BACARA® 2和RAPID'B. cereus®琼脂与甘露醇卵黄多粘菌素（MYP）琼脂用于检测蜡样芽孢杆菌属菌株的计数比较研究

Enumeration Comparison Study of BACARA® 2 and RAPID'B. cereus® Agars to Mannitol-Egg Yolk-Polymyxin (MYP) Agar for Detection of Bacillus cereus Group Strains.

作者信息

Cao Guojie, Miller Jennifer, Wang Shizhen Steven, Tallent Sandra

机构信息

U.S. Food and Drug Administration, Human Food Program, College Park, MD 20740, USA.

出版信息

J AOAC Int. 2025 Sep 1;108(5):732-752. doi: 10.1093/jaoacint/qsaf059.

DOI:10.1093/jaoacint/qsaf059

PMID:40674574

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC12418170/

Abstract

BACKGROUND

The Bacillus cereus group (B. cereus sensu lato) is a group of spore-forming strains. B. cereus group is a human pathogen associated with foodborne outbreaks with symptoms of diarrhea and emesis.

OBJECTIVE

This study evaluates the performance of BACARA® 2 (BAC2) and RAPID'B. cereus® (RAPID) agars compared to mannitol-egg yolk-polymyxin (MYP) agars and the original BACARA® (BAC) media to detect and enumerate the B. cereus group in pure culture and foods.

METHODS

We incorporated five food types to include liquid milk, whey powder, mashed potatoes, rice, and tea bags. For each food matrix, there were five test portions per level inoculum prepared (low, medium, and high), and a negative control. Individual test portions were diluted 1:10 in Butterfield's phosphate buffer (BPB) and 0.1 mL of the dilutions were inoculated on BAC2, RAPID, and MYP agars. In-house R script was applied to conduct statistical analysis to compare medium performance in food adulteration tests.

RESULTS

Inclusivity testing determined that all six B. cytotoxicus strains grew on BAC2, RAPID, and MYP but only one strain grew on BAC after 24 h incubation. RAPID had similar results as BAC2 in single-colony tests. In food tests, relative level of detection (RLOD) values indicated MYP was more sensitive for detecting B. cereus strains than BAC2 and RAPID, which is a result of B. cytotoxicus strains in mashed potato and whey powder needing an additional 24-hour incubation to exhibit typical morphology on BAC2 and RAPID.

CONCLUSION

Our study demonstrated the use of BAC2 and/or RAPID agar will improve the performance of the U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM) B. cereus method, particularly for the detection of B. cytotoxicus. Importantly, the use of BAC2 and/or RAPID will decrease the time to detect viable B. cereus strains without additional confirmation steps compared to MYP.

HIGHLIGHTS

For improved isolation and identification of B. cereus group in foods, we propose the use of BAC2 or RAPID as optional agars, along with MYP.

摘要

背景

蜡样芽孢杆菌群（蜡样芽孢杆菌广义）是一组形成芽孢的菌株。蜡样芽孢杆菌群是一种与食源性疾病暴发相关的人类病原体，会引起腹泻和呕吐症状。

目的

本研究评估了BACARA® 2（BAC2）和RAPID'B. cereus®（RAPID）琼脂与甘露醇卵黄多粘菌素（MYP）琼脂以及原始BACARA®（BAC）培养基相比，在纯培养物和食品中检测和计数蜡样芽孢杆菌群的性能。

方法

我们纳入了五种食品类型，包括液态奶、乳清粉、土豆泥、米饭和茶包。对于每种食品基质，每个接种水平准备五个测试部分（低、中、高），并设置一个阴性对照。将各个测试部分在巴特菲尔德磷酸盐缓冲液（BPB）中按1:10稀释，取0.1 mL稀释液接种到BAC2、RAPID和MYP琼脂上。使用内部R脚本进行统计分析，以比较食品掺假测试中培养基的性能。

结果

包容性测试确定，所有六种细胞毒素蜡样芽孢杆菌菌株在BAC2、RAPID和MYP上均生长，但在培养24小时后，只有一种菌株在BAC上生长。在单菌落测试中，RAPID与BAC2的结果相似。在食品测试中，相对检测水平（RLOD）值表明，MYP比BAC2和RAPID对检测蜡样芽孢杆菌菌株更敏感，这是因为土豆泥和乳清粉中的细胞毒素蜡样芽孢杆菌菌株在BAC2和RAPID上需要额外培养24小时才能呈现典型形态。