Molecular Epidemiology, Sequence Types, and Plasmid Analyses of KPC-Producing Klebsiella pneumoniae Strains in Israel

Abstract

ABSTRACT Sporadic isolates of carbapenem-resistant KPC-2-producing Klebsiella pneumoniae were isolated in Tel Aviv Medical Center during 2005 and 2006, parallel to the emergence of the KPC-3-producing K. pneumoniae sequence type 258 (ST 258). We aimed to study the molecular epidemiology of these isolates and to characterize their bla KPC -carrying plasmids and their origin. Ten isolates (8 KPC-2 and 2 KPC-3 producing) were studied. All isolates were extremely drug resistant. They possessed the bla KPC gene and varied in their additional beta-lactamase contents. The KPC-2-producing strains belonged to three different sequence types: ST 340 ( n = 2), ST 277 ( n = 2), and a novel sequence type, ST 376 ( n = 4). Among KPC-3-producing strains, a single isolate (ST 327) different from ST 258 was identified, but both strains carried the same plasmid (pKpQIL). The KPC-2-encoding plasmids varied in size (45 to 95 kb) and differed among each of the STs. Two of the Klebsiella bla KPC-2 -carrying plasmids were identical to plasmids from Escherichia coli , suggesting a common origin of these plasmids. These data indicate that KPC evolution in K. pneumoniae is related to rare events of interspecies spread of bla KPC-2 -carrying plasmids from E. coli followed by limited clonal spread, whereas KPC-3 carriage in this species is related almost strictly to clonal expansion of ST 258 carrying pKpQIL.