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浙江大学学报（农业与生命科学版）
浙江大学学报(农业与生命科学版)  2013, Vol. 39 Issue (1): 98-    DOI: 10.3785/j.issn.1008-9209.2012.03.191
动物科学     
腹泻仔猪病原性大肠埃希菌毒力因子分布与耐药性分析
张静， 姜中其*， 虞惠贞， 吴永福， 蒋明君
（浙江大学 动物科学学院，杭州 310058）
 
Distribution of virulence factors in pathogenic Escherichia coli isolates from diarrheal piglets and their antibacterial resistance
ZHANG Jing, JIANG Zhongqi*, YU Huizhen, WU Yongfu, JIANG Mingjun
(College of Animal Science, Zhejiang University, Hangzhou 310058, China
)
 全文: PDF(1717 KB)   HTML ( ) 
摘要： 为了探索仔猪大肠埃希菌性腹泻的发病机制、大肠埃希菌毒力因子变迁以及与耐药性可能存在的关系，在直肠棉拭采集浙江省规模猪场腹泻仔猪病料，经细菌分离纯化、形态学结合PCR鉴定以及小鼠致病性试验得到124株病原性大肠埃希菌基础上，应用PCR分析其毒力因子，采用K-B法及耐药性专用软件Whonet测定并分析其对抗菌药物的耐药性，最后，通过Logistic分析分离株毒力因子与耐药性的相关性。结果表明：菌毛阳性分离株（F4+和F41+）占总菌株数的7.26%（9/124），首次检测到毒力因子EAST1、PAA和AIDA-I，其中EAST1检出率高达19.68%（24/124），而PAA和AIDAI阳性率较低，分别为4.84%（6/124）和2.42%（3/124）；分离株对苯唑西林（100%）、复方新诺明（97.6%）、利福平（97.6%）、多西环素（96%）、羧苄西林（93.5%）、氨苄西林（93.5%）、阿莫西林（93.5%）耐药严重；链霉素与氨苄西林（75.45%）、恩诺沙星（65.45%）、复方新诺明（78.18%）、庆大霉素（63.64%）、多西环素（96%）、氟苯尼考（50.91%）间交叉耐药明显。分离菌株100%呈多重耐药，其中以14～16耐药最多（43.31%）；阿莫西林/克拉维酸（P=0.046）和多西环素的耐药性（P=0.020）与大肠埃希菌黏附与脱落病变eae(E．coli attaching and effacing) 基因显著相关, 多黏菌素B（P=0.004）和氯霉素的耐药性（P=0.013）与EAST1显著相关。结合以往资料，我们认为大肠埃希菌毒力因子已发生明显改变，耐药性更趋严重，且二者之间存在相关性，需深入研究以更好制订大肠埃希菌病有效防控措施。
Abstract: Diarrhea in preweaning and postweaning piglets is still a frequently occurring disease on
 scaled farms, and result in great economic losses. Enterotoxigenic Escherichia coli (ETEC) is a major cause, and
 the virulence factors are the key to its pathogenicity. The traditional and commonly detected pili of ETEC are F4（K88），F5（K99），F6（987P），F18 and F41, and the enterotoxins  include heatstable STa and STb，heatlabile enterotoxin LT and Stx2e. However, new reports
 have shown that ETEC strains lacking of recognized fimbriae are becoming increasingly common, which may be linked to the use of vaccines incorporating fimbriated strains, providing selection pressure for the acquisition and carriage of novel, unrecognized virulence genes. Recently, EAST1 (enteroaggregative Escherichia coli heatstable enterotoxin 1）， PAA (porcine attaching and effacingassociated factor),  AIDAI (adhesin involved in diffuse adherence）and intimin encoded by eae （Escherichia coli attaching and effacing） have been reported. Nevertheless, few related data have been available in China; furthermore, the prevention strategies have been devised largely based  on the virulence factors. In order to gain more insight into the pathogenesis of colibacillosis in piglets and control the disease, it is of significant importance to track the changes of E. coli virulence factors and antimicrobial resistance, and elucidate the possible relationship between them.
Samples were collected by rectum swabs from diarrheal piglets on intensive pig farms of Zhejiang Province. A total of 124 pathogenic isolates were obtained after bacteria isolation, purification, and identification based on the combination of morphology and PCR techniques. The virulence factors were verified by PCR with specific primer pairs. Susceptibility testing was carried out by KB method, and analyzed by Whonet software. The correction between antibacterial resistance and virulence factors was evaluated by Logistic regression analysis. The PCR results showed  that fimbriae positive (F4+ and F41+) amounted to 7.26% (9/124). EAST1, PAA and AIDAI were detected for the first time in the region. EAST1 turned out to be as high as 19.68% (24/124) of the isolates, whereas only 4.84% (6/124) and 2.42% (3/124) of the isolates harbored PAA and AIDAI, respectively. Isolates were highly resistant to oxacillin (100%), cotrimoxazole (97.6%), rifampicin (97.6%), doxycycline (96%), carbenicillin (93.5%), ampicillin (93.5%) and amoxicillin (93.5%). In addition, streptomycin showed serious crossresistance with ampicillin (75.45%), enrofloxacin (65.45%), gentamicin (78.18%), doxycycline (96%) and florfenicol (50.91%). Besides, all isolates were multidrug resistant among them, the majority
were resistant to 1416 antibacterial agents (43.31%).Moreover, virulence
 factor eae was found to be corrected with amoxicillin/clavulanic acid (P=0.046) and doxycycline (P=0.020) resistance, respectively. Similarly, there was a significant correction between EAST1 and polymyxin B (P=0.004), EAST1 and chloramphenicol (P=0.013), respectively. This investigation demonstrated  that prevalent virulence factors had  largely changed compared with previous studies, and resistance
was  still on the increase, furthermore, there existed  a correlation between them. Further research is required to better understand the complicated virulence factors, bacterial resistance and its subtle correction.  
出版日期: 2013-01-20
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张静
姜中其*
虞惠贞
吴永福
蒋明君

引用本文:

张静， 姜中其*， 虞惠贞， 吴永福， 蒋明君. 腹泻仔猪病原性大肠埃希菌毒力因子分布与耐药性分析[J]. 浙江大学学报(农业与生命科学版), 2013, 39(1): 98-.

ZHANG Jing, JIANG Zhongqi*, YU Huizhen, WU Yongfu, JIANG Mingjun. Distribution of virulence factors in pathogenic Escherichia coli isolates from diarrheal piglets and their antibacterial resistance. Journal of Zhejiang University (Agriculture and Life Sciences), 2013, 39(1): 98-.

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http://www.zjujournals.com/agr/CN/10.3785/j.issn.1008-9209.2012.03.191    或    http://www.zjujournals.com/agr/CN/Y2013/V39/I1/98

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