关键词: 乳品, 蜡样芽胞杆菌, 耐药性, 毒力基因, 分子分型

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