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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 study the isolation of Listeria monocytogenes from pure and actual samples with different isolation media. Methods According to the test method of Listeria monocytogenes GB 4789.30-2010, Listeria monocytogenes color medium (L.MONO), PALCAM and four commercially available chromogenic medium (CHROMagar, Factory I, Factory II and Factory III). Results There was a significant difference in the selectivity between the six media (P <0.01). L.MONO and Ⅲ were the best, followed by CHROMagar and manufacturer Ⅰ, and those of manufacturer Ⅱ and PALCAM were poor. The positive rate of the 49 samples was 28.57%, the positive coincidence rate of L.mono and the manufacturer Ⅲ was 100%, no false positive and false negative; CHROMagar positive coincidence rate was 92.9%, the positive coincidence rate of manufacturer I and manufacturer II was the worst, PALCAM positive samples were completely detected, but there were too many false positives. Conclusions L.MONO can achieve even better performance than CHROMagar. The use of a more specific water-insoluble chromogenic reagent can effectively prevent the expression of non-specific bacterial β-glucosidase and the interference and false positive caused by the diffusion of fat deposition rings. Solving the problem of difficult mixing in the reagent preparation of the existing chromogenic medium is a more efficient Listeria monocytogenes chromogenic medium.