[Use of molecular subtyping methods to investigate two nosocomial outbreaks due to Salmonella Livingstone in Sfax hospital, Tunisia].

OBJECTIVE

The aim of the study was to investigate two nosocomial outbreaks due to Salmonella Livingstone in a pediatric ward in Sfax hospital using molecular typing techniques.

MATERIALS AND METHODS

We included 84 strains of S. Livingstone isolated from patients hospitalized in a pediatric ward between November 1999 through August 2002 in addition to one environmental sample. Three epidemiological unrelated strains of S. Livingstone were also tested. The molecular typing techniques were: plasmid analysis, enterobacterial repetitive intergenic consensus (ERIC-PCR), random amplification of polymorphic DNA (RAPD-PCR) and pulsed field gel electrophoresis (PFGE).

RESULTS

The plasmid analysis and the ERIC-PCR generated a similar profile for outbreak isolates including the environmental sample while the epidemiologically unrelated strains demonstrated distinct patterns. The RAPD-PCR applied on 20 strains showed three patterns but one profile was predominating. All the strains isolate of S. Livingstone, except the veterinary strain, could not be typed by PFGE.

CONCLUSION

Using the molecular typing techniques, we showed that these two outbreaks in the pediatric ward were due to the clonal spread of a single strain of S. Livingstone. The identification of the source of contamination and the improvement of hygiene conditions are required.