Evaluation of molecular epidemiology and phenotypic and genotypic detection of carbapenem resistance mechanisms and effects of liposomal form of meropenem on carbapnem resistant Enterobacteriaceae

Abstract

The present study aimed to assess the prevalence rate of CRE, monitor the antimicrobial susceptibility and phenotypic and genotypic evolution of resistance mechanisms of CRE in Tabriz, Iran. Materials and methods Sixty non-duplicated CRE was recovered from Tabriz hospitals, Iran. Antimicrobial susceptibility testing was performed by the phenotypic methods. The carbapenem resistance mechanisms such as carbapenemase genes, efflux pump hyperexpression and AmpC overproduction were determined by phenotypic and molecular methods. The molecular epidemiological relationship of isolates was done by the Random Amplified Polymorphic DNA (RAPD) method. Also, the antimicrobial efficacy of liposomal meropenem formulation against clinical and laboratory isolates of CRE was done. Results Sixty CRE (50 Klebsiella pneumoniae, six Escherichia coli and four Enterobacter spp.) from urine (52%), wounds (22%), blood (20%) and other body fluids (6%) were isolated from Jan. 2018 to Dec. 2018. According to Carba NP Test, all isolates were positive for carbapenemase, as well as, the Modified-Hodge test detected 57 isolates for carbapenemase activity. AmpC mechanism found in seven isolates (four Enterobacter spp. and three K. pneumoniae). In 10 and 7 isolates of CRE, OmpK35 and OmpK36 were not detected. The presence of carbapenemase was found in all isolates (98%), and the most common gene was blaOXA-48like (70%) and followed by blaNDM, blaIMP, blaVIM and blaKPC in 46%, 18%, 12% and 6 % isolates, respectively. Liposomal meropenem formulation reduced MIC of CRE.