[Investigation of three nosocomial outbreaks of Serratia marcescens in an intensive care unit in Sfax-Tunisia]. / Investigation de trois épidémies d'infections nosocomiales à Serratia marcescens survenues dans le service de réanimation-CHU de Sfax, Tunisie.

UNLABELLED: THE AIM of the study was to type Serratia marcescens responsible for nosocomial outbreaks in an intensive care unit in Sfax -Tunisia. METHODS: The relatedness between S. marcescens isolates was studied by Pulsed field gel electrophoresis (PFGE). We included 56 strains of Serratia marcescens isolated from patients hospitalized in the intensive care unit during 2003 and 2004. Seven epidemiological unrelated strains of Serratia marcescens were also tested. Samples from environment and hands of the nursing and medical staff were collected and cultured to identify the source of contamination. RESULTS: All strains showed a wild type of antimicrobial susceptibility. PFGE typing revealed that three different clones were present. None of the cultures taken from hands of unit staff and from environmental samples yielded positive results for S. marcescens. CONCLUSION: We have confirmed the presence of three consecutive outbreaks caused by three genetically unrelated bacterial clones of Serratia marcescens in the intensive care unit ward. These outbreaks are closely related to the frequent use of colistin and the lack of measures of hygiene in this ward.