title: Improvement of mannitol-yolk-polymyxin B agar by supplementing with trimethoprim for quantitative detection of Bacillus cereus in foods.
abstract: Mannitol-yolk-polymyxin B agar (MYPA) was modified by supplementation with trimethoprim. The ability of the supplemented medium to select for and recover Bacillus cereus from pure cultures and food samples with high background microflora was compared with MYPA. For  evaluation of the modified MYPA (mMYPA) in food samples with high background microflora, B. cereus was experimentally spiked into red pepper powder, fermented soybean paste, vegetable salad, and radish sprouts, and then it was recovered on MYPA and mMYPA for comparison. In all food  samples, there was no difference in recoverability (P > 0.05) between mMYPA (red pepper powder, 3.34 ± 0.24 log CFU/g; fermented soybean paste, 3.52 ± 0.47 log CFU/g; vegetable salad, 3.51 ± 0.23 log CFU/g; radish sprouts, 3.32 ± 0.40 log CFU/g) and MYPA  (red pepper powder, 3.18 ± 0.20 log CFU/g; fermented soybean paste, 3.33 ± 0.43 log CFU/g; vegetable salad, 3.36 ± 0.19 log CFU/g; radish sprouts, 3.33 ± 0.31 log CFU/g). However, mMYPA exhibited better selectivity than MYPA, because additional trimethoprim made  the differentiation of suspected colonies easier by inhibiting competing flora. The addition of trimethoprim to conventional media could be a useful option to improve selectivity in foods with high background microflora.
authors.affiliation: Center for Food Safety and Animal Health, College of Veterinary Medicine, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, The Republic of Korea. bracstu3@konkuk.ac.kr
authors.forename: Jung-Whan
authors.initials: JW
authors.lastname: Chon
authors.forename: Ji-Yeon
authors.initials: JY
authors.lastname: Hyeon
authors.forename: Jun-Ho
authors.initials: JH
authors.lastname: Park
authors.forename: Kwang-Young
authors.initials: KY
authors.lastname: Song
authors.forename: Jong-Hyun
authors.initials: JH
authors.lastname: Kim
authors.forename: Kun-Ho
authors.initials: KH
authors.lastname: Seo
mesh_terms: D000362:Agar / Q000737:chemistry; D001409:Bacillus cereus / Q000302:isolation & purification*; D015169:Colony Count, Microbial / Q000295:instrumentation / Q000379:methods*; D003257:Consumer Product Safety; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D014295:Trimethoprim / Q000494:pharmacology
chemical_list: D000362:Agar; D014295:Trimethoprim