Scrotal Abscess Caused by Ignavigranum ruoffiae: 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 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.