Frequency of quinolone resistance genes among extended-spectrum β-lactamase (ESBL)-producing Escherichia coli strains isolated from urinary tract infections

Abstract

Background As an opportunistic pathogen, Escherichia coli ( E. coli ) is widely recognized as the main cause of nosocomial infections as well as some disorders especially those associated with urinary tract infections (UTIs). This study, therefore, sets out to determine the extent of antibiotic resistance to quinolones and to measure the frequency of qnr genes (A, B, and S) within extended-spectrum beta-lactamase (ESBL) and non-ESBL-producing strains of E. coli isolated from UTI-diagnosed patients as well as to investigate their antimicrobial susceptibility patterns for some selected antibiotics in southwest Iran. Methods Two hundred E. coli strains were isolated from UTI-diagnosed patients, hospitalized in nine different wards of Ahvaz Golestan Hospital between November 2015 and March 2016. The isolates were confirmed through well-practiced phenotypical methods. Moreover, the antimicrobial susceptibility test was successfully performed using a disk diffusion method. ESBL production among the isolates was screened by double disk synergism test (DDST), and the qnr genes were identified using a multiplex PCR. Results Out of the 200 samples collected, 167 isolates were confirmed to be E. coli strains. Maximum and minimum resistance were reported against nalidixic acid and chloramphenicol with 65.3% and 17.4%, respectively. Most of the isolates were resistant to all three types of quinolones studied in this research. Using multiplex PCR, the qnr genes were found in 100 (59.88%) strains ( qnr A = 10, qnr B = 21, qnr S = 41, qnr B-S = 21, qnr B-A = 1, qnr A-S = 3, qnr A-B-S = 3), 58% of which was found among ESBL-producing isolates. Conclusions Resistance to quinolones antibiotics was highest among ESBL-producing isolates harboring, especially qnr S among other determinants of the qnr gene. There is a need for sensitive antibiotic stewardship especially in hospitals of Ahvaz, Khuzestan province. Further research is needed to ascertain the gravity of quinolones resistance in Iran and to quickly act against its spread among other nosocomial pathogens.

Emerging of Commensal Escherichia Coli Carrying Resistance Genes Against Carbapenems, a Threat to Public Health

“…Probably, communication between pathogenic and commensal bacteria and indirect exposure of commensal ora to antibiotics caused high AMR in the community. As reported by the European Antimicrobial Resistance Surveillance Network (EARS-Net), MDR among infectious E. coli isolates ranged from approximately 1% in 2002 to 4.8% in 2016 and 10.1% in 2018 [37]; however, in our study, MDR was found to be 36%, which is disconcerting. The carriage of commensal AMR, MDR and ESBL-producing isolates in healthy children under three years of age mostly re ects exposure to contamination in the family environment, water, and food rather than increased direct exposure to antimicrobial drugs [38].…”

“…According to a report by Castanheira et al the rates of CR in pathogenic Enterobacteriaceae increased from 0.6% in 1997-2000 to 2.9% in 2013-2016. In our study, the rate of CR in commensal E. coli strains was 1.6%; however, we do not have the exact rate of CR in pathogenic Enterobacteriacea [37].…”

“…Castanheira et al collected pathogenic Enterobacteriaceae isolates from 42 countries over 20 years and found that the rates of MBL-carrying isolates increased from 4.3% of the CR isolates in 2007 to 2009 to 12.7% from 2014 to 2016 [37], while in the present study 66% of commensal CR isolates were detected as MBL-producing. PCR results showed that two and one isolates had the ability to produce NDM and VIM-2, respectively; however, one MBLproducing isolate was negative for all the investigated genes.…”

“…NDM has worldwide distribution and is the most common MBL in the Enterobacteriaceae family [39]. Based on the report by Castanheira et al, the dissemination of isolates carrying bla NDM caused increased CR among Enterobacteriaceae isolates from 2014 to 2016 [37]. For the rst time in Iran, NDM was detected in K. pneumonia in 2013 [40].…”

“…The spread of isolates carrying bla VIM in Italy and Greece led to increased CR among the European countries in 2005 [37]. There are some reports in Iran on the detection of bla VIM−2 in clinical isolates such as hypervirulent Klebsiella pneumonia or pathogenic P. aeruginosa [43,44].…”