Serratia marcescens outbreak in a paediatric oncology unit traced to contaminated chlorhexidine

Over an 18-month period we encountered 12 episodes of Serratia marcescens bacteraemia in 10 patients in a paediatric oncology unit. These were associated with long-term indwelling Hickman intravenous catheters (right atrial) and caused three deaths. Seven of the patients had only mild pyrexial illnesses and made a complete recovery. The source was traced to contaminated aqueous chlorhexidine in a bedside container in which plastic clamps were stored. When this was rectified the outbreak ceased. The identity of the causal Serratia strains was confirmed by plasmid analysis and they showed multiple antibiotic resistance, including the aminoglycosides. The study illustrates the emergence of S. marcescens as an opportunistic pathogen and emphasises the dangers of Hickman-associated bacteraemia.