摘要
目的为了准确计数生鲜肉中的沙门氏菌的数量,为微生物危险性评估提供精确的数据支持,探索一种实用性、准确性和选择性的沙门氏菌计数方法.方法将污染不同数量沙门氏菌的样品分别稀释,同时用平板计数法和MPN法分别计数,比对两方法的准确度、灵敏度和可操作性.平板计数选用CHROMagar显色培养基平板和XLD琼脂平板作分离平板,挑取可疑菌落经鉴定后,计算沙门氏菌数.MPN法选用TTB、MM和SC增菌液分别于(36±1)℃、(42±1)℃增菌后,接种CHROMaagar显色培养基平板和XLD琼脂平板,挑取可疑菌落鉴定后查MPN表.结果样品中污染沙门氏菌量在1～500 cfu/g时,平板计数法不能将沙门氏菌很好地区分;MPN法采用SC增菌液(42±1)℃培养效果最好,检出限10 cfu/g,检测值和理论值(在500 cfu/g)的符合率为92.0%.结论MPN法无论从可操作性或是检出的灵敏度都要优于平板计数法.
Objective To find an accurate, practical, precise and selective counting method of Salmonella in fresh meat specimen and provide scientific basis of microbial risk assessment. Methods Diluting the samples that polluted with different numbers of Salmonella species, the plate count method and MPN method were adopted to count the value, made comparison of these two methods on accuracy, sensitivity and practicability. Choose CHROMagar Salmonella plate and XLD agar plate as separating plate in plate count method, the total number of definite Salmonella clones on each plate was counted after identifying the suspected colonies. At the same time, select the TTB, MM and SC enriched broth to culture the polluted sample at 36 ± 1 ℃ and 42 ± 1 ℃ in MPN method respectively, inoculate the enriched broth to GHROMagar Salmonella plate and XLD agar plate,and the total number of definite Salmonella within 1 cfu/g to 500 cfu/g in plate count method. Results The cul- ture effect of SC enrichment broth was the best at 42 ± 1 ℃ in MPN method, its lowest detection limit was 10cfu/g and the coincidence rate of the examination value and theory value （500cfu/g） was 92.0%. Conclusion The MPN method is better than the plate counting method both in sensitivity and applicability.
出处
《实用预防医学》
CAS
2005年第5期1065-1066,共2页
Practical Preventive Medicine
关键词
沙门氏菌
定量
平板计数
MPN法
Salmonella
Quantitative
Plate count method
MPN method
