Objective To investigate the distribution of Bacillus cereus isolated from Hainan rice noodles in Haikou area and detect the virulence genes, we provide the basis for the formulation of prevention and control strategy of Bacillus cereus contamination in Haikou.
Methods Totally 219 samples of Hainan rice noodles, collected from four types of outlets from four districts in Haikou city, were used for B. cereus detection. Ten virulence genes of Bacillus cereus were detected by PCR method. The statistical difference of the detection rate and virulence gene carrying rate of Bacillus cereus in Hainan rice noodles from different regions and different point of sale sources were analyzed by the chi-square test.
Results Totally 137 strains of B. cereus were isolated from 219 samples and the positive rate was 62.6%(137/219). The positive rate of B. cereus from Meilan district was the highest, 77.1%(81/105), and that from Longhua district was the lowest, 44.3%(27/61). The difference of positive rate among four districts was statistically significant. The comparison between any two districts showed that the positive rate of Meilan district was significantly higher than that of the other three districts. Among the four types of outlets, the positive rate of mobile dining car was the highest 76.9%(20/26), and that of large or medium-sized hotels was the lowest, 23.1%(9/39). The difference of positive rate among four types of outlets was statistically significant. The comparison between any two showed that the positive rate of large or medium-sized hotels was significantly lower than that of the other three types of outlets, and so is that of the difference in each district. However, the positive rate of B. cereus isolated from Hainan rice noodles from small restaurants is significantly higher than that from the other three types of outlets, especially in Meilan district. Non-hemolytic enterotoxin gene and gene entFM were the main virulence genes in Haikou area. The difference of carrying rate among four districts or four outlets were not statistically significant, except that the genes of hblA and hblD in Meilan and Longhua districts were higher than that in other areas.
Conclusion Hainan rice noodles sold in Haikou area were seriously contaminated by B. cereus, especially from small restaurants in Meilan district, which should be paid great attention and food safety supervision should be strengthened.
摘要： 目的 调查海口市市售海南粉中蜡样芽胞杆菌污染情况及毒力基因分布, 为海口市市售海南粉中蜡样芽胞杆菌污染防控策略制定提供依据。 方法 对采集自海口市四个区四类销售点的219份海南粉样品进行蜡样芽胞杆菌的分离鉴定, 并用普通PCR方法检测菌株的10种毒力基因, 采用统计学方法分析不同地区、不同销售点来源的海南粉中蜡样芽胞杆菌的检出率和毒力基因携带率差异。 结果 海口市售海南粉的蜡样芽胞杆菌总检出率为62.6% (137/219) 。美兰区检出率最高, 为77.1% (81/105), 龙华区最低, 为44.3% (27/61) 。四类销售点中流动餐车检出率最高, 为76.9% (20/26), 大中型饭店最低, 为23.1% (9/39) 。非溶血性肠毒素基因和 entFM 基因为研究菌株携带的主要毒力基因, 美兰区和龙华区菌株的 hblA 和 hblD 基因携带率高于其他两区, 其余基因在不同地区间无统计学差异; 不同销售点的菌株毒力基因携带率无统计学差异显著性。 结论 海口市售海南粉蜡样芽胞杆菌污染较为严重, 在美兰区和小餐馆尤为严重, 应加大力度进行食品安全监管。