The emergence of Serratia marcescens as a pathogen in a newborn unit.

During a 12 month period, the Waikato Hospital Newborn Intensive Care Unit experienced an epidemic of Serratia marcescens infection. Seventeen serious infections occurred, resulting in three deaths. A further 15 cases of minor infection were also noted. Although no point source of introduction was found, gut colonization proved to be the most important reservoir for nosocomial spread of the organism. At the peak of the outbreak, a 95% incidence of rectal colonization with S. marcescens was observed. Eradication was achieved within a 4 month period using cohort isolation of affected infants.