Control of a Single Source Nursery Epidemic Due to Serratia Marcescens

Colonization of infants in a newborn nursery was suspected when S. marcescens was grown in cultures from six newborns with urinary tract infection, omphalitis, and balanitis. Umbilical culture of newborns in the nursery revealed S. marcescens in 20 of 31 (64.5%) infants. Extensive culture of personnel and equipment in the delivery room and the general and premature nurseries, however, failed to reveal the organism, with two exceptions. One was the presence of a pure, heavy growth of S. marcescens in 4 of 5 plastic bottles employed to apply saline to umbilical cords and a mixed growth of this and other organisms in suction tubing in the nursery. Within 6 days after removal of the plastic bottles, only 2 of 22 newborns were colonized and no new cases were found after 2 weeks. Almost all those colonized lost the organism within 4 weeks after discharge from the hospital. No familial spread occurred except for colonization of the breast of 2 of 9 nursing mothers. These data are presented as an example of a single source, readily controlled epidemic due to a saprophytic organism associated with disease in a small number of infants. The importance of environmental contamination in nursery epidemics due to gram-negative bacilli, many of which are particularly virulent in the newborn, is discussed.