RESUMO
The emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKp) is a growing concern due to its high mortality and limited treatment options. Although hypermucoviscosity is crucial for CR-hvKp infection, the role of changes in bacterial mucoviscosity in the host colonization and persistence of CR-hvKp is not clearly defined. Herein, we observed a phenotypic switch of CR-hvKp from a hypermucoviscous to a hypomucoviscous state in a patient with scrotal abscess and urinary tract infection (UTI). This switch was attributed to decreased expression of rmpADC, the regulator of mucoid phenotype, caused by deletion of the upstream insertion sequence ISKpn26. Postswitching, the hypomucoid variant showed a 9.0-fold decrease in mice sepsis mortality, a >170.0-fold reduction in the ability to evade macrophage phagocytosis in vitro, and an 11.2- to 40.9-fold drop in growth rate in normal mouse serum. Conversely, it exhibited an increased residence time in the mouse urinary tract (21 vs. 6 d), as well as a 216.4-fold boost in adhesion to bladder epithelial cells and a 48.7% enhancement in biofilm production. Notably, the CR-hvKp mucoid switch was reproduced in an antibiotic-free mouse UTI model. The in vivo generation of hypomucoid variants was primarily associated with defective or low expression of rmpADC or capsule synthesis gene wcaJ, mediated by ISKpn26 insertion/deletion or base-pair insertion. The spontaneous hypomucoid variants also outcompeted hypermucoid bacteria in the mouse urinary tract. Collectively, the ISKpn26-associated mucoid switch in CR-hvKp signifies the antibiotic-independent host adaptive evolution, providing insights into the role of mucoid switch in the persistence of CR-hvKp.
Assuntos
Carbapenêmicos , Infecções por Klebsiella , Klebsiella pneumoniae , Infecções Urinárias , Klebsiella pneumoniae/patogenicidade , Klebsiella pneumoniae/genética , Animais , Humanos , Infecções por Klebsiella/microbiologia , Infecções Urinárias/microbiologia , Camundongos , Carbapenêmicos/farmacologia , Masculino , Virulência/genética , Antibacterianos/farmacologia , Sistema Urinário/microbiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismoRESUMO
Seven mobile oxazolidinone resistance genes, including cfr, cfr(B), cfr(C), cfr(D), cfr(E), optrA, and poxtA, have been identified to date. The cfr genes code for 23S rRNA methylases, which confer a multiresistance phenotype that includes resistance to phenicols, lincosamides, oxazolidinones, pleuromutilins, and streptogramin A compounds. The optrA and poxtA genes code for ABC-F proteins that protect the bacterial ribosomes from the inhibitory effects of oxazolidinones. The optrA gene confers resistance to oxazolidinones and phenicols, while the poxtA gene confers elevated MICs or resistance to oxazolidinones, phenicols, and tetracycline. These oxazolidinone resistance genes are most frequently found on plasmids, but they are also located on transposons, integrative and conjugative elements (ICEs), genomic islands, and prophages. In these mobile genetic elements (MGEs), insertion sequences (IS) most often flanked the cfr, optrA, and poxtA genes and were able to generate translocatable units (TUs) that comprise the oxazolidinone resistance genes and occasionally also other genes. MGEs and TUs play an important role in the dissemination of oxazolidinone resistance genes across strain, species, and genus boundaries. Most frequently, these MGEs also harbor genes that mediate resistance not only to antimicrobial agents of other classes, but also to metals and biocides. Direct selection pressure by the use of antimicrobial agents to which the oxazolidinone resistance genes confer resistance, but also indirect selection pressure by the use of antimicrobial agents, metals, or biocides (the respective resistance genes against which are colocated on cfr-, optrA-, or poxtA-carrying MGEs) may play a role in the coselection and persistence of oxazolidinone resistance genes.
Assuntos
Oxazolidinonas , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Genes Bacterianos/genética , Bactérias Gram-Negativas , Bactérias Gram-Positivas , Testes de Sensibilidade Microbiana , Oxazolidinonas/farmacologiaRESUMO
OBJECTIVES: To characterize the relationship of tet(X4)-positive isolates from different hosts and environments. METHODS: PCR and MALDI-TOF MS were used to identify the tet(X4)-positive isolates. The MICs of 13 antimicrobial agents were determined by broth microdilution. Illumina technology was used to sequence all of the isolates. One isolate was randomly selected from Escherichia coli ST761 clones for long-read sequencing to obtain plasmid sequences. Bioinformatics analysis was used to determine the phylogeny of 46 tet(X4)-positive E. coli ST761 strains. RESULTS: A total of 12 tet(X4)-positive isolates, 8 E. coli and 4 Aeromonas simiae, were obtained from six lairages of a slaughterhouse. These isolates exhibited resistance to at least three classes of antimicrobials, including tigecycline. The majority of them, seven E. coli and three A. simiae, represent separate clonal groups. Notably, the seven E. coli isolates belonged to ST761, a common ST carrying the tet(X4) gene that has been identified in 39 isolates from animals, meat, wastewater and humans from seven Chinese provinces. All 46 tet(X4)-positive E. coli ST761 strains from various sources have a close phylogenetic relationship (0-72 SNPs), with a high nucleotide sequence similarity of resistance genes and the tet(X4)-carrying IncX1-IncFIA(HI1)-IncFIB(K) hybrid plasmid, indicating a clonal relationship of tet(X4)-positive E. coli ST761 among animals, food, the environment and humans. CONCLUSIONS: The clonal relationship of tet(X4)-positive E. coli ST761 between humans and animals poses a previously underestimated threat to public health. To the best of our knowledge, this is the first description of tet(X4)-positive A. simiae.
Assuntos
Farmacorresistência Bacteriana , Escherichia coli , Animais , Antibacterianos/farmacologia , Farmacorresistência Bacteriana/genética , Humanos , Testes de Sensibilidade Microbiana , Filogenia , Plasmídeos/genética , TigeciclinaRESUMO
OBJECTIVES: To reconstruct the evolutionary history and genomic epidemiology of Staphylococcus aureus ST9 in China. METHODS: Using WGS analysis, we described the phylogeny of 131 S. aureus ST9 isolates collected between 2002 and 2016 from 11 provinces in China, including six clinical samples from Taiwan. We also investigated the complex structure and distribution of the lsa(E)-carrying multiresistance gene cluster, and genotyped prophages in the genomes of the ST9 isolates. RESULTS: ST9 was subdivided into one major (nâ=â122) and one minor (nâ=â9) clade. Bayesian phylogeny predicted the divergence of ST9 isolates in pig farming in China as early as 1987, which then evolved rapidly in the following three decades. ST9 isolates shared similar multiresistance properties, which were likely acquired before the ST9 emergence in China. The accessory genome is highly conserved, and ST9 harboured similar sets of phages, but lacked certain virulence genes. CONCLUSIONS: Host exchange and regional transmission of ST9 have occurred between pigs and humans. Pig rearing and trading might have favoured gene exchanges between ST9 isolates. Resistance genes, obtained from the environment and other isolates, were stably integrated into the chromosomal DNA. The abundance of resistance genes among ST9 is likely attributed to the extensive use of antimicrobial agents in livestock. Phages are present in the genomes of ST9 and may play a role in the rapid evolution of this ST. Although human ST9 infections are rare, ST9 isolates may constitute a potential risk to public health as a repository of antimicrobial resistance genes.
Assuntos
Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Animais , Antibacterianos , Teorema de Bayes , China/epidemiologia , Genômica , Staphylococcus aureus Resistente à Meticilina/genética , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/veterinária , Staphylococcus aureus , Suínos , Taiwan/epidemiologiaRESUMO
This study aimed to investigate the prevalence, molecular characteristics and antibiotic resistance of Staphylococcus aureus isolates from yak butter in Tibet, China. A total of 218 yak butter samples were collected from retail stores in Tibet and screened for Staph. aureus. Furthermore, the virulence genes, resistance genes, antimicrobial susceptibility, and molecular typing [pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, and staphylococcal protein A (spa) typing] of Staph. aureus isolates were detected. The results showed that 12.4% of yak butter samples were contaminated with Staph. aureus, including 5 samples positive for methicillin-resistant Staph. aureus (MRSA). Among all isolates, 96.3% harbored one or more virulence genes, including classical (sea and sec), novel enterotoxin-encoding genes (seh, sek, sel, and seq), and hemolysin genes (hla and hld). All isolates were resistant to at least 2 different antibiotic classes, and the isolates were most commonly resistant to sulfonamides, ß-lactams, and erythromycin. For resistance genes, blaZ (74.1%) was most frequently detected, followed by dfrG (51.9%), erm(B) (22.2%), mecA (18.5%), tet(K) (14.8%), aph(2â³)-Ia, aph(3')-III, and ant(6)-Ia (11.1% for each), and erm(C) (7.4%). We detected 8 spa types, 6 sequence types (ST), and 5 clonal complex (CC) types. In addition, 1 isolate of Staph. aureus was nontypeable. We found that CC1-ST1-t559 (55.6%) was the most predominant clone, followed by CC59-ST59-t437 (11.1%), CC5-ST5-t002 (7.4%), CC1-ST1, CC1-ST1-t114, CC1-ST573-t4938, CC1-ST573-t8915, CC30-ST30-t021, and CC25-ST25-t167 (3.7% for each). For PFGE typing, a total of 5 clusters and 15 pulsotypes were generated, and some isolates from different samples showed indistinguishable pulsotypes. Our findings suggest that yak butter produced in Tibet, China, could be contaminated by Staph. aureus strains, including MRSA strains, carrying various virulence and resistance genes, representing multiple antimicrobial resistance phenotypes. The presence of potentially virulent and antibiotic-resistant Staph. aureus strains in yak butter poses a potential threat to consumers, and appropriate measures need to be taken in the production chain to reduce the occurrence of Staph. aureus in yak butter.
Assuntos
Doenças dos Bovinos , Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Animais , Antibacterianos/farmacologia , Manteiga , Bovinos , China , Staphylococcus aureus Resistente à Meticilina/genética , Testes de Sensibilidade Microbiana/veterinária , Tipagem de Sequências Multilocus/veterinária , Prevalência , Infecções Estafilocócicas/veterinária , Staphylococcus aureus/genética , TibetRESUMO
Colistin resistance has attracted substantial attention after colistin was considered as a last-resort drug for the treatment of infections caused by carbapenem-resistant and/or multidrug-resistant (MDR) Gram-negative bacteria in clinical settings. However, with the discovery of highly mobile colistin resistance (mcr) genes, colistin resistance has become an increasingly urgent issue worldwide. Despite many reviews, which summarized the prevalence, mechanisms, and structures of these genes in bacteria of human and animal origin, studies on the prevalence of mobile colistin resistance genes in aquaculture and their transmission between animals and humans remain scarce. Herein, we review recent reports on the prevalence of colistin resistance genes in animals, especially wildlife and aquaculture, and their possibility of transmission to humans via the food chain. This review also gives some insights into the routine surveillance, changing policy and replacement of polymyxins by polymyxin derivatives, molecular inhibitors, and traditional Chinese medicine to tackle colistin resistance.
Assuntos
Animais Domésticos/microbiologia , Antibacterianos/farmacologia , Bactérias/efeitos dos fármacos , Colistina/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Animais , Aquicultura , Bactérias/genética , Humanos , Plasmídeos/genéticaRESUMO
In this study, we explored the prevalence of oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) in staphylococcal food poisoning outbreak isolates and foodborne isolates, and then investigated their molecular characteristics, classical staphylococcal enterotoxins (SEs), and drug resistance. Eight (2.9%) of 275 isolates from food poisoning outbreaks and 7 (3.8%) of 184 isolates from retail foods were identified as OS-MRSA isolates. Among the 15 OS-MRSA isolates, the most frequently detected toxin genes were hld (100%), hla (93.3%), pvl (80.0%), and hlb (46.7%) followed by seg and seq (33.3%, each), hlg (26.7%), seb and hlgv (20.0%, each), sec, seh, sel, sep, and tst (13.3%, each), and sei, sem, sen, and seo (6.7%, each). None of isolates carried other tested virulence genes. The most frequently detected classical SEs were SEB and SEC (26.7%, each), followed by SEA and SEE (20.0%, each), and SED (6.7%). Resistance was most frequently observed in ampicillin, penicillin, and cefoxitin (100%, each), followed by trimethoprim/sulfamethoxazole (93.3%), erythromycin (73.3%), amoxicillin/clavulanic acid (46.7%), tetracyclines (26.7%), and ciprofloxacin (6.7%). All isolates were susceptible to other tested antibiotics. A dominant molecular type belonged to ST398-IVa-t034 (26.7%), followed by ST59-IVa-t437 (20.0%), ST88-III-t14340 and ST1-IVa-t114 (13.3%, each), and ST5-II-t002, ST630-t4549, ST5-II, and ST4495-t10738 (6.7%, each). Our findings indicated that OS-MRSA strains had a low prevalence rate among outbreak strains and foodborne strains, which frequently harbored SCCmec IVa, and carried a variety of toxin genes, and also expressed numerous classical SEs. In addition, all OS-MRSA isolates were susceptible to the majority of antibacterial agents except ß-lactam. Our study is the first to report that OS-MRSA isolates are associated with food poisoning outbreaks worldwide.
Assuntos
Oxacilina/farmacologia , Intoxicação Alimentar Estafilocócica/epidemiologia , Staphylococcus aureus/isolamento & purificação , Antibacterianos/farmacologia , China/epidemiologia , Surtos de Doenças , Farmacorresistência Bacteriana , Contaminação de Alimentos , Microbiologia de Alimentos , Genes Bacterianos , Humanos , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Staphylococcus aureus/efeitos dos fármacosRESUMO
Objectives: To investigate the presence and molecular characteristics of oxazolidinone resistance genes cfr and optrA in staphylococci from household animals in rural China. Methods: Various samples were collected from household animals in 12 rural villages. Staphylococcal isolates showing florfenicol MICs ≥10 mg/L were identified and screened for the presence of cfr and/or optrA. PCR-positive isolates were characterized by antimicrobial susceptibility testing, S1 nuclease PFGE and Southern blotting. WGS data were analysed to identify the core-genome phylogenetic profile of each isolate as well as the genetic environment of cfr and/or optrA. Results: Nine optrA-positive (seven Staphylococcus sciuri and two Staphylococcus simulans) and 10 cfr-positive staphylococci were identified from eight and five villages, respectively. The gene optrA was chromosomally encoded in all nine isolates, whereas cfr was located on a plasmid in one S. sciuri and three Staphylococcus saprophyticus and in the chromosomal DNA of single Staphylococcus cohnii and Staphylococcus lentus isolates and two S. sciuri isolates. The remaining two cfr-carrying Staphylococcus haemolyticus isolates were indistinguishable by PFGE. Most optrA- or cfr-carrying staphylococci also harboured phenicol, tetracycline and/or macrolide-lincosamide-streptogramin B resistance genes. Genetic environment analysis showed that, for the first time, optrA was associated with transposon Tn6261, while cfr was adjacent to both a tnp (transposase) gene and a Tn558 transposon. Conclusions: The current study reveals for the first time the wide distribution of oxazolidinone resistance genes optrA and cfr in household animals in rural areas of China and is the first identification of optrA in S. simulans isolates.
Assuntos
Animais Domésticos , Anti-Infecciosos/farmacologia , Farmacorresistência Bacteriana , Oxazolidinonas/farmacologia , Infecções Estafilocócicas/veterinária , Staphylococcus/isolamento & purificação , Animais , Proteínas de Bactérias/genética , Southern Blotting , China , Eletroforese em Gel de Campo Pulsado , Genótipo , Testes de Sensibilidade Microbiana , Filogenia , Reação em Cadeia da Polimerase , Infecções Estafilocócicas/microbiologia , Staphylococcus/classificação , Staphylococcus/genética , Sequenciamento Completo do GenomaRESUMO
Lincosamide resistance in staphylococci is based on the expression of a number of genes which specify three major resistance mechanisms: (i) enzymatic inactivation by lincosamide nucleotidyltransferases, (ii) ribosome protection by ABC-F proteins, and (iii) methylation of the ribosomal target sites in the 23S rRNA by Cfr or Erm methylases. So far, only two lnu genes, lnu(A) and lnu(B), which code for different types of lincosamide nucleotidyltransferases, have been found in staphylococci. The ABC-F proteins are encoded by genes of the vga, lsa and sal classes. The corresponding proteins exhibit ATP-binding domains, but lack transmembrane regions. So far, vga(A) genes - including the variant genes vga(A)V and vga(A)LC -, vga(C) genes and vga(E) genes - including the variant gene vga(E)V -, the lsa genes lsa(B) and lsa(E), as well as the sal(A) gene have been identified in staphylococci. The aforementioned genes, except lsa(B), confer resistance not only to lincosamides, but also to pleuromutilins and streptogramin A. The cfr and erm genes code for methylases which target the adenine residues at positions 2503 and 2048 in the 23S rRNA, respectively. While the cfr gene confers resistance to phenicols, lincosamides, oxazolidinones, pleuromutilins and streptogramin A, the erm genes mediate resistance to macrolides, lincosamides and streptogramin B. Many of the aforementioned lincosamide resistance genes are located on either plasmids or transposons and as such, can easily be disseminated across strain, species, and genus boundaries. The co-location of other antimicrobial resistance genes on the same mobile genetic element facilitates co-selection and persistence of the lincosamide resistance genes under the selective pressure imposed by other antimicrobial agents.
Assuntos
Farmacorresistência Bacteriana Múltipla/genética , Lincosamidas/uso terapêutico , Plasmídeos/genética , Staphylococcus/genética , Antibacterianos/efeitos adversos , Antibacterianos/uso terapêutico , Genes Bacterianos , Humanos , Macrolídeos/efeitos adversos , Macrolídeos/uso terapêutico , RNA Ribossômico 23S/genética , Staphylococcus/efeitos dos fármacos , Staphylococcus/patogenicidade , Estreptogramina B/efeitos adversos , Estreptogramina B/uso terapêuticoRESUMO
Macrolide resistance in staphylococci is based on the expression of a number of genes which specify four major resistance mechanisms: (i) target site modification by methylation of the ribosomal target site in the 23S rRNA, (ii) ribosome protection via ABC-F proteins, (iii) active efflux via Major Facilitator Superfamily (MFS) transporters, and (iv) enzymatic inactivation by phosphotransferases or esterases. So far, 14 different classes of erm genes, which code for 23S rRNA methylases, have been reported to occur in staphylococci from humans, animals and environmental sources. Inducible or constitutive expression of the erm genes depends on the presence and intactness of a regulatory region known as translational attenuator. The erm genes commonly confer resistance not only to macrolides, but also to lincosamides and streptogramin B compounds. In contrast, the msr(A) gene codes for an ABC-F protein which confers macrolide and streptogramin B resistance whereas the mef(A) gene codes for a Major Facilitator Superfamily protein that can export only macrolides. Enzymatic inactivation of macrolides may be due to the macrolide phosphotransferase gene mph(C) or the macrolide esterase genes ere(A) or ere(B). Many of these macrolide resistance genes are part of either plasmids, transposons, genomic islands or prophages and as such, can easily be transferred across strain, species and genus boundaries. The co-location of other antimicrobial or metal resistance genes on the same mobile genetic element facilitates co-selection and persistence of macrolide resistance genes under the selective pressure of metals or other antimicrobial agents.
Assuntos
Proteínas de Bactérias/genética , Farmacorresistência Bacteriana Múltipla/genética , Plasmídeos/genética , Staphylococcus/genética , Humanos , Macrolídeos/efeitos adversos , Macrolídeos/uso terapêutico , Testes de Sensibilidade Microbiana , Plasmídeos/efeitos dos fármacos , RNA Ribossômico 23S/efeitos dos fármacos , RNA Ribossômico 23S/genética , Staphylococcus/efeitos dos fármacos , Staphylococcus/patogenicidade , Estreptogramina B/efeitos adversos , Estreptogramina B/uso terapêuticoRESUMO
The recently discovered colistin resistance element, mcr-1, adds to the list of antimicrobial resistance genes that rapidly erode the antimicrobial efficacy of not only the commonly used antibiotics but also the last-line agents of carbapenems and colistin. This study investigated the prevalence of the mobile colistin resistance determinant mcr-1 in Salmonella strains recovered from clinical settings in China and the transmission potential of mcr-1-bearing mobile elements harbored by such isolates. The mcr-1 gene was recoverable in 1.4% of clinical isolates tested, with the majority of them belonging to Salmonella enterica serotype Typhimurium. These isolates exhibited diverse pulsed-field gel electrophoresis (PFGE) profiles and high resistance to antibiotics other than colistin and particularly to cephalosporins. Plasmid analysis showed that mcr-1 was carried on a variety of plasmids with sizes ranging from â¼30 to â¼250 kb, among which there were conjugative plasmids of â¼30 kb, â¼60 kb, and â¼250 kb and nonconjugative plasmids of â¼140 kb, â¼180 kb, and â¼240 kb. Sequencing of representative mcr-1-carrying plasmids revealed that all conjugative plasmids belonged to the IncX4, IncI2, and IncHI2 types and were highly similar to the corresponding types of plasmids reported previously. Nonconjugative plasmids all belonged to the IncHI2 type, and the nontransferability of these plasmids was attributed to the loss of a region carrying partial or complete tra genes. Our data revealed that, similar to the situation in Escherichia coli, mcr-1 transmission in Salmonella was accelerated by various plasmids, suggesting that transmission of mcr-1-carrying plasmids between different species of Enterobacteriaceae may be a common event.
Assuntos
Proteínas de Bactérias/genética , Farmacorresistência Bacteriana Múltipla/genética , Etanolaminofosfotransferase/genética , Sequências Repetitivas Dispersas/genética , Plasmídeos/genética , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética , Antibacterianos/farmacologia , China , Colistina/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Humanos , Testes de Sensibilidade Microbiana , Salmonella typhimurium/isolamento & purificaçãoAssuntos
Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Animais , Antibacterianos/farmacologia , Lincosamidas , Staphylococcus aureus Resistente à Meticilina/genética , Testes de Sensibilidade Microbiana , Família Multigênica/genética , Infecções Estafilocócicas/genética , Infecções Estafilocócicas/veterinária , SuínosRESUMO
Metallo-ß-lactamase gene blaVIM was identified on the chromosome of four Pseudomonas sp. isolates from a chicken farm, including one Pseudomonas aeruginosa isolate from a swallow (Yanornis martini), one Pseudomonas putida isolate from a fly, and two P. putida isolates from chickens. The four isolates shared two variants of blaVIM-carrying genomic contexts that resemble the corresponding regions of clinical metallo-ß-lactamase-producing Pseudomonas spp. Our study suggests that the surveillance of carbapenemase-producing bacteria in livestock and their surrounding environment is urgently needed.
Assuntos
Pseudomonas/enzimologia , Animais , Proteínas de Bactérias/metabolismo , Carbapenêmicos/farmacologia , Galinhas , Testes de Sensibilidade Microbiana , Pseudomonas/efeitos dos fármacos , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/enzimologia , beta-Lactamases/metabolismoRESUMO
The aim of this study was to investigate the prevalence of the polymyxin resistance gene mcr-1 in Enterobacteriaceae from environmental water sources in Hangzhou, China. Colistin-resistant bacteria were isolated from environmental water samples using an enrichment broth culture method, were screened for mcr-1, and then were analyzed for the location and transferability of mcr-1 Isolates positive for mcr-1 were further examined to determine their susceptibility profiles and were screened for the presence of additional resistance genes. Twenty-three mcr-1-positive isolates (16 Escherichia coli, two Citrobacter freundii, two Klebsiella oxytoca, two Citrobacter braakii, and one Enterobacter cloacae) were isolated from 7/9 sampling locations; of those, eight mcr-1-positive isolates also contained ß-lactamase-resistance genes, eight contained qnrS, and 10 contained oqx No mcr-2-positive isolates were identified. The majority of isolates demonstrated a low to moderate level of colistin resistance. Transconjugation was successfully conducted from 14 of the 23 mcr-1-positive isolates, and mcr-1 was identified on plasmids ranging from 60 to 220 kb in these isolates. Conjugation and hybridization experiments revealed that mcr-1 was chromosome-borne in only three isolates. Pulsed-field gel electrophoresis showed that the majority of E. coli isolates belonged to different clonal lineages. Multilocus sequence typing analysis revealed that sequence type 10 (ST10) was the most prevalent, followed by ST181 and ST206. This study demonstrates the utility of enrichment broth culture for identifying environmental mcr-1-positive isolates. Furthermore, it highlights the importance of responsible agriculture and clinical use of polymyxins to prevent further widespread dissemination of polymyxin-resistant pathogens.
Assuntos
Proteínas de Bactérias/genética , Cromossomos Bacterianos/genética , Farmacorresistência Bacteriana/genética , Enterobacteriaceae/genética , Plasmídeos/genética , Microbiologia da Água , Antibacterianos/farmacologia , Técnicas de Tipagem Bacteriana , China , Colistina/farmacologia , Eletroforese em Gel de Campo Pulsado , Enterobacteriaceae/classificação , Enterobacteriaceae/efeitos dos fármacos , Proteínas de Escherichia coli/genética , Tipagem de Sequências Multilocus , Polimixinas/farmacologia , Resistência beta-Lactâmica/genética , beta-Lactamases/genéticaAssuntos
Staphylococcus aureus Resistente à Meticilina , Estreptogramina B , Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/genética , Lincosamidas/farmacologia , Macrolídeos/farmacologia , Staphylococcus aureus Resistente à Meticilina/genética , Testes de Sensibilidade Microbiana , Estreptogramina B/farmacologiaRESUMO
Objectives: To identify a novel putative lincosamide resistance gene determinant in a swine Enterococcus faecalis E531 exhibiting a lincosamide resistance/macrolide susceptibility (L R M S ) phenotype and to determine its location and genetic environment. Methods: The whole genomic DNA of E. faecalis E531, which tested negative for the known lincosamide nucleotidyltransferase genes, was sequenced. A putative lincosamide resistance gene determinant was cloned into an Escherichia coli - E. faecalis shuttle vector (pAM401) and transformed into E. faecalis JH2-2. The MICs were determined by the microbroth dilution method. Inactivity of lincomycin was examined by UPLC-MS/MS. Inverse PCR and primer walking were used to explore the genetic environment based on the assembled sequence. Results: A novel resistance gene, designated lnu (G), which encodes a putative lincosamide nucleotidyltransferase, was found in E. faecalis E531. The deduced Lnu(G) amino acid sequence displayed 76.0% identity to Lnu(B) in Enterococcus faecium . Both E. faecalis E531 and E. faecalis JH2-2 harbouring pAM401- lnu (G) showed a 4-fold increase in the MICs of lincomycin, compared with E. faecalis JH2-2 or E. faecalis JH2-2 harbouring empty vector pAM401 only. UPLC-MS/MS demonstrated that the Lnu(G) enzyme catalysed adenylylation of lincomycin. The genetic environment analysis revealed that the lnu (G) gene was embedded into a novel putative transposon, designated Tn 6260 , which was active. Conclusions: A novel lincosamide nucleotidyltransferase gene lnu (G) was identified in E. faecalis . The location of the lnu (G) gene on a mobile element Tn 6260 makes it easy to disseminate.
Assuntos
Antibacterianos/farmacologia , Elementos de DNA Transponíveis , Farmacorresistência Bacteriana , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/enzimologia , Lincomicina/farmacologia , Nucleotidiltransferases/genética , Animais , Enterococcus faecalis/genética , Enterococcus faecalis/isolamento & purificação , Genoma Bacteriano , Infecções por Bactérias Gram-Positivas/veterinária , Testes de Sensibilidade Microbiana , Análise de Sequência de DNA , SuínosRESUMO
The multiresistance gene cfr was found in two porcine Escherichia coli isolates, one harboring it on the conjugative 33,885-bp plasmid pFSEC-01, the other harboring it in the chromosomal DNA. Sequence analysis of pFSEC-01 revealed that a 6,769-bp fragment containing the cfr gene bracketed by two IS26 elements was inserted into a plasmid closely related to pEA3 from the plant pathogen Erwinia amylovora, suggesting that pFSEC-01 may be transferred between different bacterial genera of both animal and plant origin.
Assuntos
Erwinia amylovora/genética , Infecções por Escherichia coli/veterinária , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica , Metiltransferases/genética , Plasmídeos/química , Doenças dos Suínos/microbiologia , Animais , Antibacterianos/farmacologia , Conjugação Genética , Farmacorresistência Bacteriana Múltipla/genética , Erwinia amylovora/efeitos dos fármacos , Erwinia amylovora/isolamento & purificação , Escherichia coli/efeitos dos fármacos , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/metabolismo , Metiltransferases/metabolismo , Testes de Sensibilidade Microbiana , Fases de Leitura Aberta , Doenças das Plantas/microbiologia , Plantas , Plasmídeos/metabolismo , Análise de Sequência de DNA , SuínosRESUMO
A total of 57 methicillin-resistant Staphylococcus aureus (MRSA) isolates and 475 methicillin-resistant coagulase-negative staphylococci (MRCoNS) collected from pigs in the Guangdong province of China in 2014 were investigated for the presence of the novel oxazolidinone-phenicol resistance gene optrA The optrA gene was detected in 6.9% (n = 33) of the MRCoNS, all of which were Staphylococcus sciuri isolates, but in none of the MRSA isolates. Five optrA-carrying methicillin-resistant (MR) S. sciuri isolates also harbored the multiresistance gene cfr Pulsed-field gel electrophoresis (PFGE) and dru typing of the 33 optrA-carrying MR S. sciuri isolates revealed 25 patterns and 5 sequence types, respectively. S1 nuclease PFGE and Southern blotting confirmed that optrA was located in the chromosomal DNAs of 29 isolates, including 1 cfr-positive isolate. The remaining four isolates harbored a â¼35-kb pWo28-3-like plasmid on which optrA and cfr were located together with other resistance genes, as confirmed by sequence analysis. Six different types of genetic environments (types I to VI) of the chromosome-borne optrA genes were identified; these types had the optrA gene and its transcriptional regulator araC in common. Tn558 was found to be associated with araC-optrA in types II to VI. The optrA gene in types II and III was found in close proximity to the ccr gene complex of the respective staphylococcal cassette chromosome mec element (SCCmec). Since oxazolidinones are last-resort antimicrobial agents for the control of serious infections caused by methicillin-resistant staphylococci in humans, the location of the optrA gene close to the ccr complex is an alarming observation.
Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana Múltipla/genética , Oxazolidinonas/farmacologia , Staphylococcus/efeitos dos fármacos , Staphylococcus/genética , Animais , Fator de Transcrição AraC/genética , China , Resistência Microbiana a Medicamentos/genética , Eletroforese em Gel de Campo Pulsado , Resistência a Meticilina/genética , Tipagem Molecular , Staphylococcus/isolamento & purificação , SuínosRESUMO
OBJECTIVES: To identify and characterize the oxazolidinone/phenicol resistance gene optrA in Staphylococcus isolates. METHODS: Fifty porcine staphylococci with florfenicol MICs of ≥16 mg/L were screened by PCR for the presence of the optrA gene. Transferability of optrA was examined by transformation and conjugation. Functionality of this gene was confirmed by cloning and expression in a susceptible Staphylococcus host. The optrA-carrying plasmid was completely sequenced and analysed. RESULTS: A single Staphylococcus sciuri was optrA positive. This isolate carried the optrA gene on the 60â563 bp multiresistance plasmid pWo28-3, which also harboured the resistance genes, cfr, fexA, aadD, ble and aacA-aphD. Plasmid pWo28-3 is composed of three regions (A, B and C). Region A, which harboured all resistance genes except optrA, showed ≥99.8% nucleotide sequence identity to the corresponding region of plasmids pJP1 and pJP1-like from Jeotgalicoccus pinnipedialis and Staphylococcus lentus, respectively. The optrA gene located in region B differed from the optrA gene of the Enterococcus faecalis plasmid pE349 by four nucleotide substitutions, which also resulted in amino acid substitutions. This optrA variant also conferred resistance to oxazolidinones and phenicols in staphylococci. The 28 genes in region C represent the plasmid backbone and were apparently acquired from staphylococci, enterococci and nosocomiicocci. CONCLUSIONS: This is the first report of the optrA gene in staphylococci and of the coexistence of optrA and cfr on the same plasmid. Dissemination of this plasmid will substantially limit the efficacy of oxazolidinones. Surveillance of optrA in staphylococci of both human and animal origin is urgently warranted.