Ignavigranum ruoffiae isolated from a scrotal abscess: a case report and literature review

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 outside the genitourinary tract. Scrotal involvement has not, to our knowledge, been described previously in the available literature. 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. Urinalysis was unremarkable, and urine culture showed no bacterial growth. Scrotal ultrasonography demonstrated a 21 × 12 × 18 mm heterogeneous lesion in the left inguinal-scrotal region, with peripheral strip-like blood-flow signals and no documented internal vascularity. 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 of aspirated pus showed pure growth of small gray-white colonies after 48 h under aerobic conditions with 5% CO2; anaerobic culture recovered no additional anaerobic organisms. The isolate was identified as I. ruoffiae by MALDI-TOF MS using a Bruker microflex LT/SH system with Biotyper software version 4.1.100 and database Revision H2022, which had been locally expanded in the laboratory; the identification score was 2.40. The isolate was further confirmed by 16S rRNA gene sequencing. MICs were generated using the VITEK 2 system with an AST639 card. Quality control was performed using Staphylococcus aureus ATCC 29,213. 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. At 1-month and 3-month follow-up, the patient remained asymptomatic, with no clinical evidence of recurrence. CONCLUSIONS: This case documents the isolation of I. ruoffiae from a scrotal abscess, an anatomical site not previously reported in the available literature. Because the specimen was obtained from a single post-rupture abscess after empirical antimicrobial exposure, the organism should be interpreted as a putative pathogen rather than as definitive proof of sole causation. The case also shows that localized suppurative infection may occur despite minimal systemic inflammatory response. Early clinical evolution before drainage should not be interpreted as definitive antimicrobial failure, and the clinical course emphasizes the importance of source control and careful microbiological recognition.