【作者】 陈一兵；

【导师】 高崧； 彭大新； 田龙；

【作者基本信息】 扬州大学 ， 兽医， 2006， 硕士

【摘要】 肠产毒素性大肠杆菌(ETEC)是引起仔猪黄白痢的重要病原，仔猪黄痢发病率和死亡率均较高；仔猪白痢发病率较高，但死亡率较低，主要影响仔猪生长发育和降低饲料报酬而造成较大经济损失。近年来有关仔猪黄白痢的流行病学的报道较少，本文从华东地区分离鉴定出508株大肠杆菌，应用玻板凝集试验对其O血清型进行鉴定，508株分离株中，除145株未能定型、22株自凝外，341株分离株覆盖了71个血清型，以O101，O9，O20，O149，O107和O91等6个血清型为主，占定型菌株的50.4％，是这次致仔猪黄白痢大肠杆菌调查的主要流行血清型。从1995年至2006年保存的菌株中选取173株致病性大肠杆菌，进行14种抗菌药物的药敏试验，试验表明敏感率最高的是菌必治，敏感菌株达到161株；其次为多粘菌素B、丁胺卡那霉素敏感菌株分别达到142株和126株；而庆大霉素、环丙沙星、氟哌酸和氯霉素敏感菌株较少；强力霉素、氨苄青、链霉素、四环素、磺胺甲基异噁唑等常用药物均表现强烈的耐药性。受检菌株中只有1998年的一株无耐药性，其余均表现出不同程度的耐药性，且大部分集中于10重-12重耐药。结果显示，随着时间的推延，细菌对大部分抗生素的耐药性会越来越强。为了探讨大肠杆菌氨基糖苷乙酰转移酶(AAC)基因的分布规律及与氨基糖苷类抗生素耐药的相关性，对90株耐庆大霉素的猪大肠杆菌菌株检测，结果显示aac(3)-Ⅱ为主要钝化酶，检出率占71.1％；aac(6′)-Ⅰb其次，检出率占16.7％。这说明对猪源大肠杆菌aac(3)-Ⅱ是氨基糖苷类药物耐药的主要钝化酶之一，是引起相应耐药性的重要因素。更多还原

【Abstract】 Enterotoxigenic Escherichia coli (ETEC) is main pathogen of the piglet diarrhea, which can cause economic loss due to higher morbidity and mortality in yellow scour of newborn piglets, higher morbidity and lower mortality in while scour of piglets, poor growth rates, and decrease feed efficiency. The first purposes of this study was to determine the present distribution of O-serogroups among pathogenic Escherichia coli isolates collected from piglets with yellow and white diarrhea in partial regions of eastern China. Among 508 E.coli isolates, serogroups of 341 strains were determined while 145 were unable to be classified as certain groups, and 22 were self-agglutinated. These isolates distributed in 71 serogroups and main of which belonging to 6 O-serogroups : O101, 09, 020, O149, O107 and O91.In order to guide the clinical medication, antibiotic susceptibility of E. coil isolates was determined with t4 kinds of antibiotics. Among 173 E.eoli isolates, which were collected form 1995 to 2006 and stored in the laboratory, 161 strains were sensitive to Ceftriaxone, and 142 and 126 strains were sensitive to Polymyxin B and Kanamycin, respectively. These isolates show little sensitivity to Gentamicin, Ciprofloxacin, Norfloxacin, and Chloramphenicol, whereas resistant to Doxycycline, Ampicillin, Streptomycin, Tetracycline, and Sulfamethoxazole . A novel strain isolated in 1998 shows no drug resistance, meanwhile the others show drug resistance to almost 10～12 antibiotics. These data suggested that there is close correlation between the antibiotic resistance and the frequence of agents prescribed in clinic.To investigate the relationship between the presence of N-acetyltransferases (AAC) genes and the resistance of aminoglycoside of E.coli isolates, two pairs of primers of AAC genes were designed and PCR was performed. Among ninety strains of E.coli isolates which resistant to Gentamicin, 71.1% of isolates were aac(3)-Ⅱpositive, while 16.7% of isolates were aac(6’)-Ⅰb positive. The results suggested that aae(3)-Ⅱmaybe the main modifying enzyme of aminoglycoside in E.coli.更多还原