猪源艰难梭菌的分离鉴定及特性分析

ISOLATION AND IDENTIFICATION OF A CLOSTRIDIUM DIFFICILE FROM PIGS

为了解河南省规模化猪场猪源艰难梭菌的流行、耐药以及毒素基因携带情况,收集来自豫西地区5个养殖场中疑似艰难梭菌感染(clostridium difficile infection,CDI)猪的粪便标本(n=41)。采用厌氧培养法,用艰难梭菌选择性培养基环丝氨酸-头孢西丁-果糖琼脂(cycloserine-cefoxitin-fructose agar,CCFA)完成分离培养。采用表型培养法进行菌株分离和鉴定,以多重PCR同时鉴定菌株并检测tcdA和tcdB毒素基因及二元毒素编码基因cdtA和cdtB。采用E-test法检测艰难梭菌对常用抗生素的最低抑菌浓度(minimal inhibitory concentration,MIC)值并判定菌株对药物的敏感性。结果从分离的41份样本中,经染色镜检及PCR鉴定,分离出符合艰难梭菌生长特性的菌株1株。药敏结果显示分离菌株对万古霉素和甲硝唑呈现高度敏感,对氟喹诺酮类药物以及四环素等表现出不同程度的耐药。艰难梭菌的研究大多集中在人源方面,本研究首次在河南省规模化养猪场中分离出艰难梭菌,对所分离菌株进行毒素基因检测,毒素A、B呈阳性,而无二元毒素基因。分离的猪源艰难梭菌对红霉素、万古霉素、甲硝唑、利福平均呈现高度敏感,对克林霉素、阿莫西林、左氧氟沙星、利奈唑酮和青霉素呈现不同程度的耐药。

Total 41 fecal specimens were collected from pigs suspected of Clostridium difficile infection for bacterial isolation and identification. One C. difficile isolate was obtained and identified by staining microscopy and PCR. This isolate was analyzed by 5-plex PCR to determine the presence of toxin genes. The results showed that this isolate was positive for toxins A and B but no binary toxin gene.Drug testing showed that this isolate was highly susceptible to erythromycin, vancomycin, metronidazole and rifampicin and varying resistant to clindamycin, amoxicillin, levofloxacin, linazolone and penicillin. Most of the previous studies on C. difficile have focused on human infection. This study was the first time to isolate C. difficile from large-scale pig farms in Henan province.