Mutation-based fluoroquinolone resistance in carbapenem-resistant and isolates causing catheter-related bloodstream infections.

Objective: We studied the presence of mutations in the chromosomal quinolone resistance-determining regions (QRDRs) of the fluoroquinolone targets and genes and detected the carbapenem resistance (CR) encoding genes among and isolates from catheter-related bloodstream infections (CRBSIs).

Methods: The study included 39 non-duplicate isolates of (14/39, 35.9%) and (25/39, 64.1%) isolated from 128 confirmed CRBSIs cases. Antimicrobial susceptibility testing was performed, followed by an evaluation of biofilm formation using the tissue culture plate method. The carbapenemase encoding genes were detected by multiplex polymerase chain reaction (PCR). The mutations in QRDRs of and genes were determined by singleplex PCR amplification followed by DNA sequencing and BlastN analysis in the GenBank database. DNA and the translated amino acid sequences were analyzed using the Mega7 bioinformatics tool.

Results: Multidrug-resistant (MDR) and isolates harbored CR encoding genes and combined and genes mutation. The specific substitutions observed in GyrA were Cys173Arg, Cys174Gly, Asp80Val, Tyr178ASP, Tyr84Gly, Glu85Lys, Ser172Leu, and Asp176Asn, while the specific substitutions observed in the ParC amino acid sequence were point mutation 62 Arg, Phe60Leu, Ils66Val, and Gln76Lys. Point mutation 62Arg was detected in two isolates, whereas Ser172Leu mutation was observed in two isolates.

Conclusion: The presence of new single and multiple mutations in QRDR causes the emergence of MDR . and infections in carbapenem-resistant in Egypt, requiring further investigation in Gram-negative bacteria.