Investigation of existance of plasmid-mediated (mcr-1, mcr-2) and chromosomal colistin resistance genes (phop/phoq, pmra/pmrb) in members of enterobacteriaceae

The global rise of multi-drug resistance Gram-negative bacteria is an increasing threat to patients. In the last decade, carbapenem-resistant Enterobacteriaceae (CRE) has become one of the most important pathogens in nosocomial infections, especially in intensive care units. CRE poses a problem in the selection of treatment against multiple antibiotic resistance bacteria such as aminoglycosides, fluoroquinolones, cephalosporins and carbapenems. Colistin, which belongs to polymyxins with broad spectrum antimicrobial activities, has been one of the last options antimicrobial agents for the treatment of CRE-mediated infections. The prevalence of colistin-resistant bacteria increased with the use of colistin. Many bacterial pathogens, particularly K. pneumoniae, are structurally resistant to a variety of antibiotics. Until 2015, polymyxin-resistant genes were known to be encoded by chromosomal two-component systems pmrA / pmrB, phoP / phoQ and the negative regulatory mgrB gene. However, in November 2015, the first plasmid-mediated colistin resistance gene mcr-1 was identified. In 2016, the mcr-1 gene was found to be transmitted from animals to humans, and in the following process, the presence and rapid spread of the presence of other mcr genes gave a different dimension to the problem. In the prevention of resistance, it is very important to define the resistance developed against an antibiotic and to know the molecular mechanisms. The aim of this study was to investigate the presence of plasmid-mediated mcr-1 and mcr-2 and chromosomal resistance genes (phoP/phoQ, pmrA/pmrB) in Enterobacteriaceae members. There was no significant increase in expression levels of pmrA, pmrB, phoP and phoQ genes in resistant strains compared to susceptible strains. In addition, mcr-1 gene, which is one of the plasmid-mediated resistance mechanisms, was not detected, whereas mcr-2 gene was detected in 2 K.pneumoniae strains. Key Words: Klebsiella pneumoniae, colistin, mcr-1, mcr-2, pmrA/B, phoP/Q