Patterns of Fluoroquinolone Resistance in Enterobacteriaceae Isolated from the Assiut University Hospitals, Egypt: A Comparative Study.

An increasing pattern of fluoroquinolone resistance (FQR) among bacterial pathogens has been described worldwide. In this study, we compared the patterns of genetic mechanisms that confer FQR for and isolated from the Assiut University Hospitals in Egypt. Eighty-seven clinical and isolates were tested for mutations in , , , and genes by polymerase chain reaction (PCR) amplification and DNA sequencing. The presence of plasmid-mediated quinolone resistance (PMQR) genes , , , , was screened by PCR and characterized by conjugation. Correlations between different FQR mechanisms and ciprofloxacin minimal inhibitory concentration (MIC) levels were determined. A higher number of quinolone resistance-determining region (QRDR) mutations was detected in , while the number of PMQR determinants was significantly higher in . However, showed stronger correlations than between MIC levels and number of mutations in the QRDR per isolate ( = 0.8,  < 0.0001 and  = 0.7,  < 0.0001, respectively) as well as between MIC levels and number of plasmids ( = 0.4,  = 0.005 and  = 0.3,  = 0.02, respectively). Although we observed a prevalence of chromosomal mutations for and the presence of plasmid-encoded genes for that resulted in FQR phenotype, high levels of FQR appeared to occur as a result of gradual accumulation of mutations in QRDR for both bacteria. To our best of knowledge, this is the first study to report and compare the correlation between FQ MIC levels and different genetic mechanisms for FQR in Enterobacteriaceae.