Catalase-negative listeria monocytogenes causing meningitis in an adult. Clinical and laboratory features.

A 63-year-old previously healthy woman presented with acute meningitis. Cultures of the cerebrospinal fluid yielded a serotype 1/2a isolate of Listeria monocytogenes that was biochemically typical in all respects, other than the reproducible lack of catalase production. During therapy, the patient developed oculomotor dysfunction that was attributed to an abscess in the internal capsule. This case report documents the existence of catalase-negative L. monocytogenes indicating that catalase production should not be a strict criterion for identification of Listeria. Furthermore, this clinical experience extends in vitro and experimental animal studies indicating that catalase production is not a necessary virulence factor for invasion by Listeria.