Investigation of a nosocomial outbreak due to Serratia marcescens in a maternity hospital

OBJECTIVES: To investigate an outbreak of Serratia marcescens in a maternity hospital (November 1994 to May 1995). DESIGN: Retrospective analysis of epidemiological data and prospective study of systematic bacteriological samples from patients and environment, with genotyping of strains by arbitrarily primed polymerase chain reaction. SETTING: A private maternity hospital, Saint-Etienne, France. RESULTS: In the neonatal unit, 1 newborn developed a bacteremia, and 36 were colonized in stools with S marcescens. As the colonization of some newborns was shown to occur only a few hours after delivery, the inquiry was extended to other maternity wards, where 8 babies and 4 mothers were found to be colonized. Environmental sampling led to the isolation of S marcescens from a bottle of enteral feed additive in the neonatal unit and from the transducers of two internal tocographs in the delivery rooms. The genotyping of 27 strains showed two different profiles: a major epidemic profile shared by 22 strains (18 from babies of the neonatal unit, 2 from babies of other units, and 2 from breast milk) and another profile shared by 5 strains (2 from transducers of internal tocographs, 2 from babies, and 1 from a mother). The strain isolated from lipid enteral feeding was not available for typing. Although this source of contamination was removed soon from the neonatal unit, the outbreak stopped only when infection control measures were reinforced in the delivery rooms, including the nonreuse of internal tocographs, CONCLUSIONS: In delivery rooms, the quality of hygiene needs to be as high as in surgery rooms to prevent nosocomial colonization or infection of neonates at birth (Infect Control Hosp Epidemiol 1999;20:233-236).