ABSTRACT
The present study was conducted to investigate the prevalence of genes encoding resistance to aminoglycosides and fluoroquinolones among twenty-five Pseudomonas aeruginosa isolated between 2002 and 2009. In PCR, following genes were detected: ant(2")-Ia in 9 (36.0%), aac(6')-Ib in 7 (28.0%), qnrB in 5 (20.0%), aph(3")-Ib in 2 (8.0%) of isolates.
Subject(s)
Humans , Aminoglycosides/pharmacology , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Fluoroquinolones/pharmacology , Pseudomonas Infections/microbiology , Pseudomonas aeruginosa/drug effects , Genes, Bacterial , Genotype , Hospitals, University , Microbial Sensitivity Tests , Polymerase Chain Reaction , Prevalence , Poland/epidemiology , Pseudomonas Infections/epidemiology , Pseudomonas aeruginosa/genetics , Pseudomonas aeruginosa/isolation & purificationABSTRACT
Objective To study on plasmid-mediated quinolone-resistant in Escherichia coli strains isolated from fecal samples of chicken and swine from the nine farms around our country.Methods Antimi-crobial susceptibility testing was carried out by broth microdilution testing,gyrA,gyrB,parC,qnr and aac (6')- Ⅰ b-cr were examined by PCR,and the products were sequenced.Conjugation experiment was carried out to proved that the plasmid-mediated quinolone resistance was transferable.Results In the total 818 animal isolates,qnr and aac genes were detected in 38 (4.6%) and 75 (9.2%) strains.The qnrA,qnrB,and qnrS genes were detected in 1 (0.1%),9 (1.1%) and 28 (3.4%) of the isolates.All isolates were negative for qnrC,qnrD genes.Conclusion There is a close relationship between high level quinolone resistance and plasmid-mediated quinolone resistance.The results of the current study highlight food-producing animals as a potential reservoir of antimicrobial-resistant bacteria and clinically important resistance genes.More attention should be paid to the surveillance of such strains.
ABSTRACT
Objective To investigate the importance of plasmid-mediated quinolone resistance in the development of quinolone resistance in clinical isolates of gram-negative bacteria.Methods A total of 541 consecutive clinical isolates of gram-negative ba- cilli resistant or intermediate to ciprofloxacin were screened for the qnrA gene by PCR.Conjugation experiments were carried out with azide-resistant E.coli J53 as a recipient.The aac(6')-Ib-cr gene was detected.The mutations in the quinolone-resist- ance-determining region (QRDR) of the gyrA and parC genes were identified in qnrA positive strains.Results qnrA was identi- fied in 7 of the 541 strains.Among the qnrA positive strains,5 were Enterobacter cloacae.No qnrA was detected in nonfer- menters.Quinolone resistance was transferred in 4 of 7 qnrA positive strains.Transconjugants had 12-to 125-fold increases in MIC of ciprofloxacin relative to that of the recipient.Seven strains contained qnrA with a nucleotide sequence identical to that originally reported.Two transconjugants with higher ciprofloxacin MICs contained aac(6')-Ib-cr gene.Mutations occurred in the QRDR of the gyrA and parC genes in 5 PCR-positive clinical strains.Conclusions Transferable plasmid-mediated quinolone resistance associated with qnrA is highly prevalent in clinical strains of Enterobacter spp.aac(6')-Ib-cr gene and mutations in the quinolone targets may co-exist with qnrA,which may contribute to the further increase of resistance to quinolones.