Listeria monocytogenes infection in neonates: Investigation of an epidemic.

From March 10 through October 29, 1975, Listeria monocytogenes infection occurred in seven neonates born at a 401-bed general hospital in Greenville, S.C. In the preceding 19 months, there had been only one case. Six of the seven isolates from the infected infants were of serotype JB. Risk of listeriosis in neonates was associated with being born to mothers of low socioeconomic status and being born to mothers who had had vaginitis during pregnancy. Nosocomial transmission of L. monocytogenes appeared unlikely, but the source of the infection is unknown. Of the media used in this study for isolation of L. monocytogenes from mixed cultures, McBride's agar and McBride's agar with nalidixic acid were most useful.