Analysis of the mechanisms of fluoroquinolone resistance in urinary tract pathogens

被引:59
作者
Chenia, Hafizah Y.
Pillay, Balakrishna
Pillay, Dorsamy
机构
[1] Durban Univ Technol, Ctr Res Management & Dev, Dept Biotechnol, ZA-4000 Durban, South Africa
[2] Univ KwaZulu Natal, Sch Microbiol & Biochem, Dept Microbiol, ZA-4000 Durban, South Africa
[3] Univ Stellenbosch, Dept Microbiol, ZA-7602 Matieland, South Africa
关键词
fluoroquinolone resistance; OMP; LPS; GyrA and ParC alterations; energy-dependent efflux systems;
D O I
10.1093/jac/dkl404
中图分类号
R51 [传染病];
学科分类号
100401 ;
摘要
Objectives: To characterize the mechanisms of fluoroquinolone resistance in urinary tract pathogens exhibiting a multiple antibiotic resistance phenotype as well as a high-level resistance to fluoroquinolones. Methods: Nineteen Escherichia coli urinary tract infection pathogens exhibiting high-level resistance to fluoroquinolones were characterized in this study. Alterations in outer membrane proteins (OMPs) and lipopolysaccharide (LPS) were analysed by PAGE. Changes to the quinolone resistance-determining regions (QRDRs) of GyrA and ParC were determined by PCR and DNA sequencing. The presence of the qnrA gene was determined by PCR amplification. Ciprofloxacin uptake was determined spectrophotometrically using the quinolone accumulation assay. Results: OMP analysis showed decreased expression, the absence of certain proteins or the presence of proteins with altered molecular weights when compared with wild-type strains. Most isolates possessed a smooth LPS phenotype. Isolates had double mutations in GyrA codons 83 and 87, in addition to a ParC alteration at Ser-80/Glu-84. Isolates accumulated varying levels of ciprofloxacin, and upon the addition of carbonyl cyanide m-chlorophenylhydrazone, increased accumulation was observed in all instances. E. coli isolates with a rough LPS phenotype appeared to accumulate higher levels of ciprofloxacin compared with those with a smooth LPS phenotype expressing OmpF normally, or even those not possessing OmpF. All E. coli isolates tested demonstrated active efflux of ciprofloxacin. Plasmid-mediated quinolone resistance (presence of the qnrA gene) was observed in 36.8% of isolates. Conclusions: A combination of target gene alterations, altered OM permeability, presence of the qnrA gene and active efflux appear to act together to produce a high-level, multiresistance phenotype.
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页码:1274 / 1278
页数:5
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