Molecular Epidemiology of Carbapenemresistant Klebsiella pneumoniae Isolates

Abstract

Aim: Carbapenem-resistant Klebsiella pneumoniae infection has become an important clinical problem with reduced therapeutic options. This study aimed to investigate the carbapenem resistancerates and responsible resistance genes in K. pneumoniae isolates derived from clinical samples collected in Istanbul.Materials and Methods: This prospective study included a total of 1452 K. pneumoniae isolates frompatients admitted to our hospital between July 2013 and July 2014. VITEK-2 (bioMérieux, MarcyI’?toile, France) was used for microbial identification and antimicrobial susceptibility testing. Thecarbapenem-resistant isolates identified by VITEK-2 were also found to be resistant to ertapenemby the ertapenem gradient test. Resistance mechanisms of the carbapenem-resistant isolates wereinvestigated using real time-polymerase chain reaction.Results: Of the 1452 K. pneumoniae isolates, 45 (3.1%) were carbapenem-resistant. Of these, 32(71.1%) were blaOXA-48-positive, 9 (20%) blaNDM-positive, and 1 (2.2%) blaVIM-1-positive. None had thegenes blaKPC and blaIMP-1. The greatest susceptibility by the isolated carbapenemase-producing K.pneumoniae was shown to the antimicrobials amikacin and gentamicin.Discussion and Conclusion: In our hospital, there are several mechanisms causing carbapenem resistance, and the blaOXA-48 positivity rate of 71.1% is significant. This resistance may spread rapidly and,through enzymatic resistance gene transfer, lead to hospital epidemics difficult to manage. For thisreason, accurate and rapid laboratory diagnosis is important in infection control. For faster results,molecular methods, as well as phenotypic methods, must be included in the hospital infrastructure.