Plasmid-mediated, carbapenem-hydrolysing beta-lactamase, KPC-2, in Klebsiella pneumoniae isolates

Abstract

Four isolates of Klebsiella pneumoniae obtained from patients at a Maryland medical centre exhibited reduced susceptibility to carbapenems and were found to produce the novel, class A, plasmid-mediated, carbapenem-hydrolysing enzyme, KPC-2. This enzyme has 99% identity with the plasmid-mediated, carbapenem-hydrolysing enzyme KPC-1, reported previously in a North Carolina K. pneumoniae isolate. The KPC-2-producing isolates were either susceptible or intermediate to imipenem and meropenem, unlike the KPC-1-producing isolate, which was resistant to these agents. Detection of KPC-2 may be a problem for clinical laboratories because in this study it was associated with positive extended-spectrum beta-lactamase (ESBL) confirmation tests (clavulanate-potentiated activities of ceftriaxone, ceftazidime, cefepime and aztreonam). Therefore, a failure to recognize the significance of reduced carbapenem susceptibility in the isolates that remained susceptible to imipenem or meropenem could have resulted in the isolates being incorrectly identified as ESBL producers.

Carbapenem Resistance in Klebsiella pneumoniae Not Detected by Automated Susceptibility Testing

“…C arbapenem resistance among the Enterobacteriaceae is emerging in the United States, particularly on the East Coast (1)(2)(3)(4)(5)(6). Resistance to the most widely used carbapenems, i.e., imipenem and meropenem, can be mediated by a variety of mechanisms, including β-lactamases, porin changes, and changes in penicillin-binding proteins (1,7,8).…”

Carbapenem-resistant Enterobacteriaceae

“…KPC enzymes were first extracted from K. pneumoniae isolates in many epidemics in the USA, and then they were reported from other gram-negative microorganism all over the world (12,13).…”

Avaliação fenotípica da enzima Klebsiella pneumoniae carbapenemase (KPC) em Enterobacteriaceae de ambiente hospitalar

“…O disco empregado no referido teste é o ertapenem, pois há relatos de que a sensibilidade e a especificidade para KPC são maiores no emprego deste (90% a 100% e 81% a 93%, respectivamente) em relação aos demais carbapenens (7) . É necessário destacar que, na ocasião deste estudo (2008) (14) . Exemplificando, cepa de Klebsiella sp.…”

“…Klebsiella pneumoniae carbapenemase (KPC) é uma enzima produzida por bactérias Gram-negativas (enterobactérias), e sua detecção em isolado bacteriano confere resistência aos antimicrobianos carbapenêmicos, além de inativar penicilinas, cefalosporinas e monobactâmicos (14,15) . É importante salientar que os carbapenens compreendem uma classe amplamente utilizada no tratamento de infecções envolvendo Enterobacteriaceae multirresistente (3) .…”