Antimicrobial Susceptibility and Molecular Characterization of Carbapenemase-Producing Enterobacter spp. Community Isolates in Belgrade, Serbia

Antimicrobial resistance represents the emerging problem of modern medicine. Despite the fact that Enterobacter spp. is one of the most resistant pathogens, there has been a paucity of data on molecular epidemiology and antimicrobial susceptibility of community isolates in European countries as well as in Serbia. This study was conducted in 2016 and 2017 with the aim to investigate the prevalence of carbapenem-resistant Enterobacter spp. community isolates, molecular determinants of carbapenem resistance, and their genetic relatedness. Seventeen (1.6%) of 1,040 isolates that were positive for carbapenemase screening in accordance with European Committee on Antimicrobial Susceptibility Testing (EUCAST) recommendations were included in the study. Minimum inhibitory concentrations for selected antimicrobials were determined by broth microdilution and by disk diffusion for chloramphenicol. Multiplex polymerase chain reactions (PCRs) for blaKPC, blaNDM, blaIMP, blaVIM, and blaOXA-48-like carbapenemase genes were performed. Clonality was assessed by enterobacterial repetitive intergenic consensus (ERIC)-PCR analysis. All isolates were multidrug resistant. The most frequent carbapenemase gene found was blaNDM (70.6%), followed by isolates coharboring blaNDM and blaOXA-48-like genes (23.5%) and a single isolate with the blaOXA-48-like gene (5.9%). ERIC-PCR molecular typing showed six different clusters (A-F) with clonal relatedness among isolates from the same institution and association of clusters E and F with the blaNDM carbapenemase gene. Our results indicate the need for Enterobacter spp. surveillance both in the community and hospitals to prevent spreading of multiresistant clones.