood cell count and procalcitonin level are not markedly elevated[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Second, recovery of an unusual catalase-negative Gram-positive coccus from a clinically significant purulent specimen should prompt full identification rather than dismissal as contamination[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Third, MALDI-TOF MS can provide rapid presumptive identification, while confirmatory sequencing remains useful when rare isolates are recovered from clinically important specimens[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. These steps may reduce the risk of under-recognition of uncommon pathogens in routine microbiology practice.\u003c/p\u003e \u003cp\u003eThe case highlights that in vitro susceptibility may not predict response before drainage. The isolate showed low MICs for beta-lactams and in vitro activity to levofloxacin, yet fever and spontaneous rupture developed during the pre-drainage phase. Several factors could explain that mismatch, including limited drug penetration into an undrained abscess cavity, a high local bacterial burden, the inoculum effect, and altered antimicrobial activity in acidic or protein-rich purulent material[\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The decision to change to amoxicillin/clavulanate after drainage was therefore made as a pragmatic clinical adjustment supported by the susceptibility profile rather than as proof of beta-lactam superiority.\u003c/p\u003e \u003cp\u003eThe route of acquisition remains uncertain. A hypothetical illustration summarizing the possible route of infection and the clinical interpretation of treatment response is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. A history of oral-genital sexual exposure raises the possibility of direct mucocutaneous inoculation. However, the absence of visible skin disruption and the relatively deep inguinoscrotal location of the lesion make a purely superficial inoculation pathway difficult to establish with confidence. An alternative explanation is transient bacteremia with secondary seeding of a site of reduced local resistance[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In this regard, the ultrasonographic findings of left testicular calcification and bilateral epididymal echogenic heterogeneity may suggest pre-existing local abnormalities that could have favored localization. Hematogenous dissemination may therefore be biologically more plausible than direct inoculation in this setting, although neither route can be proven in the absence of blood cultures, paired oral cultures, partner samples, or molecular linkage data[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThis report has limitations. It describes a single patient and cannot establish broad conclusions regarding virulence or optimal therapy. The exact route of infection was not proven. Species identification was strengthened by MALDI-TOF MS and 16S rRNA sequencing, but antimicrobial susceptibility interpretation remained imperfect because species-specific breakpoints are unavailable[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Even so, the case remains informative because it documents a rare pathogen at an unreported anatomical site and illustrates the importance of careful laboratory recognition and source control.\u003c/p\u003e"},{"header":"4. Conclusions","content":"\u003cp\u003eThis case documents, to our knowledge, the first reported scrotal abscess caused by \u003cem\u003eI. ruoffiae\u003c/em\u003e. The report broadens the recognized anatomical spectrum of infection associated with this uncommon organism. Minimal systemic inflammatory abnormalities did not exclude clinically significant localized suppuration. Accurate laboratory identification, cautious interpretation of susceptibility data, and timely source control were central to successful management.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003e\u003cem\u003eI. ruoffiae\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003e\u003cem\u003eIgnavigranum ruoffiae\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003eMALDI-TOF MS\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003ematrix-assisted laser desorption/ionization time-of-flight mass spectrometry\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003e16S rRNA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003e16S ribosomal RNA\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003eMIC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003eminimum inhibitory concentration\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003eAST\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003eantimicrobial susceptibility testing\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003eWBC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003ewhite blood cell count\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003ePCT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003eprocalcitonin\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003eCLSI\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003eClinical and Laboratory Standards Institute\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003eIRB\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003eInstitutional Review Board\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003eNT\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003enot tested\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003e\n \u003cp\u003eVITEK 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\n \u003cp\u003eVITEK 2 automated microbiology system\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 29.3651%;\"\u003eKB\u003c/td\u003e\n \u003ctd style=\"width: 70.6349%;\"\u003e\u003cbr\u003eKirby\u0026ndash;Bauer disk diffusion test\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization, Kaixuan Zhang and Zhikang Wang; methodology, Sudi Zhu; software, Mengyu Zhang; formal analysis, Kaixuan Zhang; data curation, Huihui Li; writing\u0026mdash;original draft preparation, Sudi Zhu; writing\u0026mdash;review and editing, Kaixuan Zhang and Pingping Zhao. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was funded by Science and Technology Bureau of Suzhou City, grant number SZZCXM202522.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInstitutional Review Board Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was conducted in accordance with the Declaration of Helsinki, and approved by the Ethics Committee of Wanbei Coal Electric Group General Hospital (protocol code: 2026-031).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed Consent Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent for publication of the clinical details and accompanying images was obtained from the patient.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are not publicly available due to patient privacy and institutional restrictions. They are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors are grateful to Wanbei Coal Electric Group General Hospital for its support of this work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that there is no conflict of interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eCOLLINS MD, LAWSON PA, MONASTERIO R et al. Ignavigranum ruoffiae sp. nov., isolated from human clinical specimens. Int J Syst Bacteriol 1999; 49 Pt 1: 97\u0026ndash;101.\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1099/00207713-49-1-97\u003c/span\u003e\u003cspan address=\"10.1099/00207713-49-1-97\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDE PAULIS AN BERTONAE, GUTI\u0026eacute;RREZ MA, et al. Ignavigranum ruoffiae, a rare pathogen that caused a skin abscess. JMM Case Rep. 2018;5(2):e005137. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1099/jmmcr.0.005137\u003c/span\u003e\u003cspan address=\"10.1099/jmmcr.0.005137\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMERLINO J, BIRDSALL J, BASKAR SR, et al. Ignavigranum ruoffiae associated with skin abscess. Pathology. 2022;54(1):125\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.pathol.2021.03.009\u003c/span\u003e\u003cspan address=\"10.1016/j.pathol.2021.03.009\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSUCHAN DM, LOOS KD, MACKENZIE KD, et al. A Complete Whole-Genome Sequence of Ignavigranum ruoffiae Strain CPL 242382-20, an Opportunistic Human Pathogen Recovered from a Breast Cyst. Microbiol Resour Announc. 2023;12(1):e0052122. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1128/mra.00521-22\u003c/span\u003e\u003cspan address=\"10.1128/mra.00521-22\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRUOFF KL. Miscellaneous catalase-negative, gram-positive cocci: emerging opportunists. J Clin Microbiol. 2002;40(4):1129\u0026ndash;33. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1128/jcm.40.4.1129-1133.2002\u003c/span\u003e\u003cspan address=\"10.1128/jcm.40.4.1129-1133.2002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFACKLAM R. Identification, classification, and clinical relevance of catalase-negative, gram-positive cocci, excluding the streptococci and enterococci. Clin Microbiol Rev. 1995;8(4):479\u0026ndash;95. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1128/cmr.8.4.479\u003c/span\u003e\u003cspan address=\"10.1128/cmr.8.4.479\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBIZZINI A, JATON K, ROMO D, et al. Matrix-assisted laser desorption ionization-time of flight mass spectrometry as an alternative to 16S rRNA gene sequencing for identification of difficult-to-identify bacterial strains. J Clin Microbiol. 2011;49(2):693\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1128/jcm.01463-10\u003c/span\u003e\u003cspan address=\"10.1128/jcm.01463-10\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLACLAIRE LL, FACKLAM RR. Comparison of three commercial rapid identification systems for the unusual gram-positive cocci Dolosigranulum pigrum, Ignavigranum ruoffiae, and Facklamia species. J Clin Microbiol. 2000;38(6):2037\u0026ndash;42. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1128/jcm.38.6.2037-2042.2000\u003c/span\u003e\u003cspan address=\"10.1128/jcm.38.6.2037-2042.2000\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCHRISTENSEN JJ, DARGIS R, HAMMER M, et al. Matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis of Gram-positive, catalase-negative cocci not belonging to the Streptococcus or Enterococcus genus and benefits of database extension. J Clin Microbiol. 2012;50(5):1787\u0026ndash;91. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1128/jcm.06339-11\u003c/span\u003e\u003cspan address=\"10.1128/jcm.06339-11\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRAMAREDDY RS ALLADIA. Scrotal abscess: Varied etiology, associations, and management. J Indian Assoc Pediatr Surg. 2016;21(4):164\u0026ndash;8. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.4103/0971-9261.186545\u003c/span\u003e\u003cspan address=\"10.4103/0971-9261.186545\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLENHARD ZP JR. Inoculum effect of β-lactam antibiotics. J Antimicrob Chemother. 2019;74(10):2825\u0026ndash;43. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/jac/dkz226\u003c/span\u003e\u003cspan address=\"10.1093/jac/dkz226\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCANCELA COSTA A, GRASS F, ANDRES CANO I, et al. Antibacterial and antifungal drug concentrations in intra-abdominal abscesses: a prospective clinical study. Antimicrob Agents Chemother. 2025;69(1):e0117824. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1128/aac.01178-24\u003c/span\u003e\u003cspan address=\"10.1128/aac.01178-24\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTAN J, TIAN M, ZHAO F, et al. An Investigation of the Male Genitourinary Abscess Originated from Urinary Tract in a Tertiary Hospital, Shanghai, China, from 2004 to 2019. Infect Drug Resist. 2021;14(1):795\u0026ndash;803. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2147/idr.S298250\u003c/span\u003e\u003cspan address=\"10.2147/idr.S298250\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCALDERARO A, MALDI-TOF MS CHEZZIC. A Reliable Tool in the Real Life of the Clinical Microbiology Laboratory. Microorganisms. 2024;12(2). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3390/microorganisms12020322\u003c/span\u003e\u003cspan address=\"10.3390/microorganisms12020322\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMOGLE BT, STEELE JM, THOMAS SJ, et al. Clinical review of delafloxacin: a novel anionic fluoroquinolone. J Antimicrob Chemother. 2018;73(6):1439\u0026ndash;51. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1093/jac/dkx543\u003c/span\u003e\u003cspan address=\"10.1093/jac/dkx543\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-infectious-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"infd","sideBox":"Learn more about [BMC Infectious Diseases](http://bmcinfectdis.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/infd","title":"BMC Infectious Diseases","twitterHandle":"#bmcinfectdis","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Ignavigranum ruoffiae, scrotal abscess, 16S rRNA, MALDI-TOF MS, rare pathogen, source control","lastPublishedDoi":"10.21203/rs.3.rs-9234385/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9234385/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e \u003cem\u003eIgnavigranum ruoffiae\u003c/em\u003e is a rare catalase-negative, facultatively anaerobic Gram-positive coccus. Published human infections remain exceptionally uncommon and have mainly involved localized suppurative disease at non-genitourinary sites. To our knowledge, scrotal involvement has not been reported previously.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCase Report:\u003c/strong\u003eA 63-year-old man presented with a 2-day history of progressive painful swelling of the left scrotum and inguinal region. Systemic inflammatory findings were not striking on admission, with a white blood cell count of 9.27 × 10^9/L and a procalcitonin level of 0.08 ng/mL. Scrotal ultrasonography demonstrated a 21 × 12 × 18 mm heterogeneous lesion in the left inguinal-scrotal region. Empirical intravenous levofloxacin was started after admission. On hospital day 2, the patient developed a transient fever of 38.0 °C, and the lesion ruptured spontaneously. Needle aspiration drainage yielded approximately 5 mL of gray-white pus. Culture showed pure growth of small gray-white colonies on sheep blood agar. Gram staining demonstrated Gram-positive coccoid organisms arranged in pairs and short chains. The isolate was identified as \u003cem\u003eI. ruoffiae\u003c/em\u003e by MALDI-TOF MS using a Bruker microflex LT/SH system (score 2.40) and was further confirmed by 16S rRNA gene sequencing. MICs were generated using the VITEK 2 system. The isolate showed low MICs for beta-lactams and in vitro activity of levofloxacin, although categorical interpretation was made cautiously because species-specific breakpoints are unavailable. On hospital day 5, treatment was changed to intravenous amoxicillin/clavulanate (1.2 g every 8 h). The patient improved steadily thereafter. By discharge on hospital day 13, scrotal swelling had resolved, the wound bed showed healthy granulation tissue, and no purulent discharge remained. Oral amoxicillin/clavulanate was prescribed at discharge. At 1-month and 3-month follow-up, the patient remained asymptomatic, with no clinical evidence of recurrence.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e: This case broadens the known anatomical spectrum of \u003cem\u003eI. ruoffiae\u003c/em\u003e infection by documenting scrotal abscess. The report also shows that localized suppurative infection may occur despite minimal systemic inflammatory response. In vitro susceptibility did not fully predict bedside response before drainage, underscoring the importance of source control and careful microbiological recognition.\u003c/p\u003e","manuscriptTitle":"Scrotal Abscess Caused by Ignavigranum ruoffiae: A Case Report and Literature Review","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-07 10:06:01","doi":"10.21203/rs.3.rs-9234385/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-30T11:21:14+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-15T09:55:40+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"89236914715786558085465668387512869905","date":"2026-04-15T02:58:49+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-14T07:24:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"53717300410580096752405513661529789318","date":"2026-04-01T11:09:58+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-01T06:50:09+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-03-30T02:48:49+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-27T16:28:44+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-27T16:27:52+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Infectious Diseases","date":"2026-03-26T12:50:12+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-infectious-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"infd","sideBox":"Learn more about [BMC Infectious Diseases](http://bmcinfectdis.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/infd","title":"BMC Infectious Diseases","twitterHandle":"#bmcinfectdis","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"cd4859d4-df91-4797-9ae1-2993d7249811","owner":[],"postedDate":"April 7th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-04-30T11:21:14+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-14T11:10:05+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-07 10:06:01","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9234385","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9234385","identity":"rs-9234385","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}