MOLECULAR EPIDEMIOLOGY OF KLEBSIELLA-PNEUMONIAE STRAINS THAT PRODUCE SHV-4 BETA-LACTAMASE AND WHICH WERE ISOLATED IN 14 FRENCH HOSPITALS

Preliminary results suggested that the diffusion in France of the SW-4 extended-spectrum beta-lactamase was probably due to the spread of on e single epidemic strain of Klebsiella pneumoniae. In this study, we t ested various phenotypic and genotypic markers to compare K. pneumonia e strains producing this enzyme isolated in 14 French hospitals betwee n 1987 and 1989. All of the strains were of the same capsule serotype, K25. Twelve of them were of the same biotype: weak urease activity an d no sucrose fermentation. Among the six plasmid profiles observed, on e accounted for eight strains. Large plasmids of 170 kb encoding SHV-4 beta-lactamase were present in all strains of K. pneumoniae and could be transferred by conjugation with high frequency to Escherichia coli J53-2 or HB101 from all except one strain. Plasmid EcoRI restriction patterns suggested that these plasmids were closely related and simila r to pUD18 encoding SHV-3 beta-lactamase, originally described in Fran ce and differing from SHV-4 by one amino acid substitution. Ribotyping with EcoRI and HindIII and genomic fingerprinting with XbaI by pulsed -held gel electrophoresis were concordant and suggested that 12 of the isolates recovered from the 14 hospitals were probably the same strai n. Dissemination in France of the SHV-4 extended-spectrum beta-lactama se was thus essentially due to the diffusion of a single K. pneumoniae clone.