致犊牛脑炎E.coli S9922生物学特性及对不同环境消毒剂抵抗力的测定

Determination of biological characteristics and resistance to different environmental disinfectants of calf encephalitis E.coli S9922

致犊牛脑炎大肠杆菌S9922是从7日龄以内死亡犊牛大脑中分离出的一株肠外致病性大肠杆菌Extrain?testinal pathogenic Escherichia coli(ExPEC),引发犊牛的脑炎及腹泻。为研究E.coliS9922的生物学特性以及对外界消毒剂的抵抗作用,试验对E.coli S9922进行了生化鉴定、血清学鉴定、溶血性试验、药敏试验和LD50的测定,同时测定了E.coli S9922对环境消毒剂稀戊二醛溶液、二氯异氰尿酸钠粉剂、苯扎溴铵溶液和聚维酮碘溶液的抵抗力。结果表明,E.coli S9922 V-P试验为阴性,吲哚试验为阳性,能发酵甘露醇、木糖、葡萄糖、鼠李糖、麦芽糖,且均能产酸不产气;在牛大肠杆菌27种常见血清型中,并未检测到E.coli S9922的血清型;在5%的兔血和5%绵羊鲜血平板上未见溶血圈;E.coli S9922对氯霉素、四环素、庆大霉素、环丙沙星、氨苄青霉素、卡那霉素,左氧氟沙星、头孢噻肟、青霉素耐药,对多粘菌素b和大观霉素不耐药,且具有多重耐药特性;LD50计算结果为107.238mg/kg,表明E.coli S9922是一株强毒株;在高浓度的消毒剂作用下,均能杀灭该菌,而在低浓度消毒剂作用下,稀戊二醛溶液和苯扎溴铵溶液比聚维酮碘溶液和二氯异氰尿酸钠的消毒效果好。研究结果可为肠外致病性大肠杆菌的研究提供试验数据以及对畜舍内环境消毒提供理论指导。

Extraintestinal pathogenic Escherichia coli(ExPEC)S9922 was isolated from the brains of calves that died within seven days of age which can cause encephalitis and diarrhea in calves.In order to study the biological characteristics of E.coli S9922 and its resistance to external disinfectants,biochemical identification,serological identification,hemolytic test,drug susceptibility test and LD50 determination of E.coli 9922 were performed.The resistance of E.coli S9922 to environmental disinfectant dilute glutaraldehyde solution,sodium dichloroisocyanurate powder,benzalkonium bromide solution and povidone iodine solution were also determined.The results showed that E.coli S9922 v-p test was negative and indoles test was positive,which could ferment mannitol,xylose,glucose,rhamnose and maltose,and all could produce acid but no gas.Among the 27 common serotypes of bovine E.coli,the serotype of E.coli S9922 was not detected;No hemolytic circles were found on 5%rabbit blood and 5%sheep blood plates.E.coli S9922 was resistant to chloramphenicol,tetracycline,gentamicin,ciprofloxacin,ampicillin,kanamycin,levo‐floxacin,cefotaxime,penicillin,and was not resistant to polymyxin b and macromycin,and had multi-drug characteristics.The LD50 of E.coli S9922 was 106.24mg/kg,indicating that it was a highly virulent strain.E.coli S9922 could be killed with the high concentration disinfectant,and under the low concentration disinfectant,dilute glutaraldehyde solution and benzene Zalbromine solution had a better disinfecting effect than povidone iodine solution and sodium dichloroisocyanurate.The results can provide experimental data for the study of ExPEC and theoretical guidance for the disinfection of the environment in the livestock house.