RESUMO
We investigated the phenotypic and molecular characteristics of Extended-Spectrum-ß-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae clinical isolates from four health-care institutions in Hermosillo, Sonora, Mexico. ESBL-producing isolates were collected from February to August 2016. The prevalence of ESBL-producing E. coli and K. pneumoniae was 11.9 and 8.7%, respectively. High dissemination of resistance to ciprofloxacin (88%), trimethoprim/sulfamethoxazole (72%) and aminoglycosides (59%) were detected, as well as susceptibility to meropenem, amikacin and tigecycline. The ESBL found variants were CTX-M-1 (88%) and CTX-M-9 (5%). The plasmid-mediated quinolone resistance (PMQR) gene aac(6´)-Ib-cr was identified in 62% of a representative sample, whereas the qnrB and qnrS genes were detected in 49% of the isolates. PFGE analyses detected many unrelated clones among the hospital or community isolates. A constant programme of epidemiological surveillance is recommended to understand the dynamics of bacterial resistance to both cephalosporin as well as the fluoroquinolone family of antibiotics.
Assuntos
Escherichia coli/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , beta-Lactamases/biossíntese , Farmacorresistência Bacteriana Múltipla/genética , Farmacorresistência Bacteriana Múltipla/fisiologia , Escherichia coli/isolamento & purificação , Humanos , Klebsiella pneumoniae/isolamento & purificação , México , Testes de Sensibilidade Microbiana , FenótipoRESUMO
The plasmid-mediated quinolone resistance (PMQR) genes have changed the resistance pattern to quinolones, especially among Enterobacteriales. The dissemination of these genes in Latin American countries, where the prescription of fluoroquinolones is high, has been described in several studies; however, no review of the impact of PMQR in this continent has been conducted. This review summarized current knowledge about the circulation of PMQR among Enterobacteriales in Latin American. After the search and selection, 61 articles were included in the study. Most of studies reported PMQR genes among Enterobacteriales from human (47/61, 77%) and animal (18/61, 29.5%) samples, recovered mainly in Brazil (23/61, 37.7%), Mexico (11/61, 18%), and Uruguay (7/61, 11.5%). Nine different PMQR genes (qnrA, qnrB, qnrS, qnrD, qnrE, aac-(6')-Ib-cr, oqxA, oqxB, and qepA) were found in Latin America, with aac (6')-Ib-cr (37/61, 60.6%) and qnrB (26/61, 42.6%) being the most frequently reported. Escherichia coli (40/61, 65.6%) was the species most frequently reported to carry a PMQR gene, followed by Klebsiella pneumoniae (24/61, 39.3%), Enterobacter cloacae (15/61, 24.6%), and Salmonella spp. (14/61, 22.9%). Thus, this review provides important information which might help in designing measures to control the spread of quinolone resistance determinants on this continent.
Assuntos
Farmacorresistência Bacteriana/genética , Enterobacteriaceae/efeitos dos fármacos , Plasmídeos/metabolismo , Quinolonas/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Geografia , Humanos , América LatinaRESUMO
While the description of resistance to quinolones is almost as old as these antimicrobial agents themselves, transferable mechanisms of quinolone resistance (TMQR) remained absent from the scenario for more than 36 years, appearing first as sporadic events and afterward as epidemics. In 1998, the first TMQR was soundly described, that is, QnrA. The presence of QnrA was almost anecdotal for years, but in the middle of the first decade of the 21st century, there was an explosion of TMQR descriptions, which definitively changed the epidemiology of quinolone resistance. Currently, 3 different clinically relevant mechanisms of quinolone resistance are encoded within mobile elements: (i) target protection, which is mediated by 7 different families of Qnr (QnrA, QnrB, QnrC, QnrD, QnrE, QnrS, and QnrVC), which overall account for more than 100 recognized alleles; (ii) antibiotic efflux, which is mediated by 2 main transferable efflux pumps (QepA and OqxAB), which together account for more than 30 alleles, and a series of other efflux pumps (e.g., QacBIII), which at present have been sporadically described; and (iii) antibiotic modification, which is mediated by the enzymes AAC(6')Ib-cr, from which different alleles have been claimed, as well as CrpP, a newly described phosphorylase.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Infecções por Enterobacteriaceae/microbiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Quinolonas/farmacologia , Proteínas de Escherichia coli/genética , HumanosRESUMO
Wastewater treatment plants (WWTPs) harbor bacteria and antimicrobial resistance genes, favoring gene exchange events and resistance dissemination. Here, a culture-based and metagenomic survey of qnrA, qnrB, qnrS, and aac(6')-Ib genes from raw sewage (RS) and activated sludge (AS) of a full-scale municipal WWTP was performed. A total of 96 bacterial isolates were recovered from nalidixic acid-enrichment cultures. Bacteria harboring the aac(6')-Ib gene predominated in RS, whereas qnrS-positive isolates were specific to AS. Novel qnrS- and aac(6')-Ib-cr positive species were identified: Morganella morganii, Providencia rettgeri, and Pseudomonas guangdongensis (qnrS), and Alcaligenes faecalis and P. rettgeri (aac(6')-Ib-cr). Analysis of qnrS and aac(6')-Ib sequences from isolates and clone libraries suggested that the diversity of qnrS is wider than that of aac(6')-Ib. A large number of amino acid mutations were observed in the QnrS and AAC(6')-Ib proteins at previously undetected positions, whose structural implications are not clear. An accumulation of mutations at the C72, Q73, L74, A75 and M76 positions of QnrS, and D181 of AAC(6')-Ib might be important for resistance. These findings add significant information on bacteria harboring qnrS and aac(6')-Ib genes, and the presence of novel mutations that may eventually emerge in clinical isolates.
Assuntos
Escherichia coli/isolamento & purificação , Esgotos , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Fluoroquinolonas , Testes de Sensibilidade Microbiana , Mutação , Plasmídeos/efeitos dos fármacos , QuinolonasRESUMO
A clinical Providencia stuartii isolate SM662 was recovered from a patient hospitalized in the intensive care unit at the Military hospital, Tunisia. This isolate was resistant to penicillins, cephalosporins, aminoglycosides and fluoroquinolones. A marked in vitro synergy between ceftazidime or cefotaxime and amoxicillin-clavulanic acid on Mueller-Hinton agar plates suggested the presence of an extended-spectrum-ß-lactamase. In addition, an unusual synergy was found between cefepime or aztreonam, and cefoxitin or imipenem on a double disk synergy test suggesting a VEB-type extended-spectrum-ß-lactamase. The characterization of ß-lactamases and associated resistance genes was performed by isoelectric focusing, polymerase chain reaction and nucleotide sequencing. Two ß-lactamases bands with pI values of 5.4 and 7.7, which were matched to TEM-1, VEB-1-a and OXA-2-like ß-lactamases were detected. The blaVEB-1-a gene was found to be associated with complex genetic structures, including Re elements. These ß-lactamases were not transferred by electroporation or conjugation experiments to the transconjugants and electroporants. Hybridization methods showed that the extended-spectrum-ß-lactamase encoding gene may have a chromosomal localization. The isolate SM662 produced the quinolone resistance determinants qnrA6 and aac(6')-Ib-cr which were successfully transferred. The detection of an associated chromosomal quinolone resistance revealed the presence of a gyrA mutation at codon 83 (Ser83Ile). This is the first report of the linkage VEB-1-a/OXA-2-like in P. stuartii associated with the description of qnrA6 and aac(6')-Ib-cr genes in this isolate.
Assuntos
Antibacterianos/farmacologia , Providencia/efeitos dos fármacos , Providencia/enzimologia , beta-Lactamases/genética , Farmacorresistência Bacteriana Múltipla , Eletroforese em Gel de Campo Pulsado , Proteínas de Escherichia coli , Humanos , Unidades de Terapia Intensiva , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Providencia/classificação , Providencia/genética , TunísiaRESUMO
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.