title: Characterization of Bacillus cereus isolates from local dairy farms in China.
abstract: Bacillus cereus is an important opportunistic foodborne pathogen. In the present work, a total of 306 milk and environmental samples were collected from 10 local dairy farms in Beijing, China. Of the 92 B. cereus-like isolates, 88 and 4 belonged to B. cereus and B. thuringiensis, respectively. The prevalence of B. cereus isolates in bedding, feces, feed, liquid manure and raw milk was 93.3%, 78.9%, 41.2%, 100.0% and 9.8%, respectively. Three main toxin genes nhe, hbl and ces were detected with rates of 100.0%, 78.3% and 1.1%, but no strain harbored cytK1 The production of Nhe, Hbl and cereulide could be confirmed by specific monoclonal antibodies-based enzyme immunoassays in 94.6%, 70.7% and 1.1% of all isolates, respectively. Cytotoxicity tests were used to further corroborate the results of genetic and protein-based assays; 91.3% of the isolates showed cytotoxicity to Vero cells. All isolates were tested for antimicrobial resistance against 17 antibiotics. All isolates were resistant to lincomycin, retapamulin, tiamulin and valnemulin, while two strains were susceptible to ampicillin and ceftiofur. A total of 16 isolated strains were resistant to tetracycline. Since spores of B. cereus are not inactivated during manufacturing of most milk products, contamination of milk with B. cereus on the farm level may represent a potential hazard, particularly with respect to emetic toxin-producing strains.
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
authors.forename: Yifang
authors.initials: Y
authors.lastname: Cui
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
authors.forename: Xiaoye
authors.initials: X
authors.lastname: Liu
authors.affiliation: Institute of Food Safety, Department of Veterinary Sciences, Ludwig-Maximilians-University Munich, Oberschleißheim 85764, Germany.
authors.forename: Richard
authors.initials: R
authors.lastname: Dietrich
authors.affiliation: Institute of Food Safety, Department of Veterinary Sciences, Ludwig-Maximilians-University Munich, Oberschleißheim 85764, Germany.
authors.forename: Erwin
authors.initials: E
authors.lastname: Märtlbauer
authors.affiliation: College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Cao
authors.affiliation: College of Veterinary Medicine, China Agricultural University, Beijing 100193, China dingsy@cau.edu.cn.
authors.forename: Shuangyang
authors.initials: S
authors.lastname: Ding
authors.affiliation: Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
authors.forename: Kui
authors.initials: K
authors.lastname: Zhu
mesh_terms: D000821:Animal Feed / Q000382:microbiology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001409:Bacillus cereus / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification* / Q000502:physiology*; D001413:Bacillus thuringiensis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D001426:Bacterial Proteins / Q000235:genetics / Q000633:toxicity; D001427:Bacterial Toxins / Q000235:genetics / Q000633:toxicity; D002417:Cattle; D002522:Chlorocebus aethiops; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000235:genetics; D003612:Dairying; D000072480:Farms; D005243:Feces / Q000382:microbiology; D005516:Food Microbiology; D006460:Hemolysin Proteins / Q000235:genetics / Q000633:toxicity; D008372:Manure / Q000382:microbiology; D008892:Milk / Q000382:microbiology*; D066256:Raw Foods / Q000382:microbiology; D013171:Spores, Bacterial; D014709:Vero Cells
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004269:DNA, Bacterial; D006460:Hemolysin Proteins; D008372:Manure; C083961:hemolysin BL protein, Bacillus
keywords: Bacillus cereus; antimicrobial susceptibility; dairy; toxin