CLONAL OUTBREAKS OF EXTENDED-SPECTRUM BETA-LACTAMASE-PRODUCING STRAINS OF KLEBSIELLA-PNEUMONIAE DEMONSTRATED BY ANTIBIOTIC SUSCEPTIBILITY TESTING, BETA-LACTAMASE TYPING, AND MULTILOCUS ENZYME ELECTROPHORESIS

Nineteen extended-spectrum beta-lactamase (ESBla)-producing Klebsiella pneumoniae isolates from Rouen Hospital were investigated for their implication in nosocomial outbreaks: in addition to antibiotic susceptibility testing, the ESBlas were characterized by isoelectric focusing, and the genetic relationships between the strains were analyzed by multilocus enzyme electrophoresis using a combined polyacrylamide electrophoresis electrophoretic transfer technique. Four isoelectric focusing beta-lactamase patterns and 11 enzyme electrophoretic types (ETs) among the strains tested were described. Three strains isolated in the same neurological unit over a 7-day period exhibited an SHV 3 beta-lactamase (pI 7.0) and were assigned to a common ET. Three of five strains isolated from patients in a rehabilitation center over a 6-week period harbored an SW 4 beta-lactamase (pI 7.8) and exhibited the same ET. These results differentiate nosocomial transmission from sporadic cases and provide evidence that multilocus enzyme electrophoresis is a potential tool for studying genetic relationships between strains harboring a common ESBla.