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High frequency of aac(6')-Ib-cr gene associated with double mutations in gyrA and parC in Escherichia coli isolates from patients with urinary tract infections.

Abstract：

OBJECTIVES:The aims of this study were (i) to determine the frequency of plasmid-mediated resistance to fluoroquinolones (FQs) in Escherichia coli isolated from patients with urinary tract infections (UTIs) of nosocomial and community origin and (ii) to determine the relationships between the presence of extended-spectrum β-lactamases (ESBLs), mutations in the gyrA and parC genes, and resistance to FQs. METHODS:A total of 71 E. coli isolates, including 38 ESBL-producers and 33 non-ESBL-producers, were analysed. The aac(6')-Ib gene was amplified using PCR and was subsequently digested with the BtsCI restriction enzyme to identify aac(6')-Ib-cr, a variant associated with FQ resistance. Detection of qnr genes was performed by multiplex PCR. In isolates that tested positive for these genes, the gyrA and parC genes were sequenced and the modulation factor of an efflux pump inhibitor was determined on the minimum inhibitory concentration (MIC) of norfloxacin. RESULTS:The frequencies of qnrS, qnrB and qnrA were 4.2%, 2.8% and 0%, respectively. The frequency of aac(6')-Ib-cr was 40.8% and this variant was associated with double mutations in gyrA and parC as well as resistance to FQs and ESBL production. Modulation of efflux pump activity was more frequent in resistant isolates that had a wild-type parC gene. CONCLUSION:An interplay of resistance mechanisms increased the level of resistance to FQs, and the high frequency of putative plasmid-mediated quinolone resistance genes associated with ESBL-producing isolates reduced therapeutic options to treat UTIs in the affected population.

journal_name

J Glob Antimicrob Resist

journal_title

Journal of global antimicrobial resistance

authors

Volcão LM,Lacava JP,Gewehr MF,Leal VL,Ramis IB,Ramos DF,Gonçalves CV,Possuelo LG,Minarini LAR,da Silva PEA,von Groll A

doi

10.1016/j.jgar.2017.12.013

subject

Has Abstract

pub_date

2018-06-01 00:00:00

pages

180-183

eissn

2213-7165

issn

2213-7173

pii

S2213-7165(17)30243-6

journal_volume

pub_type

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High frequency of aac(6')-Ib-cr gene associated with double mutations in gyrA and parC in Escherichia coli isolates from patients with urinary tract infections.