Prevalence, Genetic Diversity, and Antibiotic Susceptibility of Bacillus cereus Strains Isolated from Rice and Cereals Collected in Korea

• Published in: Journal of food protection 2009-03, Vol.72 (3), p.612-617
• Main Authors: Park, Yong-Bae, Kim, Jung-Beom, Shin, Sang-Woon, Kim, Jong-Chan, Cho, Seung-Hak, Lee, Bok-Kwon, Ahn, Juhee, Kim, Jae-Myung, Deog-Hwan Oh
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; Antibiotics; Bacillus cereus; Bacillus cereus - drug effects; Bacillus cereus - genetics; Bacillus cereus - isolation & purification; Bacillus cereus - metabolism; Bacterial infections; Barley; Biological and medical sciences; case studies; Cereal and baking product industries; Cereals; Colony Count, Microbial; Consumer Product Safety; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Dose-Response Relationship, Drug; Drug Resistance, Bacterial; Edible Grain - microbiology; Electrophoresis, Gel, Pulsed-Field; Enterotoxins - biosynthesis; Enterotoxins - genetics; Food contamination & poisoning; Food Contamination - analysis; Food industries; Food Microbiology; Food safety; Fundamental and applied biological sciences. Psychology; Genes; Genetic diversity; Genetic Variation; grain crops; Hordeum vulgare; Humans; Korea; Microbial Sensitivity Tests; Microorganisms; Oryza - microbiology; Oryza sativa; Penicillin; Population studies; Prevalence; Rice; Studies; Toxins
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028x-72.3.612

Incidence and properties of Bacillus cereus strains naturally present in cereals were evaluated by phenotypic characterization, antibiotic susceptibility testing, and pulsed-field gel electrophoresis. Of 293 cereal samples tested, 73 (25%) contained B. cereus strains. Incidence of B. cereus isolates varied with respect to sample; they were found in 15 (37%) of 83 brown rice samples, 23 (37%) of 63 glutinous rice samples, 16 (21%) of 76 barley samples, and 19 (27%) of 71 Job's tears samples. All B. cereus isolates from cereals were positive for diarrheal toxin genes. The isolates were susceptible to most of the antibiotics tested, but they were highly resistant to ampicillin, cefepime, oxacillin, and penicillin. Of the genes assayed by the PCR technique, a high frequency of nheA (99%) and hblDC (84%) was found in the genomic DNA of cereal-associated isolates, whereas cytK was less common (55%). From the strains carrying the hblDC genes, 93% produced enterotoxin HBL. B. cereus isolates did not have significant genetic homology. The genetic diversity and toxic potential differ among the strains isolated from cereals. These results provide important information on toxin gene profiles of cereal-associated B. cereus for population studies.