Patients with naturally occurring, impaired cell-mediated immunity secondary to age and pregnancy are known to be at risk of developing severe and invasive Listeria monocytogenes infections. Immunosuppressant medications, particularly infliximab, are also known to increase this risk.
We present the case of a seven-year-old female on infliximab who was diagnosed with culture positive L. monocytogenes meningitis after a negative cerebral spinal fluid polymerase chain reaction (PCR).
Patients receiving infliximab who display signs of central nervous system infection should be suspected to have L. monocytogenes as an infecting agent, and empiric addition of ampicillin to their antibiotic regimen should be considered, with substitution of trimethoprim-sulfamethoxazole in cases of penicillin allergy, regardless of initial PCR results.