Antibiotic-Resistant Escherichia coli and Class 1 Integrons in Humans, Domestic Animals, and Wild Primates in Rural Uganda. - Related Documents




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555101.0000Antibiotic-Resistant Escherichia coli and Class 1 Integrons in Humans, Domestic Animals, and Wild Primates in Rural Uganda. Antibiotic resistance is a global concern, although it has been studied most extensively in developed countries. We studied Escherichia coli and class 1 integrons in western Uganda by analyzing 1,685 isolates from people, domestic animals, and wild nonhuman primates near two national parks. Overall, 499 isolates (29.6%) were resistant to at least one of 11 antibiotics tested. The frequency of resistance reached 20.3% of isolates for trimethoprim-sulfamethoxazole but was nearly zero for the less commonly available antibiotics ciprofloxacin (0.4%), gentamicin (0.2%), and ceftiofur (0.1%). The frequency of resistance was 57.4% in isolates from people, 19.5% in isolates from domestic animals, and 16.3% in isolates from wild nonhuman primates. Isolates of livestock and primate origin displayed multidrug resistance patterns identical to those of human-origin isolates. The percentage of resistant isolates in people was higher near Kibale National Park (64.3%) than near Bwindi Impenetrable National Park (34.6%), perhaps reflecting local socioeconomic or ecological conditions. Across antibiotics, resistance correlated negatively with the local price of the antibiotic, with the most expensive antibiotics (nalidixic acid and ciprofloxacin) showing near-zero resistance. Among phenotypically resistant isolates, 33.2% harbored class 1 integrons containing 11 common resistance genes arranged into nine distinct gene cassettes, five of which were present in isolates from multiple host species. Overall, these results show that phenotypic resistance and class 1 integrons are distributed broadly among E. coli isolates from different host species in this region, where local socioeconomic and ecological conditions may facilitate widespread diffusion of bacteria or resistance-conferring genetic elements.IMPORTANCE Antibiotic resistance is a global problem. This study, conducted in rural western Uganda, describes antibiotic resistance patterns in Escherichia coli bacteria near two forested national parks. Resistance was present not only in people, but also in their livestock and in nearby wild nonhuman primates. Multidrug resistance and class 1 integrons containing genes that confer resistance were common and were similar in people and animals. The percentage of resistant isolates decreased with increasing local price of the antibiotic. Antibiotic resistance in this setting likely reflects environmental diffusion of bacteria or their genes, perhaps facilitated by local ecological and socioeconomic conditions.201830171005
555510.9999New sequence types and multidrug resistance among pathogenic Escherichia coli isolates from coastal marine sediments. The spread of antibiotic-resistant microorganisms is widely recognized, but data about their sources, presence, and significance in marine environments are still limited. We examined 109 Escherichia coli strains from coastal marine sediments carrying virulence genes for antibiotic susceptibility, specific resistance genes, prevalence of class 1 and 2 integrons, and sequence type. Antibiotic resistance was found in 35% of strains, and multiple resistances were found in 14%; the resistances detected most frequently were against tetracycline (28%), ampicillin (16.5%), trimethoprim-sulfamethoxazole (13%), and streptomycin (7%). The highest prevalence of resistant strains was in phylogenetic group A, whereas phylogroup B2 exhibited a significantly lower frequency than all the other groups. Sixty percent of multiresistant strains harbored class 1 or 2 integrase genes, and about 50% carried resistance genes (particularly dfrA and aadA) linked to a class 1 integron. Multilocus sequence typing of 14 selected strains identified eight different types characteristic of extraintestinal pathogens and three new allelic combinations. Our data suggest that coastal marine sediment may be a suitable environment for the survival of pathogenic and antimicrobial-resistant E. coli strains capable of contributing to resistance spread via integrons among benthic bacteria, and they highlight a role for these strains in the emergence of new virulent genotypes.201222447595
289720.9998The Role of Flies in Disseminating Plasmids with Antimicrobial-Resistance Genes Between Farms. Dissemination of antimicrobial resistance is a major global public health concern. To clarify the role of flies in disseminating antimicrobial resistance between farms, we isolated and characterized tetracycline-resistant Escherichia coli strains isolated from flies and feces of livestock from four locations housing swine (abattoir, three farms) and three cattle farms. The percentages of isolates from flies resistant to tetracycline, dihydrostreptomycin, ampicillin, and chloramphenicol (80.8%, 61.5%, 53.8%, and 50.0%, respectively) and those from animal feces (80.5%, 78.0%, 41.5%, and 46.3%, respectively) in locations housing swine were significantly higher than those from cattle farms (p<0.05). The rates of resistance in E. coli derived from flies reflected those derived from livestock feces at the same locations, suggesting that antimicrobial resistance spreads between livestock and flies on the farms. The results of pulsed-field gel electrophoresis (PFGE) analysis showed that, with a few exceptions, all E. coli isolates differed. Two pairs of tetracycline-resistant strains harbored similar plasmids with the same tetracycline-resistance genes, although the origin (fly or feces), site of isolation, and PFGE patterns of these strains differed. Therefore, flies may disseminate the plasmids between farms. Our results suggest that flies may be involved not only in spreading clones of antimicrobial-resistant bacteria within a farm but also in the widespread dissemination of plasmids with antimicrobial resistance genes between farms.201526061440
555430.9998High prevalence of multidrug-tolerant bacteria and associated antimicrobial resistance genes isolated from ornamental fish and their carriage water. BACKGROUND: Antimicrobials are used to directly control bacterial infections in pet (ornamental) fish and are routinely added to the water these fish are shipped in to suppress the growth of potential pathogens during transport. METHODOLOGY/PRINCIPAL FINDINGS: To assess the potential effects of this sustained selection pressure, 127 Aeromonas spp. isolated from warm and cold water ornamental fish species were screened for tolerance to 34 antimicrobials. Representative isolates were also examined for the presence of 54 resistance genes by a combination of miniaturized microarray and conventional PCR. Forty-seven of 94 Aeromonas spp. isolates recovered from tropical ornamental fish and their carriage water were tolerant to > or =15 antibiotics, representing seven or more different classes of antimicrobial. The quinolone and fluoroquinolone resistance gene, qnrS2, was detected at high frequency (37% tested recent isolates were positive by PCR). Class 1 integrons, IncA/C broad host range plasmids and a range of other antibiotic resistance genes, including floR, bla(TEM-1), tet(A), tet(D), tet(E), qacE2, sul1, and a number of different dihydrofolate reductase and aminoglycoside transferase coding genes were also detected in carriage water samples and bacterial isolates. CONCLUSIONS: These data suggest that ornamental fish and their carriage water act as a reservoir for both multi-resistant bacteria and resistance genes.200920027306
193540.9998Antibiotic Susceptibility Profile and Tetracycline Resistance Genes Detection in Salmonella spp. Strains Isolated from Animals and Food. Salmonella spp. is among the leading causes of foodborne infections in humans and a large number of animals. Salmonella spp. is a pathogen involved in the dissemination of antimicrobial resistance because it can accumulate antibiotic resistance genes (ARGs). In this study, the antibiotic resistance profile to 15 antibiotics, belonging to six different classes, of 60 strains of Salmonella spp. collected from pets, farm animals, wildlife, and food in Sicily (Italy) was investigated by the Kirby-Bauer method. Given that almost 33.3% of the Salmonella spp. strains were resistant to tetracycline, Real-Time PCR analysis was applied on all the 60 strains to detect the presence of eight selected tet resistance genes. Besides, the presence of the int1 gene, related to the horizontal gene transfer among bacteria, was also investigated in all the strains by Real-Time PCR analysis. Our data showed that 56% of the isolated strains harbored one or more tet resistance genes and that these strains were most frequently isolated from animals living in close contact with humans. Concerning int1, 17 strains (28.3%) harbored this genetic element and eight of these simultaneously contained tet genes. The results of this study highlight the importance of using a molecular approach to detect resistance genetic determinants, whose spread can increase the diffusion of multidrug-resistant strains. Besides, the study of zoonotic bacteria such as Salmonella spp. which significantly contribute to ARGs dissemination should always follow a One Health approach that considers the health of humans, animals, and the environment to be closely related.202134356729
283750.9998Molecular evidence of the close relatedness of clinical, gull and wastewater isolates of quinolone-resistant Escherichia coli. Escherichia coli with reduced susceptibility to quinolones isolated from different environmental sources (urban wastewater treatment plants, n=61; hospital effluent, n=10; urban streams, n=9; gulls, n=18; birds of prey, n=17) and from hospitalised patients (n=28) were compared based on multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). The habitats with the most diversified genotypes of quinolone-resistant E. coli, corresponding to the highest genetic diversity (H'), were wastewater and gulls. In addition, genetically distinct populations were observed in clinical samples and birds of prey, suggesting the influence of the habitat or selective pressures on quinolone-resistant E. coli. The close genetic relatedness between isolates of clinical origin and from gulls and wastewater suggests the existence of potential routes of propagation between these sources. The most common sequence types were ST131 and ST10, with ST131 being highly specific to patients, although distributed in all of the other habitats except birds of prey. The prevalence of antimicrobial resistance was significantly higher in isolates from patients and gulls than from other sources (P<0.01), suggesting that the effect of selective pressures met by isolates subjected to strong human impacts. The evidence presented suggests the potential circulation of bacteria between the environmental and clinical compartments, with gulls being a relevant vector of bacteria and resistance genes.201527842875
285360.9998Antibiotic resistance and virulence genes in coliform water isolates. Widespread fecal pollution of surface water may present a major health risk and a significant pathway for dissemination of antibiotic resistance bacteria. The River Rhine is one of the longest and most important rivers in Europe and an important raw water source for drinking water production. A total of 100 coliform isolates obtained from River Rhine (Germany) were examined for their susceptibility to seven antimicrobial agents. Resistances against amoxicillin, trimethoprim/sulfamethoxazole and tetracycline were detected in 48%, 11% and 9% of isolates respectively. The antibiotic resistance could be traced back to the resistance genes bla(TEM), bla(SHV), ampC, sul1, sul2, dfrA1, tet(A) and tet(B). Whereby, the ampC gene represents a special case, because its presence is not inevitably linked to a phenotypic antibiotic resistance. Multiple antibiotics resistance was often accompanied by the occurrence of class 1 or 2 integrons. E. coli isolates belonging to phylogenetic groups A and B1 (commensal) were more predominant (57%) compared to B2 and D groups (43%) which are known to carry virulent genes. Additionally, six E. coli virulence genes were also detected. However, the prevalence of virulence genes in the E. coli isolates was low (not exceeding 4.3% per gene) and no diarrheagenic E. coli pathotypes were detected. This study demonstrates that surface water is an important reservoir of ARGs for a number of antibiotic classes such as sulfonamide, trimethoprim, beta-lactam-antibiotics and tetracycline. The occurrence of antibiotic resistance in coliform bacteria isolated from River Rhine provides evidence for the need to develop management strategies to limit the spread of antibiotic resistant bacteria in aquatic environment.201627497615
592670.9998Prevalence and Characterization of Gentamicin Resistance Genes in Escherichia coli Isolates from Beef Cattle Feces in Japan. Gentamicin is an important antibiotic for the treatment of opportunistic infections in the clinical field. Gentamicin-resistant bacteria have been detected in livestock animals and can be transmitted to humans through the food supply or direct contact. We have previously revealed that gentamicin-resistant Escherichia coli are distributed at a comparatively high rate from beef cattle in Japan, but few studies have focused on the molecular epidemiology of gentamicin-resistant bacteria. To understand these bacteria, this study examined the prevalence of various gentamicin resistance genes in gentamicin-resistant E. coli isolates from beef cattle feces. Of the 239 gentamicin-resistant E. coli isolates, the presence of the aacC2, aadB, or aac(3)-VIa genes was confirmed in 147, 84, and 8 isolates, respectively. All aac(3)-VIa-harboring isolates had an MIC value of 64 μg/mL for gentamicin and exhibited resistance to 11 antibiotic agents. An analysis of the representative aac(3)-VIa-harboring E. coli strain GC1-3-GR-4 revealed that the aac(3)-VIa gene was present on the IncA/C plasmid together with the aadA and bla(CMY) genes. Furthermore, the upstream region of the aac(3)-VIa gene contained the aadA gene and the class 1 integron-integrase gene (intI1). The aac(3)-VIa gene was detected for the first time in Japan and is expected to be able to transfer between bacteria via the IncA/C plasmid and integron. These results reveal the expansion of the distribution or diversity of gentamicin resistance genes in Japan.202235704076
558280.9998Detection and prevalence of antimicrobial resistance genes in Campylobacter spp. isolated from chickens and humans. Campylobacter spp. are common pathogenic bacteria in both veterinary and human medicine. Infections caused by Campylobacter spp. are usually treated using antibiotics. However, the injudicious use of antibiotics has been proven to spearhead the emergence of antibiotic resistance. The purpose of this study was to detect the prevalence of antibiotic resistance genes in Campylobacter spp. isolated from chickens and human clinical cases in South Africa. One hundred and sixty one isolates of Campylobacter jejuni and Campylobacter coli were collected from chickens and human clinical cases and then screened for the presence of antimicrobial resistance genes. We observed a wide distribution of the tetO gene, which confers resistance to tetracycline. The gyrA genes that are responsible quinolone resistance were also detected. Finally, our study also detected the presence of the blaOXA-61, which is associated with ampicillin resistance. There was a higher (p < 0.05) prevalence of the studied antimicrobial resistance genes in chicken faeces compared with human clinical isolates. The tetO gene was the most prevalent gene detected, which was isolated at 64% and 68% from human and chicken isolates, respectively. The presence of gyrA genes was significantly (p < 0.05) associated with quinolone resistance. In conclusion, this study demonstrated the presence of gyrA (235 bp), gyrA (270 bp), blaOXA-61 and tetO antimicrobial resistance genes in C. jejuni and C. coli isolated from chickens and human clinical cases. This indicates that Campylobacter spp. have the potential of resistance to a number of antibiotic classes.201728582978
269090.9998Characterization of Cefotaxime- and Ciprofloxacin-Resistant Commensal Escherichia coli Originating from Belgian Farm Animals Indicates High Antibiotic Resistance Transfer Rates. Food-producing animals represent one of the sources of antibiotic resistant commensal bacteria. There is an increasing awareness that these bacteria might have the potential to transfer their resistance genes to other (pathogenic) bacteria. In this study, 50 commensal Escherichia coli strains originating from food-producing animals and resistant to the "highest priority, critically important antibiotics" cefotaxime and/or ciprofloxacin, were selected for further characterization. For each strain (i) an antibiogram, (ii) the phylogenetic group, (iii) plasmid replicon type, (iv) presence and identification of integrons, and (v) antibiotic resistance transfer ratios were determined. Forty-five of these strains were resistant to 5 or more antibiotics, and 6 strains were resistant to 10 or more antibiotics. Resistance was most common to ampicillin (100%), sulfamethoxazole, ciprofloxacin (82%), trimethoprim, tetracycline (74%), cefotaxime, (70%) and ceftazidime (62%). Phylogenetic groups A (62%) and B1 (26%) were most common, followed by C (8%) and E (4%). In 43 strains, more than 1 replicon type was detected, with FII (88%), FIB (70%), and I1 (48%) being the most encountered types. Forty strains, positive for integrons, all harbored a class I integron and seven of them contained an additional class II integron. No class III integrons were detected. The antibiotic resistance transfer was assessed by liquid mating experiments. The transfer ratio, expressed as the number of transconjugants per recipient, was between 10(-5) and 10(0) for cefotaxime resistance and between 10(-7) and 10(-1) for ciprofloxacin resistance. The results of the current study prove that commensal E. coli in food-production animals can be a source of multiple resistance genes and that these bacteria can easily spread their ciprofloxacin and cefotaxime resistance.201829148895
1591100.9998Influence of agricultural practice on mobile bla genes: IncI1-bearing CTX-M, SHV, CMY and TEM in Escherichia coli from intensive farming soils. Many calls have been made to address antibiotic resistance in an environmental perspective. With this study, we showed the widespread presence of high-level antibiotic resistant isolates on a collection of non-susceptible Gram-negative bacteria (n = 232) recovered from soils. Bacteria were selected using amoxicillin, cefotaxime and imipenem, from sites representing different agricultural practices (extensive, intensive and organic). Striking levels of non-susceptibility were noticed in intensive soils for norfloxacin (74%), streptomycin (50.7%) and tetracycline (46.6%); indeed, the exposure to intensive agricultural practices constituted a risk factor for non-susceptibility to many antibiotics, multidrug resistance and production of extended-spectrum β-lactamases (ESBL). Analyses of non-susceptibility highlighted that environmental and clinical bacteria from the same species might not share the same intrinsic resistance patterns, raising concerns for therapy choices in environment-borne infections. The multiple sequence-type IncI1-driven spread of penicillinases (blaTEM-1, blaTEM-135), ESBL (blaSHV-12 and blaCTX-M-1) and plasmid-mediated AmpC β-lactamases (blaCMY-2), produced by isolates that share their molecular features with isolates from humans and animals, suggests contamination of agricultural soils. This is also the first appearance of IncI1/ST28-harbouring blaCTX-M-1, which should be monitored to prevent their establishment as successfully dispersed plasmids. This research may help disclose paths of contamination by mobile antibiotic resistance determinants and the risks for their dissemination.201626279315
5583110.9998High prevalence of antimicrobial-resistant Escherichia coli from animals at slaughter: a food safety risk. BACKGROUND: There has been concern about the increase of antimicrobial resistant bacteria and protection of animal and public health, along with food safety. In the present study, we evaluate the incidence of antimicrobial resistance among 192 strains of Escherichia coli isolated from faecal samples of healthy food-producing animals at slaughter in Portugal. RESULTS: Ninety-seven % of the pig isolates, 74% from sheep and 55% from cattle were resistant to one or more antimicrobial agents, with the resistances to ampicillin, streptomycin, tetracycline and trimethoprim-sulfamethoxazole the most common phenotype detected. Genes encoding resistance to antimicrobial agents were detected in most of the resistant isolates. Ninety-three % of the resistant isolates were included in the A or B1 phylogenetic groups, and the virulence gene fimA (alone or in association with papC or aer genes) was detected in 137 of the resistant isolates. Five isolates from pigs belonging to phylogroup B2 and D were resistant to five different antimicrobial agents. CONCLUSION: Our data shows a high percentage of antibiotic resistance in E. coli isolates from food animals, and raises important questions in the potential impact of antibiotic use in animals and the possible transmission of resistant bacteria to humans through the food chain.201322836880
5543120.9998Antimicrobial resistance in bacteria isolated from aquaculture sources in Australia. AIMS: To carry out a preliminary assessment of the occurrence of resistance to antimicrobials in bacteria that has been isolated from a variety of aquaculture species and environments in Australia. METHOD AND RESULTS: A total of 100 Gram-negative (Vibrio spp. and Aeromonas spp. predominantly) and four Gram-positive bacteria isolated from farmed fish, crustaceans and water from crab larval rearing tanks were obtained from diagnostic laboratories from different parts of Australia. All the isolates were tested for sensitivity to 19 antibiotics and Minimal Inhibitory Concentrations were determined by the agar dilution method. Plasmid DNA was isolated by the alkali lysis method. Resistance to ampicillin, amoxycillin, cephalexin and erythromycin was widespread; resistance to oxytetracycline, tetracycline, nalidixic acid and sulfonamides was common but resistance to chloramphenicol, florfenicol, ceftiofur, cephalothin, cefoperazone, oxolinic acid, gentamicin, kanamycin and trimethoprim was less common. All strains were susceptible to ciprofloxacin. Multiple resistance was also observed and 74.4% of resistant isolates had between one and ten plasmids with sizes ranging 2-51 kbp. CONCLUSIONS: No antibiotics are registered for use in aquaculture in Australia but these results suggest that there has been significant off-label use. SIGNIFICANCE AND IMPACT OF STUDY: Transfer of antibiotic resistant bacteria to humans via the food chain is a significant health concern. In comparison with studies on terrestrial food producing animals, there are fewer studies on antibiotic resistance in bacteria from aquaculture enterprises and this study provides further support to the view that there is the risk of transfer of resistant bacteria to humans from consumption of aquaculture products. From the Australian perspective, although there are no products registered for use in aquaculture, antimicrobial resistance is present in isolates from aquaculture and aquaculture environments.200616630011
5545130.9998Healthy broilers disseminate antibiotic resistance in response to tetracycline input in feed concentrates. Wide varieties of antibiotics are used in poultry farms to improve the growth and also to control the infection in broiler chicken. To identify the seriousness of the same in the poultry sector, current study has been designed to analyze the presence of tetracycline in poultry feed and also the tetracycline resistance among the bacteria released through the excreta of poultry. In the study, 27 bacteria belonging to the Escherichiacoli and Klebsiellapneumoniae. were isolated from the faecal samples collected from five different farms. Antibiotic susceptibility analysis showed 77% of E. coli and 100% of the K. pneumoniae. to be resistant to tetracycline. Further, molecular screening for tetA and tetB genes showed 85.18% of isolates to have tetA and 22.22% with tetB. The presence of tetracycline in collected feed samples was also analysed quantitatively by Liquid chromatography-mass spectrometry (LC-MS). Here, three out of five feed samples were found to be positive for tetracycline. The study showed a direct correlation between the antibiotic supplemented feed and the emergence of antimicrobial resistance among the intestinal microflora. The results of the study indicate the need for strict control over antibiotic use in animal feed to limit the rapid evolution and spread of antimicrobial resistance.202033039593
1948140.9998Identification and Characterization of Cefotaxime Resistant Bacteria in Beef Cattle. Third-generation cephalosporins are an important class of antibiotics that are widely used in treatment of serious Gram-negative bacterial infections. In this study, we report the isolation of bacteria resistant to the third-generation cephalosporin cefotaxime from cattle with no previous cefotaxime antibiotic exposure. The prevalence of cefotaxime-resistant bacteria was examined by a combination of culture based and molecular typing methods in beef cattle (n = 1341) from 8 herds located in North Central Florida. The overall prevalence of cefotaxime-resistant bacteria was 15.8% (95% CI: 13.9, 17.8), varied between farms, and ranged from 5.2% to 100%. A subset of isolates (n = 23) was further characterized for the cefotaxime minimum inhibitory concentration (MIC) and antibiotic susceptibility against 10 different antibiotics, sequencing of nine β- lactamase genes, and species identification by 16S rRNA sequencing. Most of the bacterial isolates were resistant to cefotaxime (concentrations, > 64 μg/mL) and showed high levels of multi-drug resistance. Full length 16S rRNA sequences (~1300 bp) revealed that most of the isolates were not primary human or animal pathogens; rather were more typical of commensal, soil, or other environmental origin. Six extended spectrum β-lactamase (ESBL) genes identical to those in clinical human isolates were identified. Our study highlights the potential for carriage of cefotaxime resistance (including "human" ESBL genes) by the bacterial flora of food animals with no history of cefotaxime antibiotic exposure. A better understanding of the origin and transmission of resistance genes in these pre-harvest settings will be critical to development of strategies to prevent the spread of antimicrobial resistant microorganisms to hospitals and communities.201627642751
5588150.9998Phenotypic and genotypic analyses of antimicrobial resistant bacteria in livestock in Uganda. Antimicrobial resistant bacteria (ARB) in livestock are a global public health concern, not only because they prolong infectious diseases but also they can be transferred from animals to humans via the food chain. Here, we studied ARB in livestock at commercial and subsistence farms (n = 13) in Wakiso and Mpigi districts, Uganda. We enquired from the farmers about the type and the purpose of antimicrobial agents they have used to treat their livestock. After collecting faeces, we isolated antimicrobial resistant Escherichia coli from livestock faeces (n = 134) as an indicator bacterium. These strains showed resistance to ampicillin (44.8%), tetracycline (97.0%), and sulfamethoxazole-trimethoprim (56.7%). The frequency of ampicillin-resistance was significantly correlated with the usage of penicillins to livestock in the farms (p = 0.04). The metagenomics data detected 911 antimicrobial resistant genes that were classified into 16 categories. Genes for multidrug efflux pumps were the most prevalent category in all except in one sample. Interestingly, the genes encoding third-generation cephalosporins (bla(CTX-M) ), carbapenems (bla(ACT) ), and colistin (arnA) were detected by metagenomics analysis although these phenotypes were not detected in our E. coli strains. Our results suggest that the emergence and transmission of cephalosporin, carbapenem, and/or colistin-resistant bacteria among livestock can occur in future if these antimicrobial agents are used.201930260584
5727160.9998Genetic mechanisms of antimicrobial resistance identified in Salmonella enterica, Escherichia coli, and Enteroccocus spp. isolated from U.S. food animals. The prevalence of antimicrobial resistance (AR) in bacteria isolated from U.S. food animals has increased over the last several decades as have concerns of AR foodborne zoonotic human infections. Resistance mechanisms identified in U.S. animal isolates of Salmonella enterica included resistance to aminoglycosides (e.g., alleles of aacC, aadA, aadB, ant, aphA, and StrAB), β-lactams (e.g., bla CMY-2, TEM-1, PSE-1), chloramphenicol (e.g., floR, cmlA, cat1, cat2), folate pathway inhibitors (e.g., alleles of sul and dfr), and tetracycline [e.g., alleles of tet(A), (B), (C), (D), (G), and tetR]. In the U.S., multi-drug resistance (MDR) mechanisms in Salmonella animal isolates were associated with integrons, or mobile genetic elements (MGEs) such as IncA/C plasmids which can be transferred among bacteria. It is thought that AR Salmonella originates in food animals and is transmitted through food to humans. However, some AR Salmonella isolated from humans in the U.S. have different AR elements than those isolated from food animals, suggesting a different etiology for some AR human infections. The AR mechanisms identified in isolates from outside the U.S. are also predominantly different. For example the extended spectrum β-lactamases (ESBLs) are found in human and animal isolates globally; however, in the U.S., ESBLs thus far have only been found in human and not food animal isolates. Commensal bacteria in animals including Escherichia coli and Enterococcus spp. may be reservoirs for AR mechanisms. Many of the AR genes and MGEs found in E. coli isolated from U.S. animals are similar to those found in Salmonella. Enterococcus spp. isolated from animals frequently carry MGEs with AR genes, including resistances to aminoglycosides (e.g., alleles of aac, ant, and aph), macrolides [e.g., erm(A), erm(B), and msrC], and tetracyclines [e.g., tet(K), (L), (M), (O), (S)]. Continuing investigations are required to help understand and mitigate the impact of AR bacteria on human and animal health.201323734150
2976170.9998Phenotypic and Genotypic Antimicrobial Resistance in Non-O157 Shiga Toxin-Producing Escherichia coli Isolated From Cattle and Swine in Chile. Non-O157 Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen that causes bloody diarrhea and hemolytic-uremic syndrome in humans, and a major cause of foodborne disease. Despite antibiotic treatment of STEC infections in humans is not recommended, the presence of antimicrobial-resistant bacteria in animals and food constitutes a risk to public health, as the pool of genes from which pathogenic bacteria can acquire antibiotic resistance has increased. Additionally, in Chile there is no information on the antimicrobial resistance of this pathogen in livestock. Thus, the aim of this study was to characterize the phenotypic and genotypic antimicrobial resistance of STEC strains isolated from cattle and swine in the Metropolitan region, Chile, to contribute relevant data to antimicrobial resistance surveillance programs at national and international level. We assessed the minimal inhibitory concentration of 18 antimicrobials, and the distribution of 12 antimicrobial resistance genes and class 1 and 2 integrons in 54 STEC strains. All strains were phenotypically resistant to at least one antimicrobial drug, with a 100% of resistance to cefalexin, followed by colistin (81.5%), chloramphenicol (14.8%), ampicillin and enrofloxacin (5.6% each), doxycycline (3.7%), and cefovecin (1.9%). Most detected antibiotic resistance genes were dfrA1 and tetA (100%), followed by tetB (94.4%), bla (TEM-1) (90.7%), aac(6)-Ib (88.9%), bla (AmpC) (81.5%), cat1 (61.1%), and aac(3)-IIa (11.1%). Integrons were detected only in strains of swine origin. Therefore, this study provides further evidence that non-O157 STEC strains present in livestock in the Metropolitan region of Chile exhibit phenotypic and genotypic resistance against antimicrobials that are critical for human and veterinary medicine, representing a major threat for public health. Additionally, these strains could have a competitive advantage in the presence of antimicrobial selective pressure, leading to an increase in food contamination. This study highlights the need for coordinated local and global actions regarding the use of antimicrobials in animal food production.202032754621
2854180.9998Occurrence of antibiotic resistance genes in culturable bacteria isolated from Turkish trout farms and their local aquatic environment. Antibiotic resistance and presence of the resistance genes were investigated in the bacteria isolated from water, sediment, and fish in trout farms. A total of 9 bacterial species, particularly Escherichia coli, were isolated from the water and sediment samples, and 12 species were isolated from fish. The antimicrobial test indicated the highest resistance against sulfamethoxazole and ampicillin in coliform bacteria, and against sulfamethoxazole, imipenem, and aztreonam in known pathogenic bacteria isolated from fish. The most effective antibiotics were rifampicin, chloramphenicol, and tetracycline. The multiple antibiotic resistance index was above the critical limit for almost all of the bacteria isolated. The most common antibiotic resistance gene was ampC, followed by tetA, sul2, blaCTX-M1, and blaTEM in the coliform bacteria. At least one resistance gene was found in 70.8% of the bacteria, and 66.6% of the bacteria had 2 or more resistance genes. Approximately 36.54% of the bacteria that contain plasmids were able to transfer them to other bacteria. The plasmid-mediated transferable resistance genes were ampC, blaCTX-M1, tetA, sul2, and blaTEM. These results indicate that the aquatic environment could play an important role in the development of antibiotic resistance and the dissemination of resistance genes among bacteria.201525993887
2871190.9998Antimicrobial resistance in generic Escherichia coli isolates from wild small mammals living in swine farm, residential, landfill, and natural environments in southern Ontario, Canada. To assess the impacts of different types of human activity on the development of resistant bacteria in the feces of wild small mammals, we compared the prevalences and patterns of antimicrobial resistance and resistance genes in generic Escherichia coli and Salmonella enterica isolates from fecal samples collected from wild small mammals living in four environments: swine farms, residential areas, landfills, and natural habitats. Resistance to antimicrobials was observed in E. coli isolates from animals in all environments: 25/52 (48%) animals trapped at swine farms, 6/69 (9%) animals trapped in residential areas, 3/20 (15%) animals trapped at landfills, and 1/22 (5%) animals trapped in natural habitats. Animals trapped on farms were significantly more likely to carry E. coli isolates with resistance to tetracycline, ampicillin, sulfisoxazole, and streptomycin than animals trapped in residential areas. The resistance genes sul2, aadA, and tet(A) were significantly more likely to be detected in E. coli isolates from animals trapped on farms than from those trapped in residential areas. Three S. enterica serotypes (Give, Typhimurium, and Newport) were recovered from the feces of 4/302 (1%) wild small mammals. All Salmonella isolates were pansusceptible. Our results show that swine farm origin is significantly associated with the presence of resistant bacteria and resistance genes in wild small mammals in southern Ontario, Canada. However, resistant fecal bacteria were found in small mammals living in all environments studied, indicating that environmental exposure to antimicrobials, antimicrobial residues, resistant bacteria, or resistance genes is widespread.201121131524