Department of Veterinary Public Health and Food Science, Institute of Milk Hygiene, Milk Technology, and Food Science, University of Veterinary Medicine, Vienna, Austria.
J Appl Microbiol. 2009 Feb;106(2):651-9. doi: 10.1111/j.1365-2672.2008.04039.x.
The aim of the study was to test the performance of commercially available chromogenic plating media for detection and enumeration of the food-borne pathogen Listeria monocytogenes. A wide range of chromogenic media similar to Agar Listeria according to Ottaviani and Agosti (ALOA) were compared using PALCAM agar, according to van Netten et al.
Six chromogenic media similar to ALOA were challenged for inclusivity and exclusivity. Additionally, the ability of chromogenic agars to facilitate growth of stressed L. monocytogenes strains and mixed cultures with competitive non-Listeria strains was estimated. Finally, we tested the detection and enumeration of L. monocytogenes in artificially inoculated and naturally contaminated food samples. The results of this study indicated that chromogenic media are a good supplementation to PALCAM agar. A single application is not advisable, as the specificity of chromogenic agars is frequently insufficient (50.0-88.9%), particularly in food samples with a complex microflora.
The competitive flora of food samples is able to overgrow low numbers of L. monocytogenes, especially in half-Fraser enrichment. This might lead to the underestimation of L. monocytogenes positive samples.
Although many evaluation studies of chromogenic agar have been published recently, harmonized validation strategies are lacking. This survey provides a new concept for stepwise testing of plating media.
本研究旨在测试市售显色平板培养基在检测和计数食源性病原体单核细胞增生李斯特菌方面的性能。本研究使用 PALCAM 琼脂，根据 van Netten 等人的方法，对类似于 Ottaviani 和 Agosti（ALOA）琼脂的多种显色平板培养基进行了比较。
对 6 种类似于 ALOA 的显色平板培养基进行了包容性和排他性测试。此外，还评估了显色琼脂促进应激型单核细胞增生李斯特菌菌株和与非李斯特菌竞争菌株混合培养生长的能力。最后，我们测试了在人工接种和自然污染食品样品中检测和计数单核细胞增生李斯特菌的能力。本研究结果表明，显色培养基是 PALCAM 琼脂的良好补充。不建议单独使用，因为显色琼脂的特异性经常不足（50.0-88.9%），特别是在微生物群复杂的食品样品中。
食品样品的竞争菌群能够过度生长低数量的单核细胞增生李斯特菌，尤其是在半 Fraser 增菌中。这可能导致低估单核细胞增生李斯特菌阳性样品。
尽管最近已经发表了许多关于显色琼脂的评估研究，但缺乏协调的验证策略。本研究提供了一种用于平板培养基逐步测试的新概念。
