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1.
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   

2.
OBJECTIVE: To determine and compare levels and patterns of antimicrobial resistance among Escherichia coli isolated from pigs on farms that did not use antimicrobial agents versus pigs produced under conventional methods. DESIGN: Cross-sectional study. Sample Population-35 antimicrobial-free and 60 conventional swine farms. PROCEDURES: Farms were visited once, and fecal samples were collected from 15 finisher pigs if available. One E coli isolate from each sample was tested for susceptibility pattern to 14 antimicrobial agents by use of microbroth dilution. RESULTS: E coli isolates were recovered from 1,381 (97.1%) of 1,422 fecal samples. Herd size was significantly larger for conventional swine farms. Resistance to ceftriaxone, ciprofloxacin, or nalidixic acid was not observed on any of the 95 farms. Three isolates from 2 conventional farms were resistant to ceftiofur. Conventional farms had significantly higher levels of resistance to ampicillin, sulfamethoxazole, tetracycline, and chloramphenicol, compared with antimicrobial-free farms. Fourteen percent of E coli isolates were susceptible or had intermediate resistance to all the tested antimicrobial agents. The 3 most frequent patterns of multiple resistance were streptomycin-tetracycline, sulfamethoxazole-tetracycline, and kanamycin-streptomycin-sulfamethoxazole-tetracycline. CONCLUSIONS AND CLINICAL RELEVANCE: Cessation of antimicrobial use did not appear to result in an immediate reduction in antimicrobial resistance in swine farms. Prospective studies of long-term antimicrobial usage and cessation are needed to estimate the extent to which food animal production may be contributing to antimicrobial drug resistance and might provide a direct measure of the rates of reversibility of antimicrobial drug resistance that might be achieved by curtailing antimicrobial usage.  相似文献   

3.
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   

4.
AIM: To determine the resistance to antibiotics among the indictor bacteria, Escherichia coli and Enterococcus spp, isolated from the faeces of healthy pigs on three conventional pig farms and one organic farm in the North Island of New Zealand. METHODS: Faecal samples, collected at intervals between March and October 2001, were plated onto MacConkey agar and Slanetz-Bartley agar and examined after 1-3 days incubation for colonies resembling E. coli and Enterococcus spp, respectively. Typical colonies were subcultured for further identification and storage. The isolates were tested for antibiotic resistance, using disc diffusion, to ampicillin, gentamicin, streptomycin, and tetracycline. Escherichia coli isolates were also tested for resistance to ciprofloxacin, cotrimoxazole and neomycin. Enterococcus spp isolates were also tested for resistance to vancomycin, erythromycin and virginiamycin. RESULTS: A total of 296 E. coli and 273 Enterococcus spp isolates were obtained from the three conventional farms, and 79 E. coli and 80 Enterococcus spp isolates were obtained from the organic farm. All the E. coli isolates from both the conventional and organic pig farms were susceptible to ciprofloxacin, and all the Enterococcus spp isolates were susceptible to ampicillin, gentamicin and vancomycin. Isolates of E. coli from conventional pig farms were resistant to gentamicin (0.7%), neomycin (0.7%), ampicillin (2.7%), cotrimoxazole (11%), streptomycin (25%) and tetracycline (60%). Enterococcus spp isolates from the same farms were resistant to erythromycin (68%), tetracycline (66%), streptomycin (54%) and virginiamycin (49%). By contrast, for the organic pig farm 相似文献   

5.
Escherichia coli is commonly found in outbreaks of diarrhoea in mink during the production season although its role as a primary causal organism remains unclear. The present study was undertaken to determine the serogroups and antimicrobial susceptibility of E. coli isolates from healthy and diarrhoeic mink. Rectal swabs were taken from healthy and diseased animals, on six different farms, once at the onset of disease and again approximately 2 weeks later. The swabs were subjected to bacteriological investigation; a total of 210 E. coli were isolated, 98 from healthy animals and 112 from diseased. All isolates were serotyped and MICs were determined for nine antimicrobial compounds. Non-haemolytic isolates numbered 147, whereas 63 were haemolytic. Both haemolytic and non-haemolytic isolates were isolated from both healthy and diseased animals.A wide range of serogroups was detected, the most frequent being O2 (11.0%), O78 (11.0%), O153 (7.1%), O25 (5.7%), O6 (4.8%), and O15 (4.8%), but diarrhoea was not associated with specific serogroups. All isolates were sensitive to enrofloxacin, neomycin, gentamicin and colistin. In contrast, considerable variations in susceptibility were found among the six mink farms, for tetracycline (0-46.4%, average 21.9), ampicillin (2.9-50.0%, average 23.3), spectinomycin (8.0-35.7%, average 21.9), sulfamethoxazole (8.6-57.7%, average 30.0) and trimethoprim (0-35.7%, average 9.5). Resistance to tetracycline was statistically more prevalent among haemolytic than among non-haemolytic strains.In conclusion, serogrouping and haemolysin testing failed to identify any association with diarrhoeal disease and antimicrobial resistance was highly variable between different mink farms.  相似文献   

6.
旨在调查2019年湖南省部分地区不同来源的大肠杆菌对抗生素的耐药水平,为养殖合理用药提供参考。从4个市畜禽养殖场采集猪、鸡和鸭粪便285份,使用麦康凯琼脂培养基和伊红美蓝培养基对大肠杆菌筛选,利用基质辅助激光解析电离飞行时间质谱进行鉴定,采用微量肉汤稀释法检测16种抗生素对大肠杆菌的最小抑菌浓度(MIC)。共分离出203株大肠杆菌(鸡源146株、鸭源20株和猪源37株),对四环素和氨苄西林耐药率最高,分别达到89.2%和84.7%;对头孢他啶、奥格门丁、黏菌素耐药率较低,分别为2.5%、2.0%和0.5%;所有菌株均对美罗培南敏感。抗3种及以上抗生素的菌株数目占比为87.7%,而仅5.42%的菌株对所有检测的抗生素敏感。另外,来源于减抗示范养殖场的大肠杆菌对大部分抗生素的耐药率,与来源于非减抗养殖场大肠杆菌相比未见显著差异。上述结果表明,湖南省动物源大肠杆菌的耐药水平仍处在较高水平,重视兽药使用管理并持续开展对大肠杆菌的耐药性监测十分必要。  相似文献   

7.
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   

8.
为研究16S rRNA甲基化酶rmtB在猪肠道菌中的传播方式,用脉冲场凝胶电泳(PFGE)分别对来源于A、B猪场的48株rmtB阳性大肠埃希氏菌进行基因分型;用膜接合试验研究rmtB基因的水平传播方式;用微量稀释法对rmtB阳性菌及其接合子进行药敏试验。有45株rmtB阳性大肠埃希氏菌(45/48)能进行PFGE分型,可分为28种不同的PFGE基因型。其中来源于A猪场的20株菌可分为12种基因型,来源于B猪场的25株菌可分为16种基因型;46株rmtB阳性菌可以通过接合试验将rmtB基因及其介导的耐药性传递给受体菌E.coliC600和E.coli488 Rifr,接合频率从4.6×10-13~3.0×10-6不等,接合子对卡那霉素、阿米卡星、妥布霉素、西梭米星、萘替米星、庆大霉素6种二脱氧链霉胺类抗生素均高度耐药(MIC≥512μg/mL)。结果表明,rmtB基因位于接合性质粒上,该基因在两猪场的大肠埃希氏菌中既存在克隆传播,又存在水平传播,以水平传播为主。  相似文献   

9.
In order to understand the resistance of E.coli to clinical antimicrobial drugs from different farms in Kuitun area of Xinjiang,the bovine fecal samples were collected using the anal swab and E.coli was isolated from 123 (30),127 (30) and 128 (30) farms,respectively.The minimum inhibitory concentrations of E coli isolated from fecal samples to 10 antimicrobial drugs were determined by agar dilution method and the difference of resistance rate of E.coli from different farms was compared by chi square test.The results showed that the resistance rates of 128 farm to amoxicillin/clavulanic acid (33.3%) and apramycin (23.3%) were relatively high;The resistance rates of 127 farm to ampicillin (20.0%),amoxicillin/clavulanic acid (16.7%) and florfenicol (16.7%) were relatively high;The resistance rates of 123 farm to ampicillin (13.3%) and the apramycin (13.3%) were relatively high.The chi square test results showed that resistance rates of E.coli to florfenicol and enrofloxacin from 127 farm were significantly higher than that from 123 and 128 farms (P<0.05);The resistance rates of E.coli to amoxicillin/clavulanic acid and apramycin from 128 farm were significantly higher than that from 123 and 127 farms (P<0.05),respectively.The most of the antibiotics resistance pattern of E.coli from different farms was 1 to 2 resistant.The results showed that the drug resistance rates of bovine E.coli in Kuitun was not high,while the resistance rates to commonly used drugs such as amoxicillin/clavulanic acid and apramycin were high.It suggested that this kinds of antimicrobial drugs should be replaced or avoid using to treat bacterial diseases.In addition,the antimicrobial resistance between farms was different,indicating the farms medicine would impact the drug resistance in bacteria.  相似文献   

10.
To investigate the effects of rearing practices of commercial broiler chickens on the incidence of antimicrobial resistance in commensal Escherichia coli isolates, fecal E. coli isolates obtained in 4 farms were screened for anitimicrobial resistance. Ten E. coli isolates were recovered from each of the fecal samples collected from 10 birds in the farms at the ages of 2 days, 14-17 days, and 47-50 days. In 2 out of the 4 farms, no antimicrobials were used during the rearing period. In the other two farms, following collection of the fecal samples at 14 and 15 days of age, oxytetracycline (OTC), sulfadimethoxine (SDMX), and tylosin were given to birds on one farm and SDMX was used in the other. Isolates resistant to ampicillin and OTC that were obtained from an untreated flock at different sampling times were closely related to each other by pulsed-field gel electrophoresis patterns (PFGE) of XbaI-digested chromosomal DNA. PFGE analysis together with in vitro conjugation experiments suggested that diversity of resistance phenotypes within a clone may be resulted from the acquisition and loss of R-plasmids in an untreated and a treated flock. The numbers of resistance phenotypes observed among fecal isolates increased during the growth of the chickens in all the farms. The results in the present study suggest that persistence of commensal E. coli strains resistant to antimicrobials even in the absence of antimicrobial administration. It is also hypothesized that horizontal transmission of resistance determinants resulted in the emergence of different resistance phenotypes in those farms.  相似文献   

11.
新疆奎屯地区不同团场牛源大肠杆菌耐药情况比较   总被引：2，自引：0，他引：2  
为了解新疆奎屯地区不同团场牛源大肠杆菌对临床常用抗菌药物的耐药情况,比较不同养殖场之间牛源大肠杆菌的耐药差异,分别从新疆奎屯地区位于123团、127团和128团的牛场,用肛拭子在直肠采集粪样各30份,并分离大肠杆菌。采用微量肉汤稀释法,对分离出的大肠杆菌进行10种抗菌药物最小抑菌浓度的测定,通过卡方检验对不同养殖场牛源大肠杆菌耐药差异性进行比较分析。结果显示,128团对阿莫西林/克拉维酸（33.3%）和安普霉素（23.3%）耐药率相对较高;127团对氨苄西林（20.0%）、阿莫西林/克拉维酸（16.7%）和氟苯尼考（16.7%）耐药率相对较高;123团场对氨苄西林（13.3%）和安普霉素（13.3%）耐药率相对较高。卡方检验结果显示,127团对氟苯尼考和恩诺沙星的耐药率显著高于123团和128团（P<0.05）;128团对阿莫西林/克拉维酸和安普霉素的耐药率分别显著高于123团和127团（P<0.05）。不同团场多重耐药均以1～2耐为主。结果表明,新疆奎屯地区不同团场牛源大肠杆菌对多数被检药物的耐药率不高,仅对常用药物如阿莫西林/克拉维酸和安普霉素等具有较高耐药率,需在临床治疗细菌疾病时更换或避免使用此类抗菌药物。此外,各养殖场对被检抗菌药物的耐药情况不同,说明养殖场的用药极大程度影响细菌的耐药性。  相似文献   

12.
为了掌握河南省鸡源大肠杆菌的耐药性情况,从规模化鸡场抽取样品120批,通过细菌的分离、纯化,采用BD Phoenix^TM-100全自动微生物鉴定系统对分离的大肠杆菌进行鉴定,并通过微量肉汤稀释法对分离菌株进行药物敏感性分析。结果显示,共分离菌株100株,分离率为83.3%。分离菌株对四环素、氨苄西林、磺胺异噁唑、恩诺沙星、复方新诺明耐药严重,耐药率均在80%以上,表明河南省鸡源大肠杆菌耐药情况较为严重。  相似文献   

13.
OBJECTIVE: To describe antimicrobial susceptibility patterns in Campylobacter spp isolated from dairy cattle and farms managed organically and conventionally in the midwestern and northeastern United States. DESIGN: Longitudinal study. SAMPLE POPULATION: 128 farms. PROCEDURE: Samples and data were collected every 2 months from August 2000 to October 2001. Fecal samples were collected from calves and cows. Milk samples were obtained from the bulk tank and milk line filters. Environmental samples were obtained from a water source, feed bunks of lactating cows, and cattle housing areas. Campylobacter identification and antimicrobial susceptibility testing were performed at a central laboratory by use of microbroth dilution with 2 customized antimicrobial susceptibility panels. RESULTS: 460 and 1,570 Campylobacter isolates were obtained from organic and conventional dairy farms, respectively. Most isolates from both farm types were susceptible to most antimicrobial agents tested, and antimicrobial susceptibility of conventional dairy isolates was decreased, compared with organic dairy isolates. Low proportions of isolates resistant to ampicillin (< 10%) and moderate proportions resistant (30% to 60%) to kanamycin, sulfamethoxazole, and tetracycline were observed on both farm types. The proportion of isolates resistant to tetracycline was higher for conventional than organic farms. CONCLUSIONS AND CLINICAL RELEVANCE: Campylobacter isolates from dairy cattle and farms managed organically and conventionally had similar patterns of antimicrobial resistance; the proportion of resistant isolates was higher for conventional than organic farms.  相似文献   

14.
OBJECTIVE: To estimate the association between ceftiofur use and the isolation of Escherichia coli with reduced ceftriaxone susceptibility from fecal samples of dairy cow populations. ANIMALS: 1,266 dairy cows on 18 farms in Ohio. PROCEDURES: Individual fecal samples from all cows in the study herds were tested for Escherichia coli with reduced ceftriaxone susceptibility. Herd antimicrobial use policy and antimicrobial treatment records were also obtained. Plasmid DNA from these isolates was tested for the presence of the AmpC beta-lactamase gene (blaCMY-2). Minimum inhibitory concentrations to a standard panel of 16 antimicrobial drugs were determined by use of a broth microdilution system. RESULTS: Herds for which ceftiofur use was reported were more likely to have cows from which reduced susceptibility E coli was isolated than herds that did not report ceftiofur use (odds ratio, 25.0). However, at the individual cow level, no association was found between recent ceftiofur treatment and isolation of reduced-susceptibility E coli (adjusted odds ratio, 1.01). No observed linear relationship was found between the percentage of cows from which E coli with reduced ceftriaxone susceptibility was isolated and the percentage of cows in the herd recently treated with ceftiofur. CONCLUSIONS AND CLINICAL RELEVANCE: Our observation of a herd-level but not an individual cow-level association between ceftiofur use and isolation of E coli with reduced ceftriaxone susceptibility from fecal samples suggests that interventions to reduce the spread of antimicrobial resistance genes in agricultural animals will be most effective at the herd level.  相似文献   

15.
The epidemiology of subclinical salmonellosis in wild birds in a region of high Salmonella prevalence in pigs was studied. Three hundred and seventy‐nine faecal samples from 921 birds trapped in 31 locations nearby pig premises, and 431 samples from 581 birds of 10 natural settings far from pig farms were analysed for the presence of Salmonella spp. Positive samples were serotyped and analysed for antimicrobial resistance (AR). Phage typing and pulsed‐field gel electrophoresis (PFGE) on Salmonella Typhimurium isolates were also carried out. The overall proportion of Salmonella‐positive samples was 1.85% (95% CI = 0.93, 2.77). Salmonella isolation was positively associated with samples collected from birds in the proximity of a pig operation (OR = 16.5; 95% CI = 5.17, 52.65), and from non‐migratory (or short‐distance migration) birds (OR = 7.6; 95% CI = 1.20, 48.04) and negatively related to mostly granivorous birds (OR = 0.4; 95% CI = 0.15, 1.13). Salmonella Typhimurium was the most prevalent serotype and four different XbaI PFGE patterns were observed that matched the four phage types identified (U310, U311, DT164 and DT56). Only 20% of the strains showed multi‐AR. In three farms, a high degree of homogeneity among isolates from different birds was observed. These findings suggested that pig farms may act as amplifiers of this infection among wild birds, and the degree of bird density may have much to do on this transmission. Some of the Salmonella serotypes isolated from bird faeces were of potential zoonotic transmission and associated with AR. Monitoring salmonellosis in wild bird is advised.  相似文献   

16.
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   

17.
The main objectives of this study were to determine the prevalence and patterns of antimicrobial resistance in pigs on farms that medicated swine ration and those that did not. A total of 940 isolates of Escherichia coli from 188 pooled fecal samples obtained from weaner and finisher pigs on 47 farrow-to-finish swine farms (34 farms used in-feed medication and 13 did not) were tested for susceptibility to 21 antimicrobials using a breakpoint concentration method. The prevalence of resistance varied widely (0.0% to 81.3%) among the antimicrobials tested. Ninety percent of all the isolates tested were resistant to one or more antimicrobials. The most common multi-drug resistance patterns were to 2 to 6 antimicrobials. Resistance was significantly more frequent (P < 0.01) on farms that used in-feed medication compared to those that did not, and significantly more frequent (P < 0.01) in weaner pigs compared to finisher pigs. These findings indicate that resistance to a broad range of antimicrobials was prevalent among fecal E. coli isolates of pigs on study farms, and that this constitutes a potential reservoir for resistance genes that could spread to pathogens. The findings also provide further evidence that use of medication in swine rations provides selective pressure for antimicrobial resistance in E. coli in pigs.  相似文献   

18.
为调查山东省禽源致病性大肠杆菌流行的血清型及耐药性,从山东部分地区的45家养禽场分离到致病性大肠杆菌96株,应用微量平板凝集试验进行了血清型鉴定,共鉴定出18种血清型,其中优势血清型6种,分别为O78、O2、O15、O18、O143、O88,占定型致病性菌株的64％。抗菌药物敏感性试验发现,96株大肠杆菌对20种药物有不同程度的耐药性。75％以上的菌株对氨苄青霉素、阿莫西林、土霉素等5种抗菌药耐药,50％以上的菌株对卡那霉素、多西环素、环丙沙星等7种抗菌药表现为耐药;所有分离株存在多重耐药现象,75％的受检菌对9种或9种以上的被测药物耐药。结果表明,O78、O2、O15、O18、O143、O886种血清型是山东省部分地区近年来禽源致病性大肠杆菌的优势血清型,且禽源致病性大肠杆菌的耐药现象严重,有必要加强耐药性检测,以指导兽医临床合理使用抗菌药物。  相似文献   

19.
One hundred and thirteen finishing pig units and 74 sow units in Catalonia, Spain, were examined to determine the prevalence of salmonella infections and the factors that could be associated with them. Pooled faecal samples were taken from the finishing units, and samples of faeces were collected from individual sows. The Salmonella isolates were serotyped, phage typed and examined for their antimicrobial susceptibility to 18 common antimicrobial drugs. In addition, blood samples from pigs on 141 farms were analysed by ELISA. In both the bacteriological and serological surveys, a questionnaire with 84 questions was completed for each farm. Salmonella species were isolated from 20 per cent of the finishing units and 24 per cent of the sow units; 14 serotypes were detected in the finishing pigs and 11 in the sows. More than 30 per cent of the strains were resistant to tetracycline, sulphonamides, ampicillin or streptomycin, and 69 per cent of the strains were resistant to three or more agents up to 10 compounds. Seventy-seven per cent of the farms had at least one seropositive animal, and 26 per cent of these farms had an individual seroprevalence of 50 per cent or more. The factors associated (P<0.05) with the excretion of Salmonella species in the finishing units were the practice of raising livestock other than pigs (odds ratio [OR]=6.18), the herd size (OR=5.87), and a past history of clinical salmonellosis (OR=4.97). For the sows, the factors associated (P<0.05) with the excretion of Salmonella species were having open-flushed drainage of sewage (OR=34.48), a lack of rodent control measures (OR=0.05) and the number of sows in the unit (OR=9.26). Factors associated with seropositivity in the finishing units were a lack of bird-proof nets (OR=0.30) and the use of water from private wells (OR=3.64).  相似文献   

20.
Antimicrobial use is heavily restricted on organic farms; however, few studies have been conducted to investigate the impact this has on the epidemiology of resistance in pathogenic and commensal bacteria. We investigated the persistence of antimicrobial resistant Escherichia coli within an organic beef herd over a period of 28 months. Faecal samples collected monthly from three calf cohorts and annually from adult cattle and environmental samples, were screened for the presence of ampicillin, apramycin and nalidixic acid resistant E. coli. The prevalence of ampicillin resistance ranged from 27.3 to 40.7% in the annual herd and environmental samplings (n=22-55) and was greater in the calf cohorts, with a peak cohort prevalence of >47% in all 3 years (n=16-18). Apramycin and nalidixic acid resistant E. coli were rare. Pulsed-field gel electrophoresis (PFGE) identified 10 main genotype groups within the herd, with evidence of strain transmission between different livestock groups, animal species and years. Multiple resistance was found in >44% of isolates tested, with ampicillin, neomycin, sulphamethoxazole and tetracycline carriage the commonest phenotype identified. PCR detected the presence of class 1 integrons in <5% of resistant isolates, 6/7 of which were of cattle origin. These data demonstrate that ampicillin resistant E. coli was common on the farm despite restricted antimicrobial use, although strain diversity was low. Persistence of defined genotype groups was observed between years, together with the transmission of resistant strains between different animal species on the farm.  相似文献   

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