Molecular Detection of Plasmid-Mediated Quinolone Resistance Genes (qnrA and aac(6?)-Ib-cr) in Drug Resistant Escherichia coli, Sudan

Background: The quinolone group, a synthetic antimicrobial, is widely used worldwide to treat many diseases, including those caused by Gram-negative bacteria. Escherichia coli and others are among the bacteria that produce quinolone resistance genes (qnr) such as qnrA and aac(6?)-Ib-cr. Objective: The present study aimed to the isolate Escherichia coli from patients attending some Hospitals in Wad Medani city, identification of drug resistance patterns and detection of the frequency of quinolones resistance genes; qnrA and aac(6?)-Ib-cr among isolated strains. Methods: A cross-sectional descriptive, hospital-based study included 119 Escherichia coli strains was conducted. A designed questionnaire used for demographic data collection and the attitude toward antimicrobials usage. Clinical specimens were processed for aerobic bacterial isolation and identification. Antimicrobial sensitivity performed by Kirby Bauer disc diffusion technique according to the CLSI guidelines. Presence of qnrA and aac(6?)-Ib-cr genes was assessed by multiplex PCR. Results: Most strains of Escherichia coli originated from urine 53.8% (64/119) and wounds 42.9% (51/119) specimens. Meropenem had the best effect against tested strains with susceptibility of 85% (101/119). Multiplex PCR assay, using specific primers, demonstrated that 41.2% (49/119) and 37.8% (45/119) of isolated Escherichia coli possessed qnrA and aac(6?)-Ib-cr genes respectively. Conclusion: The high rate of qnrA and aac (6)-Ib-cr genes among Escherichia coli necessitate the usage of molecular tools in detecting the genetic determinants of drug resistance microorganisms in countries such as Sudan.

Investigation of plasmid-mediated quinolone resistance in Pseudomonas aeruginosa clinical isolates.

Aims: To investigate plasmid‑mediated quinolone resistance in clinical isolates of Pseudomonas aeruginosa with the polymerase chain reaction (PCR). The plasmid‑mediated quinolone resistance genes have been identified in many bacteria within the Enterobactericeae family, they have not been detected in P. aeruginosa isolates. Subjects and Methods: Identification of the isolates and testing of antibiotic susceptibility was performed in Vitek2 Compact (Biomeriux, France) and Phoinex (BD, USA) automated systems. Screening for the qnrA, qnrB, qnrS, qnrC, aac (6′)‑Ib‑cr and qepA genes was carried out by PCR amplification and aac (6′)‑Ib‑cr DNA sequencing. Results: The qnr and the qepA genes were not detected in any of P. aeruginosa isolates. The aac (6’)‑Ib gene was detected in six of the isolates and positive isolates for aac (6’)‑Ib were sequenced for detection of the aac (6’)‑Ib‑cr variant but aac (6’)‑Ib‑cr was not detected in any isolates. Conclusions: Plasmid‑mediated quinolone resistance genes have so far not been identified in P. aeruginosa isolates. However, qnrB have detected in P. florescens and P. putida isolates. This is the first study conducted on the qnrA, qnrB, qnrS and qnrC genes as well as the qepA and aac (6’)‑Ib‑cr genes in P. aeruginosa clinical isolates.

The first report of the qnrB19, qnrS1 and aac(6´)-Ib-cr genes in urinary isolates of ciprofloxacin-resistant Escherichia coli in Brazil

In this study, we investigated the presence of plasmid-mediated quinolone resistance (PMQR) genes among 101 ciprofloxacin-resistant urinary Escherichia coli isolates and searched for mutations in the quinolone-resistance-determining regions (QRDRs) of the DNA gyrase and topoisomerase IV genes in PMQR-carrying isolates. Eight isolates harboured the qnr and aac(6')-Ib-cr genes (3 qnrS1, 1 qnrB19 and 4 aac(6')-Ib-cr). A mutational analysis of the QRDRs in qnr and aac(6')-Ib-cr-positive isolates revealed mutations in gyrA, parC and parE that might be associated with high levels of resistance to quinolones. No mutation was detected in gyrB. Rare gyrA, parC and parE mutations were detected outside of the QRDRs. This is the first report of qnrB19, qnrS1 and aac(6')-Ib-cr -carrying E. coli isolates in Brazil.

Characteristics of aac(6')-Ib-cr Gene in Extended-Spectrum beta-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Isolated from Chungnam Area / 대한진단검사의학회지

BACKGROUND: Concomitant quinolone resistance in extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae is a crucial problem in the clinical management of infections. In foreign countries, the fluoroquinolone acetylating aminoglycoside-(6)-N-acetyltransferase (aac[6']-Ib-cr) gene, a novel plasmid-mediated quinolone resistance determinant has been reported to occur in conjunction with qnr. We aim to investigate the prevalence and characteristics of concomitant aac(6')-Ib-cr and qnr expression in ESBL-producing Escherichia coli and Klebsiella pneumoniae in Korea. METHODS: Between December 2007 and April 2008, we collected 60 and 69 clonally unrelated non-repetitive clinical isolates of ESBL-producing E. coli and K. pneumoniae, respectively. We studied the expressions of 11 types of ESBL-encoding genes, 4 types of 16s rRNA methylase genes; rmtA, rmtB, rmtC and armA, 3 types of qnr genes; qnrA, qnrB, qnrS and aac(6')-Ib. The presence of aac(6')-Ib-cr variants was detected by sequencing. The involvement of integrons was studied using multiplex PCR and sequencing of gene-cassette arrays. Conjugation experiments were performed to confirm plasmid-mediated resistance and the relationships among coharbored genes. RESULTS: We observed a high prevalence of the cr variant (61.1%) of aac(6')-Ib, and the prevalence of this variant in qnr and aac(6')-Ib-coharboring isolates (67.4%) was higher than in qnr-negative isolates (51.7%). The high prevalence of the cr variant was significantly related to the high minimum inhibitory concentrations (MICs) of ciprofloxacin, tobramycin, and amikacin and indicated the statistically significant roles of qnrB, qnrS, rmtA, and rmtB in quinolone and aminoglycoside resistance. CONCLUSIONS: The aac(6')-Ib-cr variants were widespread and showed significant relation to the high-level quinolone and aminoglycoside resistance in ESBL-producing E. coli and K. pneumoniae.

Dissemination of Plasmid-mediated qnr, aac(6')-Ib-cr, and qepA Genes Among 16S rRNA Methylase Producing Enterobacteriaceae in Korea

Plasmid-mediated quinolone resistance (PMQR) genes: qnr, aac(6')-Ib-cr, and qepA were investigated among 153 armA and 51 rmtB-positive transconjugants and their 204 clinical isolates of Enterobacteriaceae. Overall, qnrB4 and aac(6')-Ib-cr genes were identified in 52.3% (63 K. pneumoniae, 10 E. coli, 4 E. cloacae, and 3 E. aerogenes) and 24.8% (16 K. pneumoniae, 8 E. coli, 6 S. marcescens, 4 E. cloacae, 3 C. freundii and 1 K. oxytoca) of 153 armA-positive isolates, respectively. Four isolates of K. pneumoniae and two isolates of E. coli positive for armA co-harbored both qnrB4 and aac(6')-Ib-cr. The qepA gene was detected in 11.8% (5 E. coli and 1 K. pneumoniae) of 51 rmtB-positive clinical isolates and their transconjugants. Southern hybridization confirmed the co-localization of qepA and rmtB on a large conjugative plasmid of size between 90 to 170 kb. Inc replicon typing showed that qnrB4/6, aac(6')-Ib-cr, and qepA genes were principally disseminated by IncFIIAs, IncL/M, and IncF plasmids, respectively. This study constitutes the first report of the three known PMQR genes among the 16S rRNA methylase producing Enterobacteriaceae isolates of human origin from Korea.