Prevalence, molecular characterization, and antibiotic susceptibility of Bacillus cereus isolated from dairy products in China

摘要

This study was conducted to reveal the prevalence,molecular characterization, and antibiotic susceptibilityof Bacillus cereus isolated from dairy products includingpowdered infant formula, raw milk, pasteurized milk,ultra-high-temperature milk, and cheese. Five hundredsamples collected from 5 provinces in China wereanalyzed in overall experiments. Multilocus sequencetyping, distribution of toxin genes, and antibiotic susceptibilityof the isolates were analyzed. Fifty-four B.cereus strains were detected; of these, 13 isolates (26%)were from raw milk, 12 isolates (12%) from pasteurizedmilk, 10 isolates (10%) from cheese, 12 isolates(8%) from ultra-high-temperature milk, and 7 isolates(7%) from powdered infant formula. These isolateswere divided into 24 sequence types (ST); among them,ST24, ST26, ST82, ST142, ST377, ST857, and ST1046were the main dominant ST. The results of detectionof toxin genes (hblA, hblC, hblD, nheA, nheB, nheC,cytK, entFM, bceT, hlyII, and cesB) showed that 94.4%isolates carried nheABC genes, whereas only 11.1%of the isolates contained the hblACD gene cluster. Inaddition, detection rates of cytK, bceT, entFM, hlyII,and cesB genes were 75.9, 77.8, 85.2, 53.7, and 11.1%,respectively. The antibiotic susceptibility test indicatedthat most of B. cereus isolates were resistant to ampicillin,penicillin, cefepime, cephalothin, and oxacillin,and were susceptible to gentamicin, chloramphenicol,imipenem, tetracycline, ciprofloxacin, trimethoprimsulfamethoxazole,erythromycin, kanamycin, and cefotetan.Therefore, this study revealed the prevalence andcharacteristics of B. cereus isolated from dairy productsin China, indicating the potential risk and contributingto the effective prevention and control of this pathogen.