首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
The in vitro activities of 14 anti-microbial agents were determined against 92 strains of E. coli isolated from lambs (60 strains) and kids (32 strains) affected by neonatal diarrhoea. The overall percentage of resistant strains to streptomycin, sulphadimethoxine and tetracycline was very high (above 70%). A high level of resistance (from 30% to 50%) to ampicillin, kanamycin, neomycin and chloramphenicol was also detected. The E. coli strains were highly susceptible to cephalosporins, polymyxin and quinolones. Most of the strains showed multiresistance: 77.2% of isolates were resistant to at least two antibiotics, 55.4% were resistant to at least four antibiotics and 33.7% were resistant to at least six antibiotics. A total of 34 antibiotypes could be distinguished.  相似文献   

2.
In order to clarify the pathogenic characteristics and drug-resistant spectrum of a newborn piglet diarrhea outbroke recently in a large-scale pig farm of Henan province, the study was carried out by the isolation of intestinal pathogenic Escherichia coli and system identification. Escherichia coli strains were isolated from the faeces of diarrhea piglets. 13 virulent genes were tested by PCR. The antibiotic susceptibility of the strains was determined. The results showed that the positive rate came up with 34.8% for EAST1 gene. All of the strains were multiple-drug resistance and resistant to at least 5 types of antibiotics. 75.3% strains were resistant to more than 9 types of antibiotics. All of the strains were resistant to ampicillin, piperacillin, ciprofloxacin, levofloxacin and moxifloxacin. The result of the phylogenetic background showed that 21.7% E.coli isolates belonged to group B2 and D which were pathogenic. According to the synthesis analysis of virulence factors, resistance and phylogenetic background of the strains isolated from the diarrhea piglets, proper clinical treatment and prevention and control measure could be provided.  相似文献   

3.
为明确河南地区一规模化猪场暴发新生仔猪腹泻疫情的病原特性及其耐药谱,本研究对肠道致病大肠杆菌进行了分离鉴定。对腹泻仔猪粪便中分离的大肠杆菌进行13种毒力基因检测和21种抗生素的药敏试验。结果显示,34.8%分离株检出EAST1基因;所获分离株均为多重耐药菌株,且至少对5类抗生素耐药,耐9类以上抗生素的菌株达到75.3%,对氨苄西林、哌拉西林、环丙沙星、左氧氟沙星和莫西沙星耐药率达到100.0%。细菌种系进化分群结果显示,21.7%分离株属于有致病性的B2群和D群。本研究获得了腹泻仔猪大肠杆菌分离株的毒力基因、耐药谱的基本数据和种系进化分群的遗传背景,为制定有针对性的治疗和防控技术方案提供依据。  相似文献   

4.
Three-hundred faecal swabs were obtained from pigs with diarrhoea in farms located in different areas of the Ribeirao Preto region in the State of Sao Paulo. One-hundred Escherichia coli strains were isolated and tested for production of thermolabile (TL) and thermostable (STRa and STb) enterotoxins, and for the presence of colonization factors F4, F5 and F6. The strains were also tested for sensitivity to 14 antibiotics and chemotherapeutic agents. Twenty-four Escherichia coli strains produced enterotoxin STb, 5 produced LT and 3 produced STa. In the mannose-resistant haemagglutination reaction, one strain reacted positively with sheep, chicken, horse and human red blood cells and another reacted positively with guinea pig, sheep, chicken, horse and human red cells. However, both strains were negative for colonization factors F4, F5 and F6 when submitted to the slide agglutination test. All Escherichia coli strains were resistant to at least one antibiotic, the highest percentages being obtained for resistance to penicillin, tetracycline and cephalotin. In addition to the importance of the virulence factors normally encountered in enterotoxigenic Escherichia coli strains from pigs, the present results show the possible existence of new colonization factors other than F4, F5 and F6 participating in E. coli-induced pigs colibacillosis in the Ribeirao Preto region.  相似文献   

5.
Of 470 Gram-negative facultative anaerobes isolated from cases of bovine mastitis in England and Wales, 422 were identified as Escherichia coli. The characteristics of 237 of these were investigated. Guinea-pig red cell haemagglutinins were possessed by 86% of strains and 12% were resistant to D-mannose. None of the strains tested invaded Vero cells. Haemolysin, Vero toxin and enterotoxin were produced by 5, 0.5 and 1% of strains, respectively. Twenty-two percent were resistant to one or more antibiotics and 4% to sodium arsenate. Transfer ability was possessed by 41% and lysogenic phage by 27% of strains; 62% possessed either one or the other and 12% possessed both. Colicin production was detected in 18% of strains; 5% produced Colicin V. Ninety-nine percent of strains were serum-resistant, while only 6% were able to grow well in bovine serum. A microscopically visible capsule was seen in 75% of strains. All strains possessed at least one of the potential virulence factors or markers studied. Several strains which possessed one characteristic only (mannose-sensitive haemagglutination or serum resistance), possessed one or more large molecular weight plasmids. None of the strains was particularly virulent for chickens following intramuscular inoculation. Of the strains which possessed one virulence characteristic, only those which were serum-resistant were re-isolated from expressed milk following intramammary inoculation of lactating cows.  相似文献   

6.
The ability of bacteria to survive in serum is considered a likely virulence determinant in diseases where the infective bacteria become septicaemic. Optimal conditions were established to test the survival of Pasteurella multocida in chicken serum. Serum was used at 90%, the inoculum was 10(3)-10(4)cfu in phosphate buffered saline pH 7.4. Survival was measured after incubation for 2-4 h; if survival was <50% the strain was considered serum susceptible. Susceptible strains were either killed or their growth was inhibited. Some resistant strains not only survived but grew rapidly in unheated serum. Thirty-five strains, all originally isolated from clinical fowl cholera, were tested; eight were susceptible, of which three were killed and five inhibited, and the remainder (27) were resistant. Ten serum-resistant P. multocida serogroup A strains were grown in hyaluronidase to remove the capsule and survival in chicken serum was re-tested. Three strains became susceptible, while seven strains remained resistant. Three serum susceptible strains were then tested in the presence of cytidine monophosphate-N-acetylneuraminic acid (CMP-NANA). This substance is present in the human serum, and is known to mask the effect of complement on Neisseria gonorrhoeae rendering susceptible strains resistant. Two of the three serum susceptible strains became resistant in the presence of CMP-NANA. Serum susceptibility/resistance was more complex than that of Escherichia coli, and the role of resistance to avian complement in the pathogenesis of fowl cholera remains to be determined.  相似文献   

7.
The sensitivity of strains of Escherichia coli isolated from calves, piglets, lambs and kids in Trinidad to seven antibiotics was determined. Two hundred and sixty-four (91.3%) of 289 strains isolated from diarrhoeic animals and 173 (87.4%) of 198 strains from non-diarrhoeic animals exhibited resistance to one or more antibiotics. The difference was not statistically significant (P > or = 0.05; X2). Regardless of health status, isolates from lambs were least resistant (75.0%) and those from piglets most resistant (96.7%) and the difference was significant (P < or = 0.001; X2). Strains of E. coli were most resistant to streptomycin (81.3%) and tetracycline (78.9%) and least resistant to chloramphenicol (4.3%) and gentamycin (4.7%). The predominant antibiotic resistance pattern for isolates from all sources was streptomycin-tetracycline (27.9%). It was concluded that the widespread prevalence of resistance to antibiotics reflects their misuse in the local environment.  相似文献   

8.
In order to characterize potential pathogenic Escherichia coli strains isolated from diarrheic hens and chickens originating from intensive battery rearing in North Algeria, the presence of a large range of virulence factors and markers was studied in 50 strains by DNA-DNA hybridization on colonies and phenotypic tests. The sequences we focused on were those coding for adhesins F5, F41, F17, Pap, Afa, and Sfa; intimin Eae; and toxins STa, STb, LT1, Stx1, Stx2, CNF1, and CNF2. The phenotypes explored were the colicins, aerobactin, hemolysins, and hemagglutinin production and serum resistance. The genotypic and phenotypic tests enabled us to categorize the isolates into two distinct groups: those with a potential to invade the host (27 strains were serum resistant and/or produced aerobactin), among which three strains were also potentially diarrheagenic, one strain was LT1 + F17+ Afa+ Pap+ (enterotoxigenic E. coli) and the two others were Stx1 (verotoxigenic E. coli). Twenty-three strains were colicinogenic, including 19 strains producing colicin V. This latter factor was also detected in isolates negative for the other virulence factors. On the basis of the type of erythrocytes agglutinated, we established 14 mannose-resistant hemagglutination patterns among the 37 strains tested, including 22 serum-resistant and/or aerobactin producing strains and 15 strains negative for these two characters. None of the strains produced alpha hemolysin, whereas two strains produced beta hemolysin and enterohemolysin, respectively. Congo red fixation was observed in 25 strains. No relationship could be detected between Congo red fixation and the presence of other virulence markers, such as serum resistance and aerobactin production. This study shows that among isolates originating from the feces of diarrheic chickens, the proportion of potentially diarrheagenic E. coli strains is low.  相似文献   

9.
河北省犊牛腹泻大肠杆菌致病性及耐药性分析   总被引：1，自引：0，他引：1  
为确定河北省犊牛腹泻大肠杆菌的致病性与耐药性,本研究对2018年1月至2019年6月期间从河北省石家庄、保定、承德、唐山、廊坊的部分肉牛场腹泻犊牛样品中分离到的50株大肠杆菌进行了致病性试验、药物敏感性试验、毒力基因和耐药基因检测。结果显示:50株分离菌均对小鼠具有致病性,致病菌占比100%(50/50)。毒力基因fyuA、irp2、eaeA、ler检出率分别为68.0%、66.0%、34.0%、34.0%。50株分离菌均对15种抗生素中的2种及以上表现为耐药,对10种及以上抗生素耐药的菌株占比达34%(17/50);分离菌对土霉素、磺胺对甲氧嘧啶、磺胺间甲氧嘧啶、替米考星4种药物表现为高度耐药,耐药率分别为90%、90%、94%、100%。除四环素类tetD基因检出率为0外,其它耐药基因均有检出,其中四环素类tetC、氨基糖苷类aadA1、喹诺酮类gyrA、gyrB基因检测率高达100%。试验的50株大肠杆菌均具有较强的毒力和多重耐药性。本研究为河北省大肠杆菌所致犊牛腹泻病的防治提供了实验依据。  相似文献   

10.
Lee JH 《Veterinary microbiology》2009,135(3-4):401-405
The present study was to investigate antimicrobial resistance profiles of Escherichia coli O26 and O111 from cattle and to characterize the virulence genes of the resistant isolates. This paper reports the high prevalence of antimicrobial resistant E. coli O26 and O111 from cattle. Among 37 E. coli O26 and 25 E. coli O111 isolates from the fecal specimens obtained from cattle, 26 (70%) and 15 (60%) were resistant to at least one antibiotic, respectively. Forty (98%) of the 41 resistant isolates were resistant to two or more antibiotics. Among the 22 antibiotics tested in this study, ampicillin was the most common antibiotic that the isolates were resistant to, followed by tetracycline and streptomycin. None of the isolates were resistant to fluoroquinolones, such as ciprofloxacin, ofloxacin and norfloxacin, and to ceftriaxone, amikacin and imipenem. Eighteen different resistant types among the 41 isolates were observed by the cluster analysis. The most frequent antibiotic-resistance type was ampicillin-tetracycline-streptomycin-cephalothin-sulfisoxazole-ticarcillin-kanamycin-minocycline-piperacillin-chloramphenicol, which accounted for 9 (22%) of the resistant isolates. The observation of frequent and multiple resistances to antibiotics highlights the need for their careful use if their benefits are to be preserved. PCR analysis of the EHEC virulence markers showed that 25 of the resistant E. coli O26 and O111 isolates tested positive for stx2 or both stx1 and stx2. This suggests that the majority of these isolates can cause serious diseases in humans and may complicate the future therapeutic options under development.  相似文献   

11.
[目的]为了分析河西走廊地区犊牛腹泻致病性大肠杆菌携带毒力基因和耐药性情况,[方法]2020—2021年在河西走廊地区采集患腹泻病犊牛的粪便、肛拭子及肝脏等病料组织279份,采用人工感染试验动物、PCR方法和K-B药敏纸片法分别检测犊牛腹泻性大肠杆菌致病性、毒力因子和耐药性。[结果]结果表明,分离得到了126株大肠杆菌,其中79株犊牛腹泻性大肠杆菌能引起小鼠死亡;分离的79株致病性大肠杆菌的毒力基因crl、irp2、fimH、papC、K88、K99、stx1、stx2检测率在40.5%～100%之间,其他毒力基因检测率在15.2%～34.2%之间;分离的79株致病性大肠杆菌对氨苄西林、阿莫西林、新霉素等8种药物的耐药率在49.4%～96.2%之间,对其他药物的耐药率在5.1%～32.9%之间。[结论]从河西走廊地区患腹泻病犊牛病料组织中分离得到79株致病性大肠杆菌,这些菌株携带多种毒力基因,对临床中常用的抗菌药物产生了耐药性。  相似文献   

12.
The study was carried out to investigate the incidence of Escherichia coli O157 in raw materials, foodstuffs and the agricultural environment. Of a total of 987 samples examined, 22 strains (2.2%) were identified as E. coli O157 and 10 of them as E. coli O157:H7. Cefixime-Tellurite MacConkey sorbitol agar (CT-SMAC) agar and Biosynth culture medium (BCM) E. coli O157:7 medium were used for the isolation. The virulence factors (stx1, stx2, eae, and ehxA genes) were identified by polymerase chain reaction (PCR). Most strains were isolated from the mechanically deboned poultry meat (nine), minced meat (six) and raw milk (four). One strain was isolated from beef carcass and two strains from waste water. No strains were were found in mass for sausages, refreshment salads, swabs of pork and poultry carcasses and faeces of cattle and pigs. Ten strains from the 22 identified proved to be positive for all factors of virulence. They were isolated from minced meat (four), raw milk (four), waste water (one) and swab from beef carcass (one). Sensitivity to the antimicrobial drugs ampicillin (AMS), ampicillin-sublactam (SAM), tetracycline (TET), ofloxacine (OFL), cefuroxime (CRX), chloramphenicol (CPM), gentamicine (GEN), colistin (COL), cephalozine (CLZ), cefoxitin (CXT), aztreonam (AZT), and sulphamethoxazole + trimethoprim (COT) was tested using the standard dilution technique and disc diffusion test. Minimum inhibitory concentrations (MIC) characteristics (MIC(50), MIC(90), MIC range) and inhibitory zone diameter were determined for each strain. As determined by MICs, the resistance to tested antibiotics in E. coli O157 isolates was found to AMS (90.9%), CLZ (81.8%), CRX (63.6%), CXT (72.7%), CPM (72.7%), TET (81.8%), SAM (59.1%), COT (9.1%), COL (63.61%), AZT (9%) and GEN (4.5%). The similar results were obtained using the disc diffusion method. The differences were found relating to SAM, CXT, CMO and TET. Resistance against one or more antibiotics was found in 95.4% of E. coli O157. Only one strain was susceptible to all tested antibiotics. Most of the strains were resistant to ampicillin and cephalozine. Eight different resistance phenotypes were demonstrated in E. coli O157.  相似文献   

13.
The prevalence of antibiotic resistant Escherichia coli in the rectal flora of 168 healthy dogs and 93 cats in the Brisbane area was investigated. Rectal swabs were plated on MacConkey agar with and without antibiotics, and 690 isolates confirmed as faecal E. coli were tested for resistance to tetracycline, streptomycin, chloramphenicol, ampicillin, neomycin, furazolidone and sulphanilamide. Resistant isolates were obtained from 101 (60%) of the dogs and 24 (26%) of the cats sampled. A high percentage of the isolates was resistant to tetracycline, streptomycin, ampicillin and sulphanilamide. Multiple resistance to 3 or more of the drugs was exhibited by the majority of isolates and a total of 31 different multiple resistance patterns was demonstrated. Of the 50 strains tested for transfer of resistance, 30 (60%) transferred some or all of their resistance determinants to an E. coli K12F - recipient.  相似文献   

14.
Antimicrobial resistance is an emerging concern to public health, and food-producing animals are known to be a potential source for transmission of resistant bacteria to humans. As legislation of the European Union requires to ban conventional cages for the housing of laying hens on the one hand, and a high food safety standard for eggs on the other hand, further investigations about the occurrence of antimicrobial resistance in alternative housing types are required. In this study, we determined antimicrobial resistance in indicator bacteria from 396 cloacal swabs from 99 Swiss laying hen farms among four alternative housing types during a cross-sectional study. On each farm, four hens were sampled and exposure to potential risk factors was identified with a questionnaire. The minimal inhibitory concentration was determined using broth microdilution in Escherichia coli (n=371) for 18 antimicrobials and in Enterococcus faecalis (n=138) and Enterococcus faecium (n=153) for 16 antimicrobials. All antimicrobial classes recommended by the European Food Safety Authority for E. coli and enterococci were included in the resistance profile. Sixty per cent of the E. coli isolates were susceptible to all of the considered antimicrobials and 30% were resistant to at least two antimicrobials. In E. faecalis, 33% of the strains were susceptible to all tested antimicrobials and 40% were resistant to two or more antimicrobials, whereas in E. faecium these figures were 14% and 39% respectively. Risk factor analyses were carried out for bacteria species and antimicrobials with a prevalence of resistance between 15% and 85%. In these analyses, none of the considered housing and management factors showed a consistent association with the prevalence of resistance for more than two combinations of bacteria and antimicrobial. Therefore we conclude that the impact of the considered housing and management practices on the egg producing farms on resistance in laying hens is low.  相似文献   

15.
Two hundred and twenty-six strains of E. coli were isolated from faeces of 107 pigs at different ages and without clinical signs of infectious diseases. The resistance of the strains to sulphonamide, tetracycline, streptomycin, chloramphenicol, ampicillin, and nalidixic acid was determined. In 74 % of the animals the predominant E. coli flora was found to be resistant to one or more of the drugs mentioned. Fifty-three % of the strains were resistant. Multiple resistance was predominant among resistant strains (67 %). R factors transmissible to a sensitive strain of E. coli K12 W3132 were demonstrated in 28 %. The proportion of resistant strains was largest in young animals (0–14 weeks) accounting for 65 % of the strains isolated, as compared to 43 % of strains from pigs and sows (6 months or more). The incidence of resistance to sulphonamide, tetracycline, and streptomycin was high, whereas most of the strains were sensitive to ampicillin and chloramphenicol. All strains were sensitive to nalidixic acid.The incidence of resistance to antibiotics in a population of pigs to whom these drugs are not fed but applied as therapeutic agents solely seems rather high. When based on clinical findings only, the value is therefore questionable of sulphonamide, tetracycline and streptomycin treatment of infectious diseases caused by E. coli.  相似文献   

16.
This study was designed to explore the effect of nitrogen and phosphorous on the resistance of E.coli from environment and the mechanism.Microcosms were established to study the effect of nitrogen and phosphorous on the resistant phenotype of E.coli to chloramphenicol (CHL).cat gene of isolated drug-resistant strains and susceptible strains were detected.The results showed that,different concentration of nitrogen and phosphorous could induce the formation of antibiotics resistance of E.coli to CHL.The rate of cat gene of 46 strains of chloramphenicol resistant E.coli was 89.13%,which was 0 in the 16 strains of chloramphenicol sensitive E.coli.The results indicated that,nitrogen and phosphorous in the microcosms could induce the formation and maintenance of resistance to chloramphenicol in E.coli,which had correlation with cat gene.  相似文献   

17.
Antibiotic susceptibility of bacteria isolated from nasal swabs and lungs of pigs, to 16 commonly used antibiotics, was determined by disc diffusion test. beta-lactams showed the best activity against Streptococcus suis (S. suis) (> 99% of susceptible strains). The lowest sensitivity of S. suis was evidenced to: tylosin, tetracycline and neomycin (50%, 40% and 25%, respectively). Isolates of Escherichia coli (E. coli) demonstrated the highest susceptibility to cephalosporin (85% strains), gentamicin and norfloxacin (over 74%). The lowest susceptibility of E. coli was demonstrated to tiamulin and penicillin (11.3% and 1.9%, respectively). Over 80% of Actinobacillus pleuropneumoniae (App) strains were susceptible to all antibiotics tested. The highest resistance of App, but demonstrated by below 20% of tested isolates only, was evidenced to neomycin and LxS. Isolates of Pasteurella multocida (Pm), Haemophilus parasuis (Hps) and Arcanobacterium pyogenes (A. pyogenes) were highly susceptible to the most antibiotics included in the analysis. The comparison of the in vitro susceptibility of pathogens to the chemotherapeutics used on Polish farms for the therapy of bacterial infection of pigs within the last five years and the last 10 years, showed an increasing percent of E. coli and S. suis strains resistant to commonly used antibiotics. It is also shown that Pm, Hps, App and A. pyogenes isolates were continuously susceptible to the most chemotherapeutics applied.  相似文献   

18.
The prevalence, virulence potential, and antibiotic resistance of ophthalmic Staphylococcus pseudintermedius (SP) isolated from dogs were examined. Sixty-seven Staphylococcus species were isolated from ophthalmic samples and surveyed for species-specific sequences in the Staphylococcus intermedius group (SIG) nuclease gene (SInuc), exfoliative toxin gene for SIG (siet), and antibiotic resistance genes (blaZ and mecA). PCR-restriction fragment length polymorphism analysis of the pta gene was also performed. Fifty isolates were identified as SIG strains, all of which were found to be SP. The blaZ gene was detected in 42 of the 50 SP strains and mecA gene was observed in 18 of the 50 SP strains. The 50 SP strains were most susceptible to amoxicillin/clavulanic acid (94%) and chlorampenicol (70%), and highly resistant to tetracycline (94%) and penicillin (92%). It was also found that 16 (88.9%) mecA-positive SP strains were resistant to oxacillin, tetracycline and penicillin. All mecA-positive SP were resistant to more than four of the eight tested antibiotics and therefore considered SP with multi-drug resistance (MDR). Our results indicate a high prevalence of antibiotic resistance genes in ophthalmic SP along with a close relationship between MDR SP strains and the mecA gene. Based on our findings, judicious administration of antibiotics to companion dogs is necessary.  相似文献   

19.
为探讨氮磷营养盐对环境大肠杆菌(E.coli)耐药性的影响及其机制,本试验通过建立模型生态系统研究氮磷营养盐引发大肠杆菌对氯霉素(CHL)产生耐药表型的影响,并对分离到的耐药菌株和敏感菌株进行cat基因检测.结果显示,添加不同剂量氮磷营养盐可引发大肠杆菌对氯霉素产生耐药性,46株耐氯霉素大肠杆菌cat基因的阳性率为89.13%;16株对氯霉素敏感的大肠杆菌未检出cat基因.结果表明,模拟生态系统中加入氮磷营养盐可引发大肠杆菌对氯霉素产生耐药;氮磷营养盐引发大肠杆菌对氯霉素耐药与cat基因有关.  相似文献   

20.
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   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号