Journal Article•
Fluoroquinolone-resistance mechanisms and phylogenetic background of clinical Escherichia coli strains isolated in south-east Poland.
TL;DR: Resistance to fluoroquinolones in all of the tested clinical E. coli isolates correlated with point mutations in both gyrA and parC, and plasmid-mediated quinolone resistance (PMRQ) determinants (qnrA or qnrB and/or aac(6')-Ib-cr) were present in 5 out of 20 fluoroquolone-resistant isolates.
Abstract: Fluorochinolones are a class of broad-spectrum antimicrobials in the treatment of several infections, including those caused by Escherichia coli. Due to the increasing resistance of bacteria to antimicrobials, an understanding of fluoroquinolone resistance is important for infection control. The aim of this study was to determine susceptibility of clinical E. coli strains to fluoroquinolones and characterize their mechanisms of quinolone resistance. Totally, 79 non-duplicate clinical E. coli isolates included in this study were mainly from skin lesion -36 (45.6%) isolates; 54 (68.4%) isolates were assigned to phylogenetic B2 group. Resistance to ciprofloxacin was found in 20 isolates. In the quinolone resistance-determining region (QRDR) region of gyrA and parC, 4 types of point mutations were detected. Mutations in parC gene were found in all strains with gyrA mutations. Predominance of double mutation in codon 83 and 87 of gyrA (90%) and in codon 80 of parC (90%) was found. Moreover, plasmid-mediated quinolone resistance (PMRQ) determinants (qnrA or qnrB and/or aac(6')-Ib-cr) were present in 5 (25%) out of 20 fluoroquinolone-resistant isolates. Resistance to fluoroquinolones in all of the tested clinical E. coli isolates correlated with point mutations in both gyrA and parC. The majority of fluoroquinolone-resistant strains belonged to D and B2 phylogenetic groups.
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TL;DR: This study demonstrates for the first time the risk of co-transmission of fluoroquinolone and β-lactam resistance amongst UPEC from Kolkata, posing a major public-health threat and limiting treatment options.
Abstract: Objectives Co-resistance to fluoroquinolones and β-lactams results in treatment complications for uropathogenic Escherichia coli (UPEC) infections. This study aimed to detect the coexistence and co-transmission of plasmid-mediated quinolone resistance (PMQR) and extended-spectrum β-lactamase (ESBL) genes in UPEC from Kolkata, India. Methods Escherichia coli was detected biochemically from culture-positive urine samples. Antimicrobial resistance and ESBL production were confirmed by disk diffusion assay. Transfer of PMQR and ESBL genes was performed using azide-resistant E. coli J53 as recipient. PCR was conducted to identify PMQR and ESBL genes, plasmid incompatibility types, insertion sequences, integrons and ERIC-PCR patterns. Results PMQR determinants were detected in 50.0% (35/70) of ciprofloxacin-resistant isolates, with ESBL production in 42.9% (15/35) and a β-lactamase inhibitor-resistant phenotype in 51.4% (18/35). The highest co-occurrence (37.1%; 13/35) and co-transmission of aac(6′)-Ib-cr with blaTEM, blaCTX-M and blaOXA was observed. Among the conjugal plasmids, replicon types FrepB/FrepB + F1 B were predominant, with rare incidences of A/C, N, X, I1, FIIS, L/M and H1. Distribution of integrons and ISEcp1 and IS26, either alone or in combination, irrespective of PMQR and ESBL gene types was observed. Discrete ERIC-PCR profiles indicated that acquisition of PMQR and ESBLs and their dissemination may be attributed to horizontal gene transfer. Conclusion This study demonstrates for the first time the risk of co-transmission of fluoroquinolone and β-lactam resistance amongst UPEC from Kolkata, posing a major public-health threat and limiting treatment options. Monitoring at the molecular level is necessary to design appropriate prescription policies to combat the alarming rise in drug resistance amongst these uropathogens.
22 citations
TL;DR: It is recognized that the qnrS gene, O25 serotype, and resistance to nalidixic acid had the highest frequencies in UPEC strains isolated from UTI patients.
Abstract: Introduction Urinary tract infection (UTI) is one of the most frequent infections in kidney transplant patients (KTPs). This infection is mainly caused by uropathogenic Escherichia coli (UPEC). Plasmid-mediated quinolone resistance (PMQR) was also increasingly identified in UPEC. This study proposed to investigate the frequency of quinolone-resistance plasmid genes and the O-antigen serogroup among UPEC isolated from KTPs and non-KTP with UTI. Methods Totally, 114 UPEC isolates from 49 KTPs and 65 non-KTPs patients diagnosed with an UPEC-associated UTI were obtained from June 2019 to December 2019 at three laboratory centers in Isfahan, Iran. The isolates were confirmed through phenotypic and genotypic methods. Moreover, the antimicrobial susceptibility test to nalidixic acid, ciprofloxacin, norfloxacin, and ofloxacin was performed using a disk diffusion method. The presence of the qnr gene as well as the serogroup distribution was identified using the PCR method. Result According to data, the distribution of O1, O2, O4, O16, and O25 serogroups were 3.5%, 2.6, 3.5, 3.5, and 20.2%, respectively. Antibiotic susceptibility pattern revealed that the highest and lowest resistance rates were to nalidixic acid (69.3%) and norfloxacin (43.9%), respectively. Also, the frequency of qnrS and qnrB genes were 33.3% and 15.8%, respectively, while none of the isolates was found to be positive for the qnrA gene. There was no significant association between the presence of qnr genes and higher antibiotic resistance. Conclusion This study recognized that the qnrS gene, O25 serotype, and resistance to nalidixic acid had the highest frequencies in UPEC strains isolated from UTI patients.
13 citations
Cites background from "Fluoroquinolone-resistance mechanis..."
...Qnr proteins are protecting target enzymes DNA gyrase and topoisomerase IV of quinolone inhibition [7]....
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...Further, PMQR provides only a low level of quinolone resistance; however, PMQR genes may facilitate the selection of higher-level resistance in the presence of quinolones and lead to treatment breakdown [7]....
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...These groups have been divided into four generations based on their antimicrobial activity; nalidixic acid, ciprofloxacin, and levofloxacin that are members of the first, second, and third generations, respectively [6, 7]....
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TL;DR: The increased use of levofloxacin may contribute to the increased quinolone-resistance of S. pneumoniae and M. catarrhalis, according to the mutant prevention concentration (MPC) determined.
9 citations
Journal Article•
TL;DR: Instrained E. coli strains with positive gene acrA, acrB, acRA,acrA; tolC, mdfA, norE, the presence of efflux pump inhibitor reduced the amount of resistance to antibiotics, suggesting efflux pumps are important in antibiotic resistance.
Abstract: Background: Antibiotic resistance rates in E. coli are rapidly rising, especially with regard to fluoroquinolones. One of the mechanisms that lead to antibiotic resistance is efflux pumps. The aim of this study was phonotypic and genotypic analysis of efflux pump role in fluoroquinolones resistance of E. coli strains isolated from hospitalized patients in Kermanshah 2013. Materials and Methods: In this cross-sectional study, 100 isolates of E. coli were collected from hospitalized patients from Kermanshah. All isolates were identified by standard biochemical tests. The antimicrobial susceptibility patterns were determined by disk diffusion method according to CLSI guidelines. The presence of Efflux pump genes was determined by a PCR method. Results: The rates of resistance to Ceftazidime, Nalidixic Acid, Ciprofloxacin, Norfloxacin, Ofloxacin, Gentamicin, and Tetracycline were 73%, 67%, 55%, 54%, 45%, 38%, and 24%, respectively. According to the results of PCR test, of 100 E. coli isolates, 99% of isolates were positive for acrA, 98% for acrB, 95% for acrE, 98% for acrF, 94% for mdfA, 96% for norE, and 96% for tolC. Conclusion: In Strains with positive gene acrA, acrB, acrA, acrB, tolC, mdfA, norE, the presence of efflux pump inhibitor reduced the amount of resistance to antibiotics. So, efflux pumps are important in antibiotic resistance.
4 citations
References
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TL;DR: To assess the distribution and evolutionary conservation of two distinct prokaryotic repetitive elements, consensus oligonucleotides were used in polymerase chain reaction amplification and slot blot hybridization experiments with genomic DNA from diverse eubacterial species.
Abstract: Dispersed repetitive DNA sequences have been described recently in eubacteria. To assess the distribution and evolutionary conservation of two distinct prokaryotic repetitive elements, consensus oligonucleotides were used in polymerase chain reaction [PCR] amplification and slot blot hybridization experiments with genomic DNA from diverse eubacterial species. Oligonucleotides matching Repetitive Extragenic Palindromic [REP] elements and Enterobacterial Repetitive Intergenic Consensus [ERIC] sequences were synthesized and tested as opposing PCR primers in the amplification of eubacterial genomic DNA. REP and ERIC consensus oligonucleotides produced clearly resolvable bands by agarose gel electrophoresis following PCR amplification. These band patterns provided unambiguous DNA fingerprints of different eubacterial species and strains. Both REP and ERIC probes hybridized preferentially to genomic DNA from Gram-negative enteric bacteria and related species. Widespread distribution of these repetitive DNA elements in the genomes of various microorganisms should enable rapid identification of bacterial species and strains, and be useful for the analysis of prokaryotic genomes.
3,232 citations
"Fluoroquinolone-resistance mechanis..." refers methods in this paper
...Typing of E. coli strains by ERIC-PCR fingerprinting was performed as described by Versalovic et al. (1991)....
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TL;DR: In this paper, a simple and rapid phylogenetic grouping technique based on triplex PCR was proposed, which uses a combination of two genes (chuA and yjaA) and an anonymous DNA fragment, was tested with 230 strains and showed excellent correlation with reference methods.
Abstract: Phylogenetic analysis has shown that Escherichia coli is composed of four main phylogenetic groups (A, B1, B2, and D) and that virulent extra-intestinal strains mainly belong to groups B2 and D. Actually, phylogenetic groups can be determined by multilocus enzyme electrophoresis or ribotyping, both of which are complex, time-consuming techniques. We describe a simple and rapid phylogenetic grouping technique based on triplex PCR. The method, which uses a combination of two genes (chuA and yjaA) and an anonymous DNA fragment, was tested with 230 strains and showed excellent correlation with reference methods.
2,564 citations
TL;DR: These findings provide novel insights into the VFs of extraintestinal pathogenic E. coli and demonstrate the new PCR assay's utility for molecular epidemiological studies.
Abstract: Among 75 urosepsis isolates of Escherichia coli, 29 virulence factor (VF) genes were detected by use of a novel polymerase chain reaction (PCR) assay. Compared with probe hybridization, the PCR assay's specificity was 100% and sensitivity 97.1%. fyuA (yersiniabactin: overall prevalence, 93%), traT (serum resistance, 68%), and a pathogenicity-associated island marker (71%) occurred in most strains from both compromised and noncompromised hosts. Present in <20% of strains each were sfaS, focG (F1C fimbriae), afa/dra, bmaE (M fimbriae), gafD (G fimbriae), cnf1, cdtB (cytolethal distending toxin), cvaC (colicin V), and ibeA (invasion of brain endothelium). Different VFs were variously confined to virulence-associated phylogenetic group B2 (as defined by multilocus enzyme electrophoresis); concentrated in group B2, but with spread beyond; or concentrated outside of group B2. These findings provide novel insights into the VFs of extraintestinal pathogenic E. coli and demonstrate the new PCR assay's utility for molecular epidemiological studies.
1,225 citations
"Fluoroquinolone-resistance mechanis..." refers background in this paper
...Conversely, B2 strains are less resistant than the remaining strains, regardless of the molecular mechanism involved in resistance (Johnson et al., 2002; Johnson and Stell, 2000; Moreno et al., 2006)....
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TL;DR: This review describes the development of the quinolones as antibacterials, the structure and function of gyrase and topoisomerase IV, and the mechanistic basis for quInolone action against their enzyme targets, and suggests approaches to designing new drugs that display improved activity against resistant strains.
Abstract: Quinolones are one of the most commonly prescribed classes of antibacterials in the world and are used to treat a variety of bacterial infections in humans. Because of the wide use (and overuse) of these drugs, the number of quinolone-resistant bacterial strains has been growing steadily since the 1990s. As is the case with other antibacterial agents, the rise in quinolone resistance threatens the clinical utility of this important drug class. Quinolones act by converting their targets, gyrase and topoisomerase IV, into toxic enzymes that fragment the bacterial chromosome. This review describes the development of the quinolones as antibacterials, the structure and function of gyrase and topoisomerase IV, and the mechanistic basis for quinolone action against their enzyme targets. It will then discuss the following three mechanisms that decrease the sensitivity of bacterial cells to quinolones. Target-mediated resistance is the most common and clinically significant form of resistance. It is caused by specific mutations in gyrase and topoisomerase IV that weaken interactions between quinolones and these enzymes. Plasmid-mediated resistance results from extrachromosomal elements that encode proteins that disrupt quinolone–enzyme interactions, alter drug metabolism, or increase quinolone efflux. Chromosome-mediated resistance results from the underexpression of porins or the overexpression of cellular efflux pumps, both of which decrease cellular concentrations of quinolones. Finally, this review will discuss recent advancements in our understanding of how quinolones interact with gyrase and topoisomerase IV and how mutations in these enzymes cause resistance. These last findings suggest approaches to designing new drugs that display improved activity against resistant strains.
839 citations
TL;DR: Aac(6′)-Ib-cr was geographically widespread, stable over time, most common in Escherichia coli, equally prevalent in ciprofloxacin-susceptible and -resistant strains, and not associated with qnr genes.
Abstract: Among 313 Enterobacteriaceae from the United States with a ciprofloxacin MIC of >/=0.25 microg/ml and reduced susceptibility to ceftazidime, aac(6')-Ib was present in 50.5% of isolates, and of these, 28% carried the cr variant responsible for low-level ciprofloxacin resistance. aac(6')-Ib-cr was geographically widespread, stable over time, most common in Escherichia coli, equally prevalent in ciprofloxacin-susceptible and -resistant strains, and not associated with qnr genes.
706 citations
"Fluoroquinolone-resistance mechanis..." refers methods in this paper
...PMQR determinants (qnrA, qnrB, qnrC, qnrD, qnrS and aac(6’)-Ib-cr) were screened for all of 20 fluoroquinolone-resistant isolates by PCR amplification using primers and conditions as described previously (Robicsek et al., 2006; Wang et al., 2009; Cavaco et al., 2009; Park et al., 2006)....
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