陕西某猪场仔猪腹泻病原菌的分离鉴定

发布时间：2018-12-07 09:33

【摘要】：引起仔猪腹泻的原因很多,包括病原微生物(病毒、细菌等)、饲料卫生、环境温度突然降低等,其中细菌性腹泻是影响仔猪健康生长、甚至导致仔猪死亡的重要原因之一。本研究的目的是对陕西某规模化猪场腹泻仔猪进行病原菌的分离鉴定,然后进行药敏试验,为猪场仔猪细菌性腹泻的有效防治提供参考。(1)2014年10月至2015年4月,在陕西某规模化猪场采集30日龄内腹泻仔猪的肛门拭子43份,经细菌分离培养、染色镜检和生化试验,结果表明,从这43个腹泻病料中都分离出了细菌,其中在每份病料中都分离出了大肠埃希菌,分离率为100%(43/43),其他细菌的分离率从高到低依次为变形杆菌18.60%(8/43),粪链球菌16.28%(7/43),芽胞杆菌13.95%(6/43),葡萄球菌9.3%(4/43),酵母菌9.30%(4/43),沙门菌2.33%(1/43)。(2)根据临床表现和分离鉴定结果,从初步诊断为大肠埃希菌所致疾病的病料中随机挑选三株分离到的大肠埃希菌进行小鼠致病性试验,在接种后18h左右3只小鼠全部死亡的有两株,说明分离菌株的致病性很强;对这三株大肠埃希菌进行血清型鉴定,血清型分别为O141(2株,致病)和O20(1株,不致病)。接种沙门菌的小鼠在接种后13h左右3只小鼠全部死亡,说明分离菌株的致病性很强;对疑似沙门菌进行血清型鉴定,确定为B群的鼠伤寒沙门菌(S.Typhimurium),血清型为O4。接种O21和变形杆菌的小鼠精神状况和饮食欲一直没有明显变化,也没有出现死亡,说明分离菌株致病力很弱或无致病性。对疑似沙门菌及变形杆菌进行了基因组序列测定,经NCBI Blast基因比对,所比对序列与目标序列的同源性都为99%,确定为沙门菌和变形杆菌。(3)药敏试验结果表明,大肠埃希菌对庆大霉素、环丙沙星、新霉素、卡那霉素、链霉素和恩诺沙星敏感,部分对四环素、氨苄西林钠耐药;沙门菌对头孢曲松钠敏感,对庆大霉素、四环素、氨苄西林钠、新霉素、卡那霉素、链霉素和恩诺沙星耐药;变形杆菌对庆大霉素、环丙沙星、卡那霉素、链霉素、恩诺沙星敏感,对头孢曲松钠、四环素、氨苄西林钠耐药。综上所述,可选用庆大霉素、卡那霉素、新霉素等对大肠埃希菌引起的仔猪腹泻进行药物治疗,对沙门氏菌引起的仔猪腹泻可以选用头孢曲松钠进行治疗。在引起仔猪腹泻的病原菌中,大肠埃希菌最为重要的病原菌;沙门菌的分离率虽然低,但分离菌株为鼠伤寒沙门菌,且分离菌株对大多数抗生素有耐药性。
[Abstract]:There are many causes of piglet diarrhea, including pathogenic microorganism (virus, bacteria), feed hygiene, environmental temperature suddenly reduced, among which bacterial diarrhea is one of the important factors that affect the healthy growth of piglets and even lead to the death of piglets. The purpose of this study was to isolate and identify pathogenic bacteria from piglets with diarrhea in a large scale pig farm in Shaanxi province, and then to carry out drug sensitivity tests to provide a reference for the effective prevention and treatment of bacterial diarrhea in piglets. (1) from October 2014 to April 2015, 43 anal swabs of diarrhea piglets within 30 days of age were collected from a large-scale pig farm in Shaanxi Province. The bacteria were isolated from 43 samples of diarrhea diseases by bacteria isolation, staining, microscopic examination and biochemical tests. Among them, Escherichia coli was isolated from each sample, the isolation rate was 100% (43 / 43), the isolation rate of other bacteria was 18.60% (8 / 43) of Proteus and 16.28% (7 / 43) of Streptococcus faecalis. Bacillus 13.95% (6 / 43), Staphylococcus 9.3% (4 / 43), yeast 9.30% (4 / 43), Salmonella 2.33% (1 / 43). (2) based on clinical manifestations and isolation and identification. Three strains of Escherichia coli were randomly selected from the materials from which the disease was diagnosed as Escherichia coli to test the pathogenicity of mice. All the 3 mice died at 18 h after inoculation, which indicated that the pathogenicity of the isolated strains was very strong. The three strains of Escherichia coli were identified as O 141 (2 strains, pathogenicity) and O 20 (1 strain, not pathogenic). All of the three mice inoculated with Salmonella died at about 13 h after inoculation, indicating that the isolated strains had strong pathogenicity, and the serum type of Salmonella suspectus was identified as Group B Salmonella typhimurium (S.Typhimurium), the serotype was O _ 4. The mental state and diet desire of mice inoculated with O21 and Proteus did not change obviously, and there was no death, which indicated that the virulence of the isolated strain was very weak or no pathogenicity. The genomic sequences of Salmonella suspectus and Proteus were sequenced. By NCBI Blast gene alignment, the homology between the alignment sequence and the target sequence was 99%, which was determined to be Salmonella and Proteus. (3) the results of drug sensitivity test showed that, Escherichia coli was sensitive to gentamicin, ciprofloxacin, neomycin, kanamycin, streptomycin and enrofloxacin, and was partially resistant to tetracycline and ampicillin sodium. Salmonella was sensitive to ceftriaxone sodium and resistant to gentamicin tetracycline ampicillin neomycin kanamycin streptomycin and enrofloxacin. Proteus is sensitive to gentamicin, ciprofloxacin, kanamycin, streptomycin, enrofloxacin, and resistant to ceftriaxone sodium, tetracycline, ampicillin sodium. To sum up, gentamicin, kanamycin and neomycin can be used to treat diarrhea caused by Escherichia coli in piglets, and ceftriaxone sodium can be used to treat diarrhea caused by salmonella. Among the pathogens causing diarrhea in piglets, Escherichia coli is the most important one. Although the isolation rate of Salmonella is low, the isolated strain is Salmonella typhimurium, and the isolates are resistant to most antibiotics.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S858.28

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