Characterization of carbapenemases, ESBLs, and plasmid-mediated quinolone determinants in carbapenem-insensitive Escherichia coli and Klebsiella pneumoniae in Riyadh hospitals.

The main objective of this work was to characterize carbapenemases, extended-spectrum β-lactamases (ESBLs), and plasmid-mediated quinolone resistance (PMQR) among carbapenem-insensitive Klebsiella pneumoniae and Escherichia coli clinical isolates which were isolated from three hospitals in Riyadh. Thirty-one carbapenem-insensitive isolates (21 K. pneumoniae and 10 E. coli) were recovered from March 2014 to May 2014. Susceptibility testing and phenotypic detection tests were used to characterize the classes of β-lactamases. PCR assays were performed for the detection of the genes encoding ESBL (bla, blabla, and bla), carbapenemase (blablabla, bla, bla, and bla), and PMQR (qnrA, qnrB, qnrS, aac(6)-Ib-cr, qepA, oqxA, and oqxB) genes. All carbapenem-insensitive isolates were carbapenemase producers, with 41.9% and 58.1% being class B carbapenemases class D OXA-48, respectively. While the prevalence of ESBL producers was 80.6%. The following resistance genes were detected; OXA-48-like (58.1%), NDM-type (41.9%), CTX-M-1-like (77.4%), CTX-M-9-like (9.6%), TEM-1 (74.2%), OXA-1 (54.8%), SHV-1 (4.4%), qnrS (58.1%), qnrB (3.2%), and aac(6)-Ib-cr (51.6%). The predominant carbapenemases in the isolates that had carbapenem MIC≤4μg/ml and MIC≥12μg/ml were bla and bla respectively. CTX-M-1-like and qnrS were the dominant ESBL and PMQR genes, respectively. This is the first report in which qnrS was described in the isolates from Saudi Arabia.