Listeria moncytogenes cross-contamination in a nursery

Molecular evidence of Listeria monocytogenes cross-contamination in a nursery is presented. Listeria monocytogenes serotype 4b was isolated from the blood and the conjunctiva of a baby with neonatal sepsis who was born after septic amnionitis and premature rupture of membrane. Nine days later, the same bacterium was isolated from the cerebrospinal fluid of a second baby presenting with meningitis. Cervical cultures from the second babyʹs healthy mother were negative for Listeria sp. An in-depth epidemiologic investigation revealed that the same nurse administered routine treatments to both babies to the nursery during a 1-hour interval of time. Pulse-field gel electrophoresis analysis of both strains with 2 different restriction enzymes demonstrated that they were identical and differ from other wild strains of L monocytogenes serotype 4b isolated in Israel. This fact strongly suggests that the second baby was infected during admittance to the nursery as a result of a hospital cross-contamination. (Am J Infect Control 2002;30:322-4.)