Quinolone resistance is emerging in Gram-negative pathogens worldwide. In the present study, the prevalence of this problem was determined for different species ofEnterobacteriaceae that were isolated from clinical specimens mainly from Ain Shams University Hospitals at Cairo, Egypt. Escherichia coli had the largest number of isolates, and relatively showed the highest resistance among Enterobacteriaceae but not as compared with other non-enterobacterial species such as Acinetobacter sp. Selected isolates of quinolone resistant Enterobacteriaceae were investigated for qnrA, qnrB and qnrS genes in single reaction by multiplex polymerase chain reaction (PCR). The results showed that 41.2% of the tested isolates were positive for one at least of these genes, which indicates the role of other qnr genes or chromosomal mutations in the process of quinolone resistance. Since, the first reported case of qnrA in Providencia stuartii from clinical Egyptian isolate at 2001, the current study may be the first Egyptian study which reports the detection of qnrA, qnrB and qnrS in E. coli and Klebsiella pneumoniae and qnrA and qnrS in Klebsiella sp and qnrS in Enterobacter sp from clinical specimens. Additionally some isolates harbored more than one of these genes simultaneously. The presence of more than one of the investigated genes in the same isolate did not give a noticeable additional effect on the quinolone resistance.
Key words: qnr, quinolone, multiplex PCR, Enterobacteriaceae, plasmid.
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