高特异性单核细胞增生李斯特菌显色培养基性能研究

Research on the chromogenic medium efficiency of high specific Listeria monocytogenes

目的研究不同分离培养基对纯菌及实际样品中单核细胞增生李斯特菌的分离效果。方法根据GB 4789.30—2010单核细胞增生李斯特菌检验方法,比较了本实验室制备的单核细胞增生李斯特菌显色培养基(L.MONO)、PALCAM及4种商品化显色培养基(CHROMagar、厂家Ⅰ、厂家Ⅱ和厂家Ⅲ)的性能。结果 6种培养基的选择性之间差异有统计学意义(P<0.01),L.MONO和Ⅲ最好,其次为CHROMagar和厂家Ⅰ,厂家Ⅱ和PALCAM较差。49份样品阳性率为28.57%,L.MONO和厂家Ⅲ检出阳性符合率为100%,无假阳性和假阴性;CHROMagar阳性符合率为92.9%,厂家Ⅰ和厂家Ⅱ阳性符合率最差,PALCAM阳性样品完全检出,但有太多假阳性。结论 L.MONO性能达到甚至更优于CHROMagar,采用特异性更高的水不溶性显色剂可有效避免非特异性菌β葡萄糖苷酶的表达及脂肪沉淀环扩散引起的干扰和假阳性,也能有效解决现有显色培养基制备中配套试剂混匀困难的问题,是一种更为高效的单核细胞增生李斯特菌显色培养基。

Objective To evaluate the performance of different isolation medium in Listeria monocytogenes of pure bacteria and actual samples. Methods The performance of L. MONO chromogenic culture medium that made by our lab was compared with PALCAM and 4 commercial chromogenic media（ CHROMagar,manufacturer Ⅰ,Ⅱ,Ⅲ） according to GB 4789. 30—2010 Food microbiological examination： Listeria monocytogenes. Results The selectivity difference of the 6 selective media was statistical significance（ P 0. 01）. L. MONO and Ⅲ were the best,followed by CHROMagar and Ⅰ,Ⅱand PALCAM were poor. The total positive rate of the 49 samples was 28. 57%. The positive rate of L. MONO and Ⅲwere all 100%,with no false positive and false negative. The positive rate of CHROMagar showed 92. 9%. Ⅰand Ⅱ had the worst positive rate. There were too many false positives of PALCAM although true positive samples were completely detected. Conclusion The performance of L. MONO was achieve even better than CHROMagar. By using the high specificity of water insoluble chromogenic agent,it can effectively avoid interference and false positive caused by nonspecific β glucosidase expression and lecithin halo spread. It also can effectively solve the difficulty in mixing the corollary reagent of the existing chromogenic media. L. MONO is a more efficient Listeria monocytogenes chromogenic medium.