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Pluralibacter gergoviae is a member of the Enterobacteriaceae family that has been reported sporadically. Although P. gergoviae strains exhibiting multidrug-resistant profiles have been identified an in-depth genomic analysis focusing on antimicrobial resistance (AMR) has been lacking, and was therefore performed in this study. Forty-eight P. gergoviae strains, isolated from humans, animals, foods, and the environment during 1970-2023, were analyzed. A large number of single-nucleotide polymorphisms were found, indicating a highly diverse population. Whilst P. gergoviae strains were found to be circulating at the One Health interface, only human and environmental strains exhibited multidrug resistance genotypes. Sixty-one different antimicrobial resistance genes (ARGs) were identified, highlighting genes encoding mobile colistin resistance, carbapenemases, and extended-spectrum ß-lactamases. Worryingly, the co-occurrence of mcr-9.1, blaKPC-2, blaCTX-M-9, and blaSHV-12, as well as mcr-10.1, blaNDM-5, and blaSHV-7, was detected. Plasmid sequences were identified as carrying clinically important ARGs, evidencing IncX3 plasmids harboring blaKPC-2, blaNDM-5, or blaSHV-12 genes. Virulence genotyping underlined P. gergoviae as being a low-virulence species. In this regard, P. gergoviae is emerging as a new multidrug-resistant species belonging to the Enterobacteriaceae family. Therefore, continuous epidemiological genomic surveillance of P. gergoviae is required.
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OBJECTIVES: This study aimed to evaluate the persistence of the plasmid-mediated quinolone resistance (PMQR) among uropathogenic Escherichia coli strains grown under or without exposure to subinhibitory concentrations of ciprofloxacin. Based on that, we evaluated the possible spontaneous loss or maintenance of PMQR and the possible appearance of compensatory mutations in gyrA and parC genes. METHODS: Three uropathogenic E. coli strains harbouring chromosomal mutations in the gyrA and/or parC genes coupled with qnrS1 or qnrB2 determinants carried by distinct plasmid sizes and incompatibility N groups (IncN/ST1, IncN/ST5) were evaluated using in vitro and in vivo assays. RESULTS: PMQRs remained stable in all strains throughout the generations evaluated, independently of exposure to ciprofloxacin in both in vivo and in vitro assays. Analysis of gyrA and parC genes after in vivo and in vitro assays revealed that no changes occurred in quinolone-resistance determining regions (QRDR). CONCLUSION: We demonstrated that IncN plasmids were persistent over 14 days in E. coli clinical strains independently of exposure to ciprofloxacin, as well as previous mutations in QRDR.
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Proteínas de Escherichia coli , Escherichia coli Uropatogênica , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Proteínas de Escherichia coli/genética , Testes de Sensibilidade Microbiana , Plasmídeos/genética , Escherichia coli Uropatogênica/genéticaRESUMO
[This corrects the article DOI: 10.3389/fmicb.2019.02503.].
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Antimicrobial resistance is an increasing problem worldwide, and Salmonella spp. resistance to quinolone was classified by WHO in the high priority list. Recent studies in Europe and in the US reported the presence of small plasmids carrying quinolone resistance in Enterobacteriaceae isolated from poultry and poultry products. The aims of this study were to identify and characterize plasmid-mediated quinolone resistance in Salmonella spp. and to investigate transduction as a possible mechanism associated to its dissemination. First, we assessed resistance to nalidixic acid and/or ciprofloxacin in 64 Salmonella spp. and detected resistance in eight of them. Genomic analyses determined that six isolates of different serotypes and sources carried an identical 2.7-kb plasmid containing the gene qnrB19 which confers quinolone resistance. The plasmid detected also has high identity with plasmids reported in the US, Europe, and South America. The presence of similar plasmids was later surveyed by PCR in a local Salmonella collection (n = 113) obtained from diverse sources: food (eggs), wild and domestic animals (pigs, horse, chicken), and human clinical cases. qnrB19-carrying plasmids were found in 8/113 Salmonella tested strains. A bioinformatics analysis including Chilean and previously described plasmids revealed over 95.0% of nucleotide identity among all the sequences obtained in this study. Furthermore, we found that a qnrB19-carrying plasmid can be transferred between Salmonella of different serotypes through a P22-mediated transduction. Altogether our results demonstrate that plasmid-mediated quinolone resistance (PMQR) is widespread in Salmonella enterica of different serotypes isolated from human clinical samples, wild and domestic animals, and food in Chile and suggest that transduction could be a plausible mechanism for its dissemination. The occurrence of these antimicrobial resistance elements in Salmonella in a widespread area is of public health and food safety concern, and it indicates the need for increased surveillance for the presence of these plasmids in Salmonella strains and to assess their actual impact in the rise and spread of quinolone resistance.
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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.
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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
This study aimed to investigate the antimicrobial resistance profile to quinolones, the presence of quinolone-resistant determinants and the plasmid replicon typing in environmental Achromobacter sp. isolated from Brazil. Soil and water samples were used for bacterial isolation. The antimicrobial susceptibility testing was performed by minimum inhibitory concentration method. The detection of mutations in the quinolone resistance-determining regions (QRDR) genes, the presence of plasmid-mediated quinolone resistance (PMQR) genes, and plasmid replicons were performed by PCR. A total of 16 isolates was obtained from different cultures, cities, and states of Brazil. All isolates were non-susceptible to ciprofloxacin, norfloxacin, and levofloxacin. Some mutations in QRDR genes were found, including Gln-83-Leu and Asp-87-Asn in the gyrA and Gln-80-Ile and Asp-84-Ala in the parC. Different PMQR genes were detected, such as qnrA, qnrB, qnrS, oqxA, and oqxB. Three different plasmid families were detected, being most presented the ColE-like, followed by IncFIB and IncA/C. The presence of different PMQR genes and plasmids in the isolates of the present study shows that environmental bacteria can act as reservoir of important genes of resistance to fluoroquinolones, which is of great concern, due to the potential of horizontal dissemination of these genes. Besides that, there are no studies reporting these results in Achromobacter sp. isolates.
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Achromobacter/genética , Antibacterianos/farmacologia , Técnicas de Tipagem Bacteriana/métodos , Farmacorresistência Bacteriana/genética , Plasmídeos/química , Replicon , Achromobacter/efeitos dos fármacos , Achromobacter/crescimento & desenvolvimento , Achromobacter/metabolismo , Sequência de Aminoácidos , Brasil , Ciprofloxacina/farmacologia , DNA Girase/genética , DNA Girase/metabolismo , DNA Topoisomerase IV/genética , DNA Topoisomerase IV/metabolismo , Expressão Gênica , Humanos , Levofloxacino/farmacologia , Testes de Sensibilidade Microbiana , Mutação , Norfloxacino/farmacologia , Plasmídeos/metabolismo , Microbiologia do Solo , Microbiologia da ÁguaRESUMO
BACKGROUND: Uropathogenic Escherichia coli (UPEC) are one of the main bacteria causing urinary tract infections (UTIs). The rates of UPEC with high resistance towards antibiotics and multidrug-resistant bacteria have increased dramatically in recent years and could difficult the treatment. METHODS: The aim of the study was to determine multidrug-resistant bacteria, antibiotic resistance profile, virulence traits, and genetic background of 110 E. coli isolated from community (79 isolates) and hospital-acquired (31 isolates) urinary tract infections. The plasmid-mediated quinolone resistance genes presence was also investigated. A subset of 18 isolates with a quinolone-resistance phenotype was examined for common virulence genes encoded in diarrheagenic and extra-intestinal pathogenic E. coli by a specific E. coli microarray. RESULTS: Female children were the group most affected by UTIs, which were mainly community-acquired. Resistance to trimethoprim-sulfamethoxazole, ampicillin, and ampicillin-sulbactam was most prevalent. A frequent occurrence of resistance toward ciprofloxacin (47.3%), levofloxacin (43.6%) and cephalosporins (27.6%) was observed. In addition, 63% of the strains were multidrug-resistant (MDR). Almost all the fluoroquinolone (FQ)-resistant strains showed MDR-phenotype. Isolates from male patients were associated to FQ-resistant and MDR-phenotype. Moreover, hospital-acquired infections were correlated to third generation cephalosporin and nitrofurantoin resistance and the presence of kpsMTII gene. Overall, fimH (71.8%) and fyuA (68.2%), had the highest prevalence as virulence genes among isolates. However, the profile of virulence genes displayed a great diversity, which included the presence of genes related to diarrheagenic E. coli. Out of 110 isolates, 25 isolates (22.7%) were positive to qnrA, 23 (20.9%) to qnrB, 7 (6.4%) to qnrS1, 7 (6.4%) to aac(6')lb-cr, 5 (4.5%) to qnrD, and 1 (0.9%) to qnrC genes. A total of 12.7% of the isolates harbored blaCTX-M genes, with blaCTX-M-15 being the most prevalent. CONCLUSIONS: Urinary tract infection due to E. coli may be difficult to treat empirically due to high resistance to commonly used antibiotics. Continuous surveillance of multidrug resistant organisms and patterns of drug resistance are needed in order to prevent treatment failure and reduce selective pressure. These findings may help choosing more suitable treatments of UTI patients in this region of Mexico.
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Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Infecções por Escherichia coli/patologia , Infecções Urinárias/tratamento farmacológico , Infecções Urinárias/microbiologia , Escherichia coli Uropatogênica/genética , Escherichia coli Uropatogênica/patogenicidade , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/uso terapêutico , Criança , Pré-Escolar , Estudos Transversais , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , México , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Infecções Urinárias/epidemiologia , Escherichia coli Uropatogênica/efeitos dos fármacos , Adulto JovemRESUMO
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 ß-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.
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DNA Girase/genética , DNA Topoisomerase IV/genética , Farmacorresistência Bacteriana Múltipla/genética , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Infecções Urinárias/microbiologia , Antibacterianos/farmacologia , Brasil , Escherichia coli/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Mutação , Reação em Cadeia da PolimeraseRESUMO
Plasmid-mediated quinolone resistance (PMQR) determinants combined with mutations in quinolone resistance-determining regions (QRDRs) and clonal dissemination were investigated in 40 fluoroquinolone-resistant Klebsiella pneumoniae and Escherichia coli isolates from nosocomial and community-acquired infections. We observed nucleotide substitutions in gyrA (Ser83Ile, Val37Leu, Lys154Arg, Ser171Ala, Ser19Asn, Ile198Val, Ser83Tyr, Ser83Leu, Asp87Asn and Asp87Gly) and parC genes (Ser80Ile, Glu84Lys, Ala129Ser, Val141Ala and Glu84Gly). Two novel substitutions were detected in the gyrA gene (Val37Leu and Ile198Val). The presence of PMQR genes predominated in community isolates (55.5â%). In addition to the frequent presence of the class 1 integron in isolates from community-acquired infections, the genetic similarity results obtained by PFGE showed high genomic diversity. This study suggests that management of multidrug-resistant Enterobacteriaceae isolates from the community are a possible source of genetic mobile elements that carry genes that confer resistance to fluoroquinolones. More attention should be paid to the surveillance of community-acquired infections.
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OBJECTIVES: This study aimed to describe the characteristics of clinical isolates of extended-spectrum ß-lactamase (ESBL)-producing enterobacteria (EPE) in Uruguay's paediatric hospital. METHODS: ESBLs, qnr alleles and aac(6')-Ib-cr were sought and characterised in EPE isolated between March 2010 and March 2012. Transfer of resistance determinants was assessed by conjugation. Incompatibility (Inc) groups, plasmid toxin-antitoxin systems (TAS) and plasmid size were determined in transconjugants. Clonality was analysed by pulsed-field gel electrophoresis. Multilocus sequence typing was done for ESBL-producing Klebsiella pneumoniae. RESULTS: A total of 77 EPE isolates were characterised, comprising 43% K. pneumoniae, 19.5% Serratia marcescens, 19.5% Escherichia coli, 17% Enterobacter cloacae and 1% Klebsiella oxytoca. ESBLs belonged mainly to the blaCTX-M family (69.6%) [blaCTX-M-15 (45%) and blaCTX-M-2 (31%)]. The aac(6')-Ib-cr/qnrB duplex was the most frequently detected plasmid-mediated quinolone resistance mechanism; this association was detected in K. pneumoniae harbouring blaCTX-M-15. Transconjugants were obtained for 71% of the EPE. Amongst transconjugants, certain combinations were found between ESBLs and Inc group, e.g. IncA/C-blaCTX-M-2, IncHI1/HI2-blaCTX-M-9 and IncHI1/HI2-blaSHV-12. In addition, the combination ccdAB-blaCTX-M-15 was also found. K. pneumoniae isolates harbouring blaCTX-M-15/aac(6')-Ib-cr/qnrB showed allodemic behaviour, with a predominance of ST14, ST45 and ST48. CONCLUSIONS: In this study, epidemiological changes in ESBL distribution could be explained by the spread of K. pneumoniae harbouring blaCTX-M-15/aac(6')-Ib-cr/qnrB, encoded mainly on conjugative plasmids featuring ccdAB TAS. Since reports of TAS in K. pneumoniae plasmids are scarce, new strategies are needed to combat intrinsic selection pressure exerted by the association, in conjugative plasmids, of resistance mechanisms with TAS.
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Acetiltransferases/genética , Proteínas de Bactérias/genética , Transferência Genética Horizontal , Infecções por Klebsiella/epidemiologia , Klebsiella pneumoniae/genética , Plasmídeos/classificação , beta-Lactamases/genética , Conjugação Genética , Hospitais Pediátricos , Humanos , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/classificação , Klebsiella pneumoniae/isolamento & purificação , Tipagem de Sequências Multilocus , Sistemas Toxina-Antitoxina/genética , Uruguai/epidemiologiaRESUMO
Salmonella spp. is an important zoonotic pathogen related to foodborne diseases. Despite that quinolones/fluoroquinolones are considered a relevant therapeutic strategy against resistant isolates, the increase in antimicrobial resistance is an additional difficulty in controlling bacterial infections caused by Salmonella spp. Thus, the acquisition of resistance to quinolones in Salmonella spp. is worrisome to the scientific community along with the possibility of transmission of resistance through plasmids. This study investigated the prevalence of plasmid-mediated quinolone resistance (PMQR) in Salmonella spp. and its association with fluoroquinolone susceptibility in Brazil. We evaluated 129 isolates, 39 originated from food of animal sources, and 14 from environmental samples and including 9 from animals and 67 from humans, which were referred to the National Reference Laboratory of Enteric Diseases (NRLEB/IOC/RJ) between 2009 and 2013. These samples showed a profile of resistance for the tested quinolones/fluoroquinolones. A total of 33 serotypes were identified; S. Typhimurium (63) was the most prevalent followed by S. Enteritidis (25). The disk diffusion test showed 48.8% resistance to enrofloxacin, 42.6% to ciprofloxacin, 39.53% to ofloxacin, and 30.2% to levofloxacin. According to the broth microdilution test, the resistance percentages were: 96.1% to nalidixic acid, 64.3% to enrofloxacin, 56.6% to ciprofloxacin, 34.1% to ofloxacin, and 30.2% to levofloxacin. Qnr genes were found in 15 isolates (8 qnrS, 6 qnrB, and 1 qnrD), and the aac(6')-Ib gene in 23. The integron gene was detected in 67 isolates with the variable region between ±600 and 1000 bp. The increased detection of PMQR in Salmonella spp. is a serious problem in Public Health and must constantly be monitored. Pulsed-field gel electrophoresis was performed to evaluated clonal profile among the most prevalent serovars resistant to different classes of quinolones. A total of 33 pulsotypes of S. Typhimurium were identified with a low percentage of genetic similarity (≤65%). This result demonstrates the presence of high diversity in the resistant clones evaluated in this study.
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Abstract: INTRODUCTION: Plasmid-mediated quinolone resistance (PMQR) is a growing clinical concern worldwide. The main aims of this study were to detect qnr-encoding genes and to evaluate the clonal relatedness of qnr-positive Enterobacter cloacae isolates. METHODS: A total of 116 E. cloacae isolates that were not susceptible to quinolone were obtained from seven hospitals in Tehran, five hospitals in Qazvin, and two hospitals in Karaj (Iran). Bacterial identification was performed using standard laboratory methods and API 20E strips. Quinolone resistance was determined using the Kirby-Bauer disk diffusion method according to the Clinical Laboratory Standards Institute (CLSI) guidelines. PCR and sequencing were employed to detect qnrA, qnrB, and qnrS genes, and clonal relatedness was assessed using the enterobacterial repetitive intergenic consensus (ERIC)-PCR method. RESULTS: In total, 45 (38.8%) and 71 (61.2%) of isolates showed high- and low-level quinolone resistance, respectively, and qnr-encoding genes were detected in 70 (60.3%) of them. qnrB1 [45 (38.8%) isolates] was the most commonly detected gene, followed by qnrS1 [28 (24.1%) isolates] and qnrB4 [18 (15.5%) isolates] either alone or in combination with other genes. The results of the ERIC-PCR revealed that 53 (75.7%) qnr-positive isolates were genetically unrelated. CONCLUSIONS: This study describes, for the first time, the high prevalence of the qnrB1, qnrS1, and qnrB4 genes among E. cloacae isolates in Iran. The detection of qnr genes emphasizes the need for establishing tactful policies associated with infection control measures in hospital settings in Iran.
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Humanos , Masculino , Feminino , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Adulto Jovem , Enterobacter cloacae/efeitos dos fármacos , Quinolonas/farmacologia , Farmacorresistência Bacteriana , Infecções por Enterobacteriaceae/microbiologia , Antibacterianos/farmacologia , Plasmídeos/genética , Testes de Sensibilidade Microbiana , Prevalência , Estudos Transversais , Enterobacter cloacae/genética , Irã (Geográfico) , Pessoa de Meia-IdadeAssuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla , Infecções por Escherichia coli/veterinária , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Genes Bacterianos , Doenças dos Cavalos/microbiologia , Animais , Brasil , DNA Bacteriano/química , DNA Bacteriano/genética , Escherichia coli/enzimologia , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Cavalos , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Análise de Sequência de DNARESUMO
Here we report the detection of a Leclercia adecarboxylata strain, isolated from a case of osteomyelitis, harbouring multiple antibiotic resistance genes encoded on a 450-kb IncHI1/HI2 conjugative plasmid (pLa12). The plasmid carried a complex class 1 integron with the genetic array intI1-aac(6')-Ib-cr-blaOXA-1-catB3-arr3-qacEΔ1-sul1-ISCR1; in addition, a blaDHA-1-like allele linked to ampR-qacEΔ1-sul1 as well as blaSHV-12, blaTEM-1 and qnrB4-like genes were found. To the best of our knowledge, this is the first report of L. adecarboxylata harbouring transferable resistance genes to quinolones, chloramphenicol and rifampicin as well as a plasmidic class C ß-lactamase.
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To analyse the occurrence and prevalence of plasmid-mediated quinolone resistance (PMQR) genes in the tribe Proteeae, 81 isolates (65 Proteus spp., 12 Morganella morganii and 4 Providencia stuartii) consecutively collected in 66 hospitals belonging to the WHONET-Argentina Resistance Surveillance Network were studied. Of the 81 isolates, 50 (62%) were susceptible to quinolones [43/65 (66%) Proteus spp. and 7/12 (58%) M. morganii). The remaining 31 isolates (22 Proteus spp., 5 M. morganii and all P. stuartii) showed high-level resistance to nalidixic acid (NAL) and decreased susceptibility or resistance to ciprofloxacin. All NAL-resistant isolates harboured mutations associated with quinolone resistance (MAQRs) in both gyrA (S83I/R) and parC (S80I/R), and some also had MAQRs in gyrB (S464Y/F). The unique PMQR gene detected was qnrD, which was found in 2/81 isolates (Proteus mirabilis Q1084 and Proteus vulgaris Q5169), giving a prevalence of 2.5% in Proteeae. These two isolates were from different geographical regions and both harboured MAQRs in gyrA and parC. The qnrD genes were located on the related plasmids pEAD1-1 (2683bp) and pEAD1-2 (2669bp). Plasmid pEAD1-1 was 100% identical to pCGH15 and differed in only three nucleotides from pDIJ09-518a, which were previously found in clinical isolates of P. mirabilis (China) and Providencia rettgeri (France), respectively, whilst pEAD1-2 was not previously described. The extended-spectrum ß-lactamase CTX-M-2 was found in 27% (22/81) of the isolates and was significantly associated with quinolone resistance but not with qnrD (only P. mirabilis Q1084 expressed CTX-M-2). This is the first report of qnrD in the Americas.
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Introdução. Quinolonas são antimicrobianos sintéticos que inibem as enzimas DNA-girase e topoisomerase IV resultando na morte bacteriana. São altamente eficazes no tratamento de infecções bacterianas, especialmente causadas por bactérias Gram negativas, e portanto amplamente utilizados na medicina humana e veterinária, na qual também são empregados como profiláticos. Porém, o uso indiscriminado e inadequado levou ao aumento de bactérias resistentes a estes compostos. Esta resistência pode ocorrer devido a mutações nas enzimas DNA-girase e topoisomerase IV, e também por genes contidos em plasmídeos. Estes últimos são os principais responsáveis pela disseminação e circulação da resistência entre o meio ambiente e o ambiente hospitalar. Objetivos. Pesquisar genes de resistência a antimicrobianos do grupo das quinolonas em bactérias Gram negativas de origem clínica e ambiental que apresentam resistência fenotípica a este grupo. Material e Métodos. 73 cepas de Enterobacteriaceae e Aeromonas sp. de origem clínica e ambiental foram selecionadas para o estudo, e avaliadas quanto à sensibilidade aos antimicrobianos do grupo das quinolonas e à pesquisa de genes de resistência a este mesmo grupo e mutações no gene que codifica a enzima DNA-girase por meio de PCR e sequenciamento. Resultados. Das 73 cepas previamente selecionadas para compor o estudo, 65 foram utilizadas, devido à exclusão de perfis clonais similares. Nestas, foram observados os genes, qnrS1 (1,5 por cento ), qnrS2 (26,2 por cento ), qnrB1 (3,1 por cento ), qnrB19 (12,3 por cento ), qnrD1 (1,5 por cento ), aac(6)-Ib-cr (10,8 por cento ), oqxA (43,1 por cento ) e oqxB (41,5 por cento ), e duas variantes determinadas qnrB-like (3,1 por cento ) e qnrB69-like (1,5 por cento ). Os genes qnrA, qnrC e qepA não foram identificados. Mutações na enzima DNA-girase foram observadas em 97,9 por cento das cepas positivas para algum dos genes pesquisados...
Introduction. Quinolones are synthetic antimicrobial agents that inhibit DNA gyrase and topoisomerase IV enzymes resulting in bacterial death. They are highly effective in the treatment of bacterial infections, especially the ones caused by Gram negative bacteria, as well as for prophylaxy. Therefore they are widely used in human and veterinary medicine. However, indiscriminate and improper use led to an increase of bacteria resistance to these compounds. This resistance can be due to mutations in DNA gyrase and topoisomerase IV enzymes and also by genes contained in plasmids, which are mainly responsible for the spread and transmission of resistance between the environment and the hospital set. Objectives. To search for genes of resistance to quinolone antimicrobial agents in Gram-negative bacteria from clinical and environmental strains that present phenotypic resistance to this group. Material and Methods. 73 strains of Enterobacteriaceae and Aeromonas spp., from clinical and environmental origin, were selected for this study, and evaluated for antimicrobial susceptibility of quinolone and search of resistance genes in this same group and also for mutations in the gene encoding the enzyme DNA gyrase by PCR and sequencing. Results. Of the 73 strains previously selected to compose this study, 65 were used, due to the exclusion of similar clonal profiles. In these, genes qnrS1 (1.5 per cent ), qnrS2 (26.2 per cent ) qnrB1 (3.1 per cent ), qnrB19 (12.3 per cent ) qnrD1 (1.5 per cent ) aac(6')-Ib-cr (10.8 per cent ) oqxA (43.1 per cent ) and oqxB (41.5 per cent ) were observed, and two variants were named as qnrB-like (3.1 per cent ) and qnrB69-like (1.5 per cent ). The qnrA, qnrC and qepA genes were not identified. Mutations in DNA gyrase enzyme were observed in 97.9 per cent of the positive strains for at least one of the genes studied. It was possible to establish the association of aac(6')-Ib-cr with class 1 integron gene in four strains...