Carlin Catharine R, Roof Sherry, Wiedmann Martin
Department of Food Science, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York 14853, USA.
J Food Prot. 2022 Mar 1;85(3):494-510. doi: 10.4315/JFP-21-293.
Reference methods developed for detection of Listeria monocytogenes are commonly used for detection of Listeria at the genus level. Improved method performance data are needed because this genus has expanded from 6 to 26 species and now includes several Listeria sensu lato species, which can have phenotypes distinct from those of Listeria sensu stricto. We evaluated growth of 19 Listeria species, including 12 recently described Listeria sensu lato species, using the media specified by (i) the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual, (ii) the U.S. Department of Agriculture (USDA) Microbiology Laboratory Guidebook, and (iii) the International Organization for Standardization (ISO). The FDA broth enrichment procedure allowed all species to grow to detectable levels (≥4 log CFU/mL), yielded the highest mean growth (7.58 log CFU/mL), and was the only procedure with which no Listeria sensu lato species yielded significantly higher growth than did a comparison Listeria sensu stricto species. With the USDA and ISO broth enrichment procedures, several Listeria sensu lato species yielded significantly higher growth than did either Listeria seeligeri or Listeria ivanovii, suggesting that these two Listeria sensu stricto species could be outgrown by Listeria sensu lato species. On selective and differential agar media, L. seeligeri, L. ivanovii, and Listeria grayi produced colonies with atypical morphology and/or growth of these species was inhibited (which may lead to incorrect classification of a sample as negative), whereas several newly described Listeria sensu lato species grew to high levels and produced colonies with typical morphology. Overall, our study results indicate that the ability to detect various Listeria species can be impacted by the specific broth and selective and differential agar used. Our data can help guide selection of appropriate media and detection methods for environmental Listeria monitoring programs and methods that are most likely to detect the targeted Listeria groups (e.g., Listeria sensu stricto, which appear to be the most appropriate index organisms for the pathogen L. monocytogenes).
为检测单核细胞增生李斯特菌而开发的参考方法通常用于李斯特菌属水平的检测。由于该属已从6个物种扩展到26个物种，现在包括几个广义李斯特菌物种，其表型可能与狭义李斯特菌不同，因此需要改进方法性能数据。我们使用以下标准指定的培养基评估了19种李斯特菌的生长情况，其中包括12种最近描述的广义李斯特菌：（i）美国食品药品监督管理局（FDA）《细菌学分析手册》；（ii）美国农业部（USDA）《微生物学实验室指南》；（iii）国际标准化组织（ISO）。FDA肉汤增菌程序能使所有物种生长到可检测水平（≥4 log CFU/mL），平均生长量最高（7.58 log CFU/mL），并且是唯一一种没有广义李斯特菌物种比对照狭义李斯特菌物种生长显著更高的程序。对于USDA和ISO肉汤增菌程序，几种广义李斯特菌物种的生长显著高于西尔李斯特菌或伊万诺夫李斯特菌，这表明狭义李斯特菌的这两个物种可能会被广义李斯特菌物种超越。在选择性和鉴别性琼脂培养基上，西尔李斯特菌、伊万诺夫李斯特菌和格氏李斯特菌产生的菌落形态不典型，和/或这些物种的生长受到抑制（这可能导致将样本错误分类为阴性），而几种新描述的广义李斯特菌物种生长到较高水平并产生典型形态的菌落。总体而言，我们的研究结果表明，检测各种李斯特菌物种的能力可能会受到所用特定肉汤以及选择性和鉴别性琼脂的影响。我们的数据有助于指导为环境李斯特菌监测计划选择合适的培养基和检测方法，以及最有可能检测到目标李斯特菌群（例如狭义李斯特菌，似乎是单核细胞增生李斯特菌病原体最合适的指示生物）的方法。
