Investigation of carbapenem resistance genes by Multiplex PCR in phenotypically determined carbapenem-resistant Klebsiella spp. strains

The increase in carbapenem resistance in Klebsiella spp. strains causes high morbidity and mortality in recent years. Neonatal Intensive Care are suitable environments for the spread of these bacteria. The most important mechanism of resistance to carbapenem in Klebsiella spp. strains is the production of carbapenemase enzymes that inactivate the drug. The genes producing these enzymes are transferrable between bacteria and are responsible for the spread of resistance. The prevalence of genes varies between countries and even between regions. For this reason, it is of great importance to reveal resistance profiles and perform gene analyzes in order to prevent both regional and worldwide spread. In our study, we aimed to investigate carbapenem resistance genes in 50 Klebsiella spp. strains which phenotypically displayed resistance to carbapenem, and isolated from rectal swabs. Klebsiella spp. strains were identified with API20E strips. Minimal Inhibition Concentration (MIC) values of carbapenems were determined by broth microdilution and major five carbapenem genes (OXA-48, NDM, VIM, KPC, IMP) were detected by Multiplex Real Time PCR. Accordingly, among 50 Klebsiella spp., 44 were Klebsiella pneumoniae and 6 were Klebsiella oxytoca. As a consequence, it was found that 49 (98%) of the strains were resistant to ertapenem and imipenem, and 47 (94%) to doripenem and meropenem. As a result of gene analysis, NDM was found in 42% of isolates, OXA-48 was in 16%, NDM + OXA-48 was co-existed in 36% of isolates. Moreover, VIM was detected in one (2%) K. oxytoca strain. KPC and IMP genes were not detected. In conclusion, it was found that NDM is the most prevalent type of carbapenemase and epidemic in Istanbul Medical Faculty Hospital, Pediatrics and Neonatal Intensive Care Service. At the same time, the high prevalence of NDM + OXA-48 is of concern. This indicates that NDM may reach endemic levels in our country.