[A Case of Necrotizing Fasciitis Caused by Campylobacter fetus subsp. fetus].

Background: Campylobacter fetus subsp. fetus is a Gram-negative spiral-shaped rod commonly colonizing livestock such as cattle and sheep. In humans, it can cause bacteremia, meningitis, and infective endocarditis, particularly in immunocompromised hosts. Herein, we describe a sporadic case of necrotizing fasciitis caused by Campylobacter fetus subsp. fetus. Case presentation: We report a case of necrotizing fasciitis caused by C. fetus subsp. fetus in an older woman in her 80s undergoing maintenance hemodialysis. The patient initially presented with left thigh pain without remarkable findings and was discharged with symptomatic treatment. Three days later, she developed fatigue and was admitted. On hospital day 5, a Gram-negative spiral-shaped bacillus was isolated from blood cultures, and the same organism was subsequently recovered from necrotic fascia tissue of the left thigh, establishing the diagnosis of necrotizing fasciitis caused by C. fetus subsp. fetus. Conclusion: Although early identification was challenging, clinical background, Gram stain findings, and colony morphology facilitated presumptive identification, enabling the timely initiation of appropriate antimicrobial therapy. This case highlights the importance of considering C. fetus subsp. fetus in rare presentations of necrotizing fasciitis.