BACKGROUND

Fosfomycin is an antibiotic often used to treat urinary tract infections (UTIs) with only rare transient hepatotoxicity. We present a case of fosfomycin-induced liver injury and describe the histopathologic findings on biopsy.

METHODS

A 64-year-old female patient with no prior liver disease or risk factors was started on fosfomycin as prophylaxis for recurrent UTIs. Within a week of her first dose, she presented with fatigue, jaundice, and mixed liver enzyme elevation. Clinical workup for acute liver injury was unremarkable, and biopsy showed panacinar and portal necroinflammation with predominantly lymphocytic infiltrate and cholestasis, with no evidence of cirrhosis. This was thought to be likely related to fosfomycin exposure. Although liver enzymes trended down, bilirubin initially remained elevated. However, within 3 months the patient achieved clinical and biochemical recovery.

RESULTS

Only two other reports of fosfomycin-induced liver injury requiring biopsy were found. Both developed acute cholestatic hepatitis within days of exposure, and subsequent biopsy similarly showed lymphocytic necroinflammation. Although one patient initially developed acute liver failure, both recovered fully within a few months.

CONCLUSION

Overall, these cases suggest potentially an idiosyncratic or immune-mediated liver toxicity of Fosfomycin, which is typically self-limited but may take months to fully resolve. Liver biopsy may be useful in confirming the diagnosis.