两种选择性培养基HE、CAS检测沙门菌效果的比较  

Comparing the effectiveness of two selective media HE and CAS for the detection of Salmonella in foods

作　　者：闫琳[1] 王晓英[1] 郭云昌[1] 裴晓燕[1] 余东敏[1] 

机构地区：[1]中国疾病预防控制中心营养与食品安全所,北京100021

出　　处：《中国食品卫生杂志》2011年第2期118-122,共5页Chinese Journal of Food Hygiene

基　　金：国家自然科学基金(30571575);科技部科研院所技术开发研究专项(2009EG150293)

摘　　要：目的比较两种沙门菌选择性培养基HE和CAS在食物样本检测中的敏感性、准确性和时效性。方法观察典型沙门菌和非沙门菌在两种选择培养基上的生长状况和菌落形态。通过人工染菌实验,比较两种选择性培养基分离沙门菌的检测效果。采集16份市售整鸡样本,进一步比较两种培养基沙门菌的阳性检出率。结果沙门菌在HE平板上为绿色菌落,大多有黑心;在CAS平板上为紫色菌落。含菌量为10 CFU/25 g鸡肉样本,经SC增菌液增菌培养8 h,可用CAS检出沙门菌;而采用HE则需增菌18 h才可检出。16份整鸡样本,增菌8、12和18 h,采用CAS的阳性检出率分别为43.75%、31.25%和37.5%,相应时间下采用HE的阳性检出率分别为18.75%、25%和18.75%。8份新鲜整鸡样本,检出4份阳性;8份冷冻整鸡样本,检出3份阳性。结论 CAS选择性平板可抑制大多杂菌生长,沙门菌在其上菌落形态较易鉴别。CAS分离沙门菌的检出时限和检测灵敏度都明显优于HE,建议在食物样本检测沙门菌时应首选CAS。Objective To compare the effectiveness of two kinds of selective media HE（hektoen enteric agar） and CAS（CHROM agar Salmonella medium） on the detection of Salmonella in food samples.Methods The growth status and the morphology of Salmonella and non-Salmonella colonies on HE and CAS were observed.Twenty five grams of chicken meat were distributed in 225 ml of SC（Selenite Cystine Broth） and Salmonella standard strain CMCC 50041 was used to perform artificially-contaminated experiments.The final concentration of Salmonella for each sample was 0,1,10,102,103,104,105 and 106 CFU per 25g poultry respectively.All samples were incubated at 37 ℃ for 0,4,8,12 and 18 h.One loop from each culture medium taken at different incubation time was streaked on HE or CAS plates.The suspected Salmonella colonies were confirmed by API 20E.The sensitivity of two media on the isolation of Salmonella was compared.Sixteen retail whole chicken samples collected from markets in Beijing were examined by HE and CAS plates after enriched at 37 ℃ for 8,12 and 18 h in SC,and the positive rates by HE and CAS plates were compared.Results The colony of Salmonella spp.on HE is green,most are black in the center,but that on CAS is mauve.Salmonella could be isolated by CAS from poultry samples containing at least 10 CFU per 25 g samples after being enriched for 8h in SC;but 18h of enrichment was needed for achieving the same result with HE.The positive rates of Salmonella for 16 whole chicken samples were 43.75%,31.25% and 37.5% by CAS after enrichment for 8,12 and 18h respectively;and the positive rate were 18.75%,25% and 18.75% by HE,correspondingly.Salmonella in 4 of 8 fresh whole chicken samples were positive,whereas in 3 of 8 frozen whole chicken samples were positive.Conclusion The growth of most non-Salmonella could be restrained by the selective medium CAS.The morphology of Salmonella colonies could be distinguished easily from other bacteria.The time limit and sensitivity of detection for Salmonella with CAS are significantly b

关 键 词：HE培养基 CAS培养基 沙门菌 比较 

分 类 号：R155.5[医药卫生—营养与食品卫生学]