Detection of Metallo-beta-Lactamase Genes in Clinically Isolated Klebsiella pneumoniae and Klebsiella oxytoca

摘要

We detected and characterized metallo-^lactamase genes {blamp-i and blamp-ii) in third generation cepha-losporin-resistant Klebsiella pneumoniae and Klebsiella oxytoca isolated at Showa University Hospital between January1,2011 and December 31,2012. The cephalosporin一resistant K pneumoniae strains were frequently isolated from the urine, while one strain of if. pneumoniae, which was resistant to carbapenem, was isolated from the stool. We analyzed the phenotypes and genotypes of the metallo-/lactamase genes from the16 strains of cephalosporin-resistant-K pneumoniae and 6 strains of -K. oxytoca isolated from the same ward. The minimum inhibitory concentrations of imipenem were below 4 jug/m in 21out of the 22 isolated strains. The double disc synergy test using ceftazidime and sodium mercaptoacetic acid revealed enlargements in the inhibitory zones of14 of the16 strains oiK pneumoniae and all6 strains of K oxytoca. Metallo，lactamase genes were detected in all of the tested strains, with blamp-i in 3 K pneumoniae and1K. oxytoca, blamp-ii in 13 K pneumoniae and 4 K. oxytoca, and both blamp-i and blaimp-iiin one K oxytoca. Our results indicate that third generation cephalosporin-resistant and imipenem-susceptible K pneumoniae and K. oxytoca possess the metallo-beta-lactamase gene. The active surveillance of metallo-/lactamase genes should be performed in clinical laboratories. [Original]