Abstract
We present the case of a 62-year-old immunocompromised man with ulcerative colitis, primary sclerosing cholangitis, and cirrhosis treated with azathioprine and ustekinumab who quickly developed invasive Listeria monocytogenes infection after incidental identification on routine paracentesis. The infection rapidly progressed from bacterial peritonitis to bacteremia and meningitis within three days. Treatment with ampicillin and trimethoprim/sulfamethoxazole was successful. We highlight the increased risk of invasive listeriosis in immunocompromised individuals, including those on biologic therapies, and the importance of considering Listeria as a pathogen from sterile sites even in asymptomatic patients.