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1.
Quinolone resistance is studied and reported increasingly in isolates from humans, food-producing animals and companion animals. Resistance can be caused by chromosomal mutations in topoisomerase genes, plasmid-mediated resistance genes, and active transport through efflux pumps. Cross sectional data on quinolone resistance mechanisms in non-pathogenic bacteria from healthy veal calves is limited. The purpose of this study was to determine the prevalence and characteristics of quinolone resistance mechanisms in Escherichia coli isolates from veal calves, after more than 20 years of quinolone usage in veal calves. MIC values were determined for all isolates collected as part of a national surveillance program on antimicrobial resistance in commensal bacteria in food-producing animals in The Netherlands. From the strains collected from veal calves in 2007 (n=175) all isolates with ciprofloxacin MIC ≥ 0.125 mg/L (n=25) were selected for this study, and screened for the presence of known quinolone resistance determinants. In this selection only chromosomal mutations in the topoisomerase type II and IV genes were detected. The number of mutations found per isolate correlated with an increasing ciprofloxacin MIC. No plasmid-mediated quinolone resistance genes were found. The contribution of efflux pumps varied from no contribution to a 16-fold increase in susceptibility. No correlation was found with the presence of resistance genes of other antimicrobial classes, even though all quinolone non-wild type isolates were resistant to 3 or more classes of antibiotics other than quinolones. Over twenty years of quinolone usage in veal calves in The Netherlands did not result in a widespread occurrence of plasmid-mediated quinolone resistance, limiting the transmission of quinolone resistance to clonal distribution.  相似文献   

2.
Bacteria with antimicrobial resistance can be transferred from animals to humans and may compromise antimicrobial treatment in case of infection. To determine the antimicrobial resistance situation in bacteria from Swiss veal calves, faecal samples from 500 randomly selected calves originating from 129 farms were collected at four big slaughterhouses. Samples were cultured for Escherichia coli, Enterococcus sp. and Campylobacter sp. and isolated strains were tested for antimicrobial susceptibility to selected antimicrobial agents by the minimal inhibitory concentration technique using the broth microdilution method. From 100 farms, data on farm management, animal husbandry and antimicrobial treatments of the calves were collected by questionnaire. Risk factors associated with antimicrobial resistance were identified by logistic regression. In total, 467 E. coli, 413 Enterococcus sp. and 202 Campylobacter sp. were isolated. Of those, 68.7%, 98.7% and 67.8%, respectively, were resistant to at least one of the tested antimicrobial agents. Resistance was mainly observed to antimicrobials frequently used in farm animals. Prevalence of resistance to antimicrobials important for human treatment was generally low. However, a rather high number of quinupristin/dalfopristin-resistant Enterococcus faecium and ciprofloxacin-resistant Campylobacter sp. were detected. External calf purchase, large finishing groups, feeding of milk by-products and administration of antimicrobials through feed upon arrival of the animals on the farm significantly increased the risk of antimicrobial resistance at farm level. Participation in a quality assurance programme and injection of a macrolide upon arrival of the animals on the farm had a protective effect. The present study showed that veal calves may serve as a reservoir for resistant bacteria. To ensure food safety, veal calves should be included in the national monitoring programme for antimicrobial resistance in farm animals. By improving farm management and calf husbandry the prevalence of resistance may be reduced.  相似文献   

3.
OBJECTIVE: To compare antimicrobial susceptibility patterns of Escherichia coli isolates cultured from fecal samples from cows and calves on dairy farms that used organic (ie, no or severely limited antimicrobial use) versus conventional production methods. DESIGN: Cross-sectional study. SAMPLE POPULATION: Fecal samples from 10 cows and 10 calves on each of 30 organic dairy farms and 30 neighboring conventional dairy farms in Wisconsin. PROCEDURE: E. coli isolates obtained from the fecal samples were tested for susceptibility to 17 antimicrobials by means of a microbroth dilution test. Prevalence of antimicrobial resistance was compared between organic and conventional dairy farms. RESULTS: E. coli was isolated from 1,121 (94%) fecal samples. Farm type (organic vs conventional) and animal age (cow vs calf) were significantly associated with odds that E. coli isolates would be resistant to various antimicrobials. After controlling for age, logistic regression analyses indicated that isolates from conventional dairy farms had significantly higher rates of resistance to ampicillin, streptomycin, kanamycin, gentamicin, chloramphenicol, tetracycline, and sulfamethoxazole than did isolates from organic dairy farms. However, no significant differences were detected for the 10 other antimicrobials that were tested. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that compared with isolates from conventional dairy farms, E. coli isolates from organic dairy herds have significantly lower prevalences of resistance to 7 antimicrobials; however, prevalence of resistance was not significantly different for 10 other antimicrobials. Resistance was more common for isolates from calves than for isolates from adult dairy cows.  相似文献   

4.
To investigate the prevalence and molecular characterization of class Ⅰ integron in Escherichia coli isolated from beef cattle, and analyze the relationship between integron and antimicrobial resistance, susceptibilities to 11 antimicrobials were conducted on 92 isolates, the presence and characterization of class Ⅰ integrons and inserted gene cassettes were performed using PCR combined with sequencing analysis. The results showed that 29 isolates had been detected positive for class Ⅰ integron integrase gene (intⅠ1) among 92 isolates, and aadA1 and dfrA17＋aadA5 were the most prevalent gene cassette arrays detected. The resistance rates of 92 isolates to ampicillin, streptomycin, sulfisoxazole and tetracycline were all more than 45.0%. As revealed by analyzing the association between resistance phenotypes and class Ⅰ integron, isolates that contained the class Ⅰ integron were significantly highly resistant to ampicillin, chloramphenicol, streptomycin, sulfisoxazole and sulfamethoxazole-trimethoprim (P<0.05), but not to quinolones and amoxicillin/clavulanic acid. The conclusion was that E.coli isolated from beef cattle were seriously resistant to antimicrobials,and integron/cassettes widely existed. The presence of integrons and the association of antimicrobial resistance determinants with transferable elements might play a crucial role in the dissemination of antibiotic resistance among E.coli. Data reported here clearly emphasized the need for a stricter application of antimicrobials restriction policies in feedlot setting.  相似文献   

5.
A randomized, controlled, blinded clinical trial was performed at a research feedlot in western Canada. Auction-market-derived steers (n = 288) were randomly assigned to 1 of 3 treatments: 1) no antimicrobials on arrival; 2) oxytetracycline in the starter ration for 14 d; and 3) long-acting oxytetracycline subcutaneously on day 0. Minimal inhibitory concentrations of 7 antimicrobials were determined for 3 generic fecal E. coli isolates per animal on arrival and throughout the feeding period. There was a low prevalence of antimicrobial resistance in generic E. coli isolates from calves on arrival. There were increased proportions of cattle with resistant E. coli isolates early in the feeding period among calves in groups 2 and 3. Individual animal treatments were not associated with increased proportions of cattle with resistant E. coli isolates preslaughter. There was no difference in the proportion of animals with E. coli isolates resistant to tetracycline between the treatment groups preslaughter. However, there were significantly more animals with tetracycline resistant isolates of E. coli preslaughter than at arrival.  相似文献   

6.
An observational study was conducted of chicken and turkey flocks slaughtered at federal processing plants in the province of Quebec, Canada. The objectives were to estimate prevalence of drug use at hatchery and on farm and to identify antimicrobial resistance (AMR) in cecal Escherichia coli and Enterococcus spp. isolates and factors associated with AMR. Eighty-two chicken flocks and 59 turkey flocks were sampled. At the hatchery, the most used antimicrobial was ceftiofur in chickens (76% of flocks) and spectinomycin in turkeys (42% of flocks). Virginiamycin was the antimicrobial most frequently added to the feed in both chicken and turkey flocks. At least 1 E. coli isolate resistant to third-generation cephalosporins was present in all chicken flocks and in a third of turkey flocks. Resistance to tetracycline, streptomycin, and sulfisoxazole was detected in > 90% of flocks for E. coli isolates. Antimicrobial resistance (AMR) was observed to bacitracin, erythromycin, lincomycin, quinupristin-dalfopristin, and tetracycline in both chicken and turkey flocks for Enterococcus spp. isolates. No resistance to vancomycin was observed. The use of ceftiofur at hatchery was significantly associated with the proportion of ceftiofur-resistant E. coli isolates in chicken flocks. In turkey flocks, ceftiofur resistance was more frequent when turkeys were placed on litter previously used by chickens. Associations between drug use and resistance were observed with tetracycline (turkey) in E. coli isolates and with bacitracin (chicken and turkey), gentamicin (turkey), and tylosin (chicken) in Enterococcus spp. isolates. Further studies are needed to provide producers and veterinarians with alternative management practices and tools in order to reduce the use of antimicrobial feed additives in poultry.  相似文献   

7.
Rectal smears of calves, cows and young bulls, as well as cloacal smears of house sparrows (Passer domesticus), from farms at the villages of Sumice and Troskotovice, Czech Republic, were examined for E. coli resistant to 12 antimicrobials. The resistant isolates were tested for antimicrobial-resistance genes and integrons. Totals of 40% (n=183), 3% (n=95), 0% (n=33), and 9% (n=54) of Escherichia coli isolates from calves, cows, young bulls and house sparrows, respectively, were antimicrobial resistant. The following genes were identified in cattle E. coli isolates: tetA, tetB (isolates resistant to tetracycline), bla(TEM) (beta-lactams), strA, aadA (streptomycin), sul1, sul2 (sulphonamides), and cat, floR (chloramphenicol). Seven of 16 antimicrobial-resistant calf isolates from the Sumice farm possessed class 1 integrons with the aadA1 gene cassette integrated, 1 kb in size. On the Troskotovice farm, eight of 57 antimicrobial-resistant calf isolates possessed class 1 integrons. Integrons of 1.5kb with the dhfr1- aadA1 gene cassette were found in four isolates, followed by a 1kb integron with the aadA1 gene found in three isolates, and a 1.7kb integron with the dhfr17-aadA5 gene cassette and the phenotype ASSuTSxtNaCipCCfG. The prevalence of resistant E. coli in calves compared to adult cattle was much higher and probably was influenced by oral antimicrobial usage in calves, feeding with milk and colostrum from treated cows, as well as mechanisms unrelated to antimicrobial drug selection. Although house sparrows lived together with the cattle and came into contact with cattle waste on the farm, they were not infected by resistant E. coli isolates with the same characteristics as those found in cattle.  相似文献   

8.
The prevalence of resistant bacteria in food products in Iceland is unknown, and little is known of the prevalence in production animals. The aim of this study was to investigate the prevalence and genetic relatedness of antimicrobial‐resistant Escherichia coli from healthy pigs and broiler chicken, pork, broiler meat, slaughterhouse personnel and outpatients in Iceland. A total of 419 E. coli isolates were tested for antimicrobial susceptibility using a microbroth dilution method (VetMIC), and resistant strains were compared using pulsed‐field gel electrophoresis (PFGE). All samples were screened for enrofloxacin‐resistant strains with selective agar plates. The resistance rates among E. coli isolates were moderate to high from caecal and meat samples of pigs (54.1% and 28%), broilers (33.6% and 52%) and slaughterhouse personnel (39.1%), whereas isolates from outpatients showed moderate resistance rates (23.1%). Of notice was resistance to quinolones (minimum inhibitory concentrations: nalidixic acid ≥ 32, ciprofloxacin ≥ 0.12 and enrofloxacin ≥ 0.5), particularly among broiler and broiler meat isolates (18.2% and 36%), as there is no known antimicrobial selection pressure in the broiler production in Iceland. The majority (78.6%) of the resistant E. coli isolates was genotypically different, based on PFGE fingerprint analyses and clustering was limited. However, the same resistance pattern and pulsotype were found among isolates from broiler meat and a slaughterhouse worker, indicating spread of antimicrobial‐resistant E. coli from animals to humans. Diverse resistance patterns and pulsotypes suggest the presence of a large population of resistant E. coli in production animals in Iceland. This study gives baseline information on the prevalence of antimicrobial‐resistant E. coli from production animals, and their food products in Iceland and the moderate to high resistance rates emphasize the need for continuing surveillance. Further studies on the origin of the resistant strains and the genetic relatedness of strains of different origin are needed.  相似文献   

9.
为了解畜禽源大肠杆菌的耐药状况,2011—2012年从患病和健康食品动物中分离鉴定大肠杆菌935株,包括健康猪源606株、患病猪源114株、患病鸡源51株、患病水禽源(鸭和鹅)164株。试验采用琼脂稀释法测定了不同动物来源的大肠杆菌对15种抗菌药物的敏感性。结果发现,大肠杆菌耐药严重,对大部分药物的耐药率超过70.0%,其中氨苄西林、复方新诺明和四环素的耐药率均达到了80.0%以上;仅对头孢西丁、黏菌素和阿米卡星较敏感,但患病水禽源大肠杆菌对阿米卡星的耐药率达到了52.4%,明显高于其他动物。健康畜禽源大肠杆菌对多数抗菌药的耐药率低于患病畜禽源大肠杆菌,表明抗菌药物的使用增加了病原菌对第3代头孢类药物和氟喹诺酮类药物的耐药率,势必增加临床治疗难度。  相似文献   

10.
The resistance patterns of Campylobacter spp. isolated from retail broiler chicken meat originating either from Estonia, Lithuania or Latvia collected in Estonia were determined. Additionally, in collaboration with the laboratories of several Estonian hospitals, antimicrobial susceptibility patterns were determined for Campylobacter isolates from patients with severe Campylobacter enteric infections. The isolates were identified at the species level by the PCR method. Respectively, 88.8% of the isolates were C. jejuni, and 11.2% were C. coli. In total, 126 Campylobacter isolates of broiler chicken meat and human origin were tested for minimal inhibitory concentrations (MICs) with the broth microdilution VetMICTH method (National Veterinary Institute; Uppsala, Sweden) for a total of six antimicrobials. Resistance to one or more antimicrobials was detected in 62 (63.3%) of Campylobacter broiler chicken meat isolates and in 20 (71.4%) of human‐origin isolates. Large proportions of the broiler chicken meat isolates were resistant to ciprofloxacin (60.2%). Multidrug resistance (i.e. to three or more unrelated antimicrobials) was detected in five (5.1%) C. jejuni isolates. Among the human isolates, 20 (71.4%) were resistant to fluoroquinolones, and two (7.1%) C. jejuni isolates exhibited multidrug resistance. The chicken meat isolates of Estonian origin were the most susceptible. However, a high proportion of fluoroquinolone‐resistant C. jejuni isolates were found in Latvian and Lithuanian products. The results of this study indicate that the problems caused by the inappropriate use of antimicrobials extend beyond the country in which a food originates; therefore, both domestic and international interventions and agreements are required to implement common policies on antimicrobial usage and to minimize the emergence of Campylobacter drug resistance.  相似文献   

11.
本试验旨在了解屠宰前鸡、猪源食品动物体内大肠杆菌耐药情况,分析潜在的食品安全问题。从广州市畜禽交易市场随机采集待屠宰鸡和猪的粪便样品,分离鉴定大肠杆菌,并采用琼脂稀释法检测大肠杆菌对15种抗菌药物的敏感性。结果显示,从658份猪源样品和133份鸡源样品中共分离鉴定出731株大肠杆菌,其中猪源606株,鸡源125株。药敏试验结果显示,731株大肠杆菌均表现出不同程度的耐药,耐药谱广且多重耐药现象严重。对复方新诺明和四环素的耐药率为90.0%以上,仅对头孢西丁、黏菌素和阿米卡星较敏感(耐药率均低于3%)。鸡源大肠杆菌对头孢噻肟、头孢曲松、新霉素、阿米卡星、萘啶酸和环丙沙星的耐药率显著高于猪源大肠杆菌(P＜0.05)。鸡源大肠杆菌中3耐及3耐以上的菌株占97.60%,猪源大肠杆菌占94.72%。结果表明,屠宰前畜禽体内大肠杆菌对临床常用抗菌药物的耐药性非常严重,以多重耐药为主,且耐药谱丰富多样。提示屠宰前畜禽携带的耐药菌对食品安全和人类健康存在较大的安全隐患。  相似文献   

12.
Distillers grains, a coproduct of ethanol production from cereal grains, are composed principally of the bran, protein, and germ fractions and are commonly supplemented in ruminant diets. The objective of this study was to assess the effect of feeding wet distillers grains with solubles (WDGS) and monensin and tylosin on the prevalence and antimicrobial susceptibilities of fecal foodborne and commensal bacteria in feedlot cattle. Cattle were fed 0 or 25% WDGS in steam-flaked corn-based diets with the addition of no antimicrobials, monensin, or monensin and tylosin. Fecal samples were collected from each animal (n = 370) on d 122 and 136 of the 150-d finishing period and cultured for Escherichia coli O157. Fecal samples were also pooled by pen (n = 54) and cultured for E. coli O157, Salmonella, commensal E. coli, and Enterococcus species. Antimicrobial resistance was assessed by determining antimicrobial susceptibilities of pen bacterial isolates and quantifying antimicrobial resistance genes in fecal samples by real-time PCR. Individual animal prevalence of E. coli O157 in feces collected from cattle fed WDGS was greater (P < 0.001) compared with cattle not fed WDGS on d 122 but not on d 136. There were no treatment effects on the prevalence of E. coli O157 or Salmonella spp. in pooled fecal samples. Antimicrobial susceptibility results showed Enterococcus isolates from cattle fed monensin or monensin and tylosin had greater levels of resistance toward macrolides (P = 0.01). There was no effect of diet or antimicrobials on concentrations of 2 antimicrobial resistance genes, ermB or tetM, in fecal samples. Results from this study indicate that WDGS may have an effect on the prevalence of E. coli O157 and the concentration of selected antimicrobial resistance genes, but does not appear to affect antimicrobial susceptibility patterns in Enterococcus and generic E. coli isolates.  相似文献   

13.
This paper reviews common therapeutic applications of antimicrobials in broiler chicken production in relation to Canadian guidelines, surveillance data, and emerging public health concerns about antimicrobial use (AMU). Escherichia coli, Clostridium perfringens, and Staphylococcus spp., were reviewed because of their animal health and economic significance. Enterococcus cecorum and Salmonella were included because of their importance in antimicrobial resistance (AMR) surveillance. This review identified that i) antimicrobials are available in Canada to treat infections by these agents, but may be through over the counter or extra-label use, ii) prevalence rates for these diseases are unknown, iii) antimicrobial use estimates in broilers are lacking, and iv) AMR has emerged in clinical isolates, though data are very sparse. This review highlights the need for surveillance of AMU and AMR in broiler chickens in Canada.  相似文献   

14.
The occurrence of antimicrobial resistance in generic Escherichia coli can serve as an indicator of the pool of resistance genes potentially available for transfer to pathogenic organisms. This study was conducted on 29 volunteer beef farms in Ontario to describe the prevalence and patterns of antimicrobial resistance in E. coli, and to describe changes in the prevalence of resistance during the feedlot stage of production. From the pooled fecal samples on 28 of the 29 farms, 31% of isolates from feedlots (n = 993) and 12% of isolates from cow-calf farms (n = 807) were resistant to one or more of 16 antimicrobials tested. No isolates were resistant to ceftriaxone, ciprofloxacin, gentamicin, or nalidixic acid, and < 1% of the pooled isolates were resistant to ceftiofur. Two percent of both feedlot and cow-calf isolates were resistant to > or = 5 antimicrobials. Cow-calf farms were at significantly lower risk than feedlots for having E. coli isolates that were resistant to streptomycin, sulfamethoxazole, and tetracycline. On average, the prevalence of sulfamethoxazole resistant E. coli isolates was significantly higher in calves than in cows. No resistance was observed to ceftriaxone or ciprofloxacin among isolates (n = 1265) obtained from individually sampled feedlot animals on 2 farms. Less than 1% of these isolates were resistant to gentamicin, nalidixic acid, and ceftiofur. From the individually sampled feedlot animals, resistance to streptomycin (on 1 farm), sulfamethoxazole, and tetracycline increased significantly from arrival to mid-point during the feeding period, and these levels persisted until market-readiness.  相似文献   

15.
A prospective observational study was carried out to examine antimicrobial resistance patterns of fecal Escherichia coli isolates of calves on arrival at the feedlot, and then evaluate the associations between the total volume of antimicrobial used for disease treatment and changes in antimicrobial resistance, during the feeding period. No macrolides or tetracyclines were administered in the feed during this study. On arrival, at the animal level, all 3 isolates obtained from 36.6% [95% confidence interval (CI): 29.0 to 44.8] of all cattle sampled (n = 153), were susceptible to all antimicrobials, while 5.9% (95% CI: 2.7 to 10.9) of cattle had at least 1 isolate that was resistant to ≥ 3 antimicrobials out of the 7 antimicrobials tested. The most frequent antimicrobials for which resistance was observed were sulphamethoxazole, ampicillin, and tetracycline where, of all cattle, 44.4% (95% CI: 36.4 to 52.7), 20.3% (95% CI: 14.2 to 27.5), and 17.7% (95% CI: 12.0 to 24.6), respectively had at least 1 resistant isolate. All cattle received antimicrobial metaphylaxis on arrival at the feedlot. Antimicrobial use was described for a cohort of 95 cattle. Antimicrobials were given to 42 of the 95 cattle during the feeding period, to treat disease. Amongst the 42 treated cattle, there were a total of 133 animal daily doses (ADDFeedlot), where 1 ADDFeedlot represented 1 day of antimicrobial treatment received by a feedlot animal at the approved dose. Only 1 ADDFeedlot was given in the 100 days immediately prior to slaughter. There were no associations found between antimicrobial use and antimicrobial resistance in this study.  相似文献   

16.
Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is highly prevalent in pork and veal production chains. In this study, we used data from a cross-sectional survey on 2151 calves from 102 veal calf farms to identify potential risk factors, with the goal of reducing MRSA prevalence by developing intervention strategies. Overall, calves from rose veal farms had a lower risk of LA-MRSA carriage than calves from white veal farms. Data were analysed separately for white and rose veal calves, because management systems of the two production chains were largely different. Group treatment with antimicrobials appeared to be a risk factor for MRSA carriage in white veal calves in univariate analyses, but was not included in the final multiple regression model that included age of the calves and rodent control. Number of start treatment days was positively associated with LA-MRSA carriage in rose veal calves, and was the only risk factor selected for the final multiple regression model for this group. Interpretation of the results from this cross-sectional study is complicated by the strong correlation between antimicrobial use, LA-MRSA carriage and age of the calves. Other age-related factors may be more influential. However, taken together these findings emphasize the need for prudent use of antimicrobials, and point to improvement of farm hygiene as a control measure.  相似文献   

17.
The aims of the study were to determine the prevalence of enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) and other Shiga toxin-producing E. coli (STEC) in feces of white veal calves in an operation in Ontario, to evaluate exposure of the calves to EHEC O157, and to investigate the milk replacer diet and antimicrobial resistance as factors that might influence the prevalence of EHEC O157. Feces from three cohorts of 20-21 calves were collected weekly for 20 weeks and processed for isolation of EHEC O157:H7 and detection of STEC by an ELISA. Exposure to EHEC O157 was also investigated by measuring IgG and IgM antibodies to the O157 lipopolysaccharide (O157 Ab) in sera by ELISA. The prevalences of EHEC O157 were 0.17% of 1151 fecal samples and 3.2% of 62 calves, and for STEC were 68% of 1005 fecal samples and 100% of 62 calves. Seroconversion to active IgG and IgM O157 Ab responses in some calves was not associated with isolation of EHEC O157. The milk replacer contained low levels of antibodies to EHEC antigens and without antimicrobial drugs, it did not inhibit the growth of EHEC O157 in vitro. Two E. coli O157:H7 that were isolated were totally drug sensitive whereas 60 commensal E. coli isolates that were examined were highly resistant. Antibodies in milk replacer that might be protective in vivo, and susceptibility to antimicrobial agents in the milk replacer may contribute to the low prevalence of EHEC O157 in white veal calves.  相似文献   

18.
Antibiotic resistance was investigated in Escherichia Coli isolated from beef, veal, lamb and pork at retail level. A total of 100 samples from each meat species was examined. About 16% of the 400 samples were contaminated with resistant E.coli. Significantly more E.coli isolates from pork were drug-resistant than isolates from other meats (P<0.01). About 7% of the combined beef, veal, and lamb E.coli isolates were resistant to two or more antibiotics compared to about 40.0% of the pork isolates (P<0.01) Transfer of resistance was observed for 39.2% of multiple resistant isolates. The results presented form a base for future monitoring of the presence of antibiotic-resistant coliforms on meat suitable for human consumption.  相似文献   

19.
The objectives of this study were to investigate the associations between antimicrobial resistance patterns in generic Escherichia coli and Salmonella spp. isolates recovered from identical pen pooled fecal samples, and to evaluate potential clustering of multiple isolates of these organisms within identical fecal samples. Up to 5 generic E. coli (n = 922 isolates) and Salmonella spp. (n = 922 isolates) isolates were obtained from each of 188 pen pooled fecal samples that had been collected from 45 finishing swine farms in Alberta in 2000, and tested for susceptibility to 15 antimicrobials. No isolates of either organism were resistant to 3rd generation cephalosporins or fluoroquinolones, which in Canada are considered antimicrobials of very high importance to human health. Approximately twice as many generic E. coli isolates as Salmonella spp. isolates were resistant to at least 1 antimicrobial. In addition, E. coli isolates showed more multidrug-resistance patterns. No significant association was observed between the resistance phenotypes of Salmonella spp. and E. coli at the fecal sample level. More clustering at the sample level was observed for proportions of antimicrobial resistance (AMR) in Salmonella spp. isolates than E. coli indicating that in future studies it might be sufficient to test fewer than 5 Salmonella spp. isolates per sample.  相似文献   

20.
The objective of this study was to describe antimicrobial resistance patterns in fecal generic Escherichia coli obtained from calves in western Canadian cow-calf herds. Susceptibility testing was completed on 1677 isolates obtained from 480 beef calves in 91 herds in the spring, and from 1187 isolates obtained from 394 calves in 45 herds in the fall of 2002. Resistance was rare to antimicrobials classified as being of very high importance to human health. Isolates were most commonly resistant to tetracycline, sulphamethoxazole, and streptomycin. Resistance to at least one antimicrobial was identified in 48.8% of the isolates collected in the spring, and 7.0% of those collected in the fall. Spring or fall calf resistance status was not associated with calf gender, breed, age of the dam, or if the calf was treated before sample collection. Calves < or = 3 days of age were less likely to be resistance positive than calves > 10 days of age.  相似文献   

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