Rapid detection of Klebsiella pneumoniae carbapenemase genes in enterobacteriaceae directly from blood culture bottles by real-time PCR

Abstract

Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacteriaceae are endemic in New York City hospitals and have been associated with serious infections globally. A real-time polymerase chain reaction (RT-PCR) assay was developed to detect carbapenem resistance attributable to KPC from blood culture bottles positive for gram-negative bacilli. Culture confirmation of carbapenemase production included automated imipenem and meropenem susceptibility testing and ertapenem susceptibility testing by disk-diffusion. A total of 323 Enterobacteriaceae isolates were tested, of which 8.7% (n = 28) demonstrated carbapenem-resistance by automated and manual susceptibility testing methods or by RT-PCR. The sensitivity, specificity, and positive and negative predictive values of the RT-PCR assay when compared with the automated method were 92.9%, 99.3%, 92.9%, and 99.3%, respectively, and 96.4%, 99.7%, 96.4%, and 99.7%, respectively, when compared with the ertapenem disk-diffusion method. RT-PCR is a rapid and reliable means of detecting carbapenem resistance due to KPC-plasmids in Enterobacteriaceae directly from blood culture bottles.