Rapid and sensitive detection of bla(KPC) gene in clinical isolates of Klebsiella pneumoniae by a molecular real-time assay

BACKGROUND: The aim of this study was the rapid identification of bla(KPC) gene in 38 Klebsiella pneumoniae clinical isolates with reduced susceptibility to carbapenems. The modified Hodge Test (MHT) was carried out to phenotypically determine whether resistance to carbapenems was mediated by a carbapenemase. The detection of the bla(KPC) gene was performed by real-time acid nucleic sequence-based amplification (NASBA™™), specifically designed for the detection of KPC RNA target. RESULTS: Thirty-two/38 isolates evaluated by MHT showed the production of carbapenemases, while all the strains exhibited the production of KPC by inhibition test with phenylboronic acid (the combined disk test with IPM/IPM plus phenylboronic acid). The detection of bla(KPC) gene by Nuclisens EasyQ KPC yielded positive results in 38/38 (100%) strains. The presence of bla(KPC) gene was confirmed in all K. pneumoniae isolates when tested by the gold standard PCR assay. CONCLUSIONS: In consideration of the serious challenge represented by infections due to K. pneumoniae it appears necessary the rapid identification of carbapenemases in clinical settings as it is made possible by the use of NASBA™ assay.