美国食品药品局细菌分析手册（BAM）第10章：单核细胞增生李斯特氏菌（2022年4月版）BAM Chapter 10 Detection of Listeria monocytogenes in Foods and Environmental Samples, and Enumeration of Listeria monocytogenes in Foods

The genus Listeria contains 6 species: L. monocytogenes, L. innocua, L. seeligeri, L. welshimeri, L. ivanovii, and L. grayi (Table 1). L. grayi (28, 40) and L. ivanovii (13, 27) each contain two subspecies, which do not need to be specified in this analysis. A taxonomic review of the genus by Rocourt (41) in 1999 updated the previous reviews (11, 43). In recent years, many new species were proposed. However, these new species are not widely adopted and the number of type strains for the newly proposed species are very limited. L. ivanovii and L. monocytogenes are pathogenic for mice and other animals. However, only L. monocytogenes is commonly associated with human listeriosis. Listeriosis associated infection by L. ivanovii, and even by L. seeligeri, is extremely rare in humans. The universal occurrence of L. monocytogenes in food (42) and the risk of contracting foodborne listeriosis (47,48) have been thoroughly reviewed recently. This chapter describes the detection and enumeration of L. monocytogenes in foods and detection from food processing environment.
This standard methodology and alternative rapid methodologies are intended to be used for detection and isolation of L. monocytogenes from foods and environmental samples. Analytical sample size for foods is generally 25 g, and this can be from individual units or as part of a sample composite.
Alternatively, rapid test kits with their respective enrichment media approved as AOAC Official Methods of Analysis (OMA) may be conditionally used to screen for the presence of Listeria contaminants. Putative Listeria isolates on selective agars from standard or screen positive enrichments are purified on non-selective agars and confirmed by conventional identification tests or by a battery of such tests in kit form. Isolates may be rapidly confirmed as L. monocytogenes (or not) by using specific test kits or PCR procedures. Subtyping of L. monocytogenes isolates is generally expected, which includes serological typing and whole genome sequencing. Optional pathogenicity testing of L. monocytogenes isolates is described in Section H.
Enumeration of L. monocytogenes in positive food samples is performed on reserve sample by colony count on L. monocytogenes differential selective agars in conjunction with MPN enumeration using selective enrichment in buffered Listeria enrichment broth with subsequent plating on L. monocytogenes differential selective agars as described below.

更多内容请查看附件。