Colonization-outbreak of two clonally different strains of Serratia marcescens in a neonatal intensive care unit

We describe an outbreak of two clonally different strains of Serratia marcescens in a neonatal intensive care unit. Three colonization cases in the first outbreak phase were related to contact transmission from an index patient during emergency respiratory treatment while eight colonizations in the second phase were caused by contaminated bathing lotion. All transmissions resulted in colonization only and no infections were recorded. Based on our experience and the literature review sufficient staffing levels, basic hygiene and a goal-directed investigation of the environment are the cornerstones of a rapid outbreak termination. The epidemiological search for parallels in cases should be assisted by sophisticated electronic records.