Abstract: To investigate the virulence factors, molecular characteristics and drug resistance of Bacillus cereus from dairy sources, 122 strains of Bacillus cereus isolated from dairy products were collected from 2016 to 2019. The resistances of the strains to 9 antibiotics including chloromycetin, gentamicin, et al were determined by paper diffusion method (K-B paper method). The virulence factors and molecular characters were detected by polymerase chain reaction and pulsed field gel electrophoresis (PFGE). The results showed that 122 strains of Bacillus cereus were sensitive to chloramphenicol, gentamicin and amikacin. The mediating rates for erythromycin, clindamycin and ciprofloxacin were 5.74%, 4.92% and 0.82%, respectively. The resistance was 9.84% for cotrimoxazole, 8.20% for tetracycline and 4.10% for rifampicin. The non-hemolytic enterotoxin genes nheA, nheB and enterotoxin FM gene entFM were detected in 122 Bacillus cereus strains, and the detection rates of nheC, bceT, cytK, hblA, hblC, hblD, ces and EM1 were 99.18%, 37.70%, 31.15%, 29.51%, 24.59%, 8.20%, 6.56% and 6.56%, respectively. 122 strains of Bacillus cereus were divided into 15 clusters, and there was no obvious dominant type. The milk isolates of Bacillus cereus collected from 2016 to 2019 carried a variety of virulent genes. Less than 10% of the isolates were resistant to cotrimoxazole, tetracycline and rifampicin, and showed a variety of bands of PFGE, which provided reference for early prevention and treatment of foodborne diseases caused by Bacillus cereus.

Key words: dairy products, Bacillus cereus, drug resistance, virulence genes, molecular typing

摘要： 为了解乳品来源蜡样芽胞杆菌携带的毒力因子、分子特征及耐药性，对2016—2019年分离自乳品的122株蜡样芽胞杆菌，采用纸片扩散法（K-B纸片法）测定了分离株对氯霉素、庆大霉素等9种抗生素的耐药性，使用聚合酶链式反应法检测了菌株携带的毒力因子，同时采用脉冲场凝胶电泳（pulsed field gel electrophoresis，PFGE）检测分离株的分子特征。结果表明，122株蜡样芽胞杆菌均对氯霉素、庆大霉素、阿米卡星敏感；对红霉素、克林霉素和环丙沙星的中介率分别为5.74%、4.92%和0.82%， 9.84%的菌株对复方新诺明具有耐药性，8.20%的菌株对四环素具有耐药性，4.10%的菌株对利福平具有耐药性。122株蜡样芽孢杆菌都检出了蜡样芽孢杆菌的非溶血型肠毒素基因nheA、nheB及肠毒素FM基因entFM；nheC、bceT、cytK、hblA、hblC、hblD、ces和EM1基因的检出率分别为99.18%、37.70%、31.15%、29.51%、24.59%、8.20%、、6.56%和6.56%。122株蜡样芽胞杆菌被分成15簇，未见明显的优势带型。由此可见，2016—2019年收集的蜡样芽胞杆菌乳品分离株携带多种毒力基因，约10%的菌株对复方新诺明、四环素、利福平等具有耐药性，PFGE呈现多种带型，为蜡样芽孢杆菌引起的食源性疾病的预警、预防和治疗提供参考。

关键词: 乳品, 蜡样芽胞杆菌, 耐药性, 毒力基因, 分子分型