Liu Dongxin, Wang Yan, Wang Yi, Zhang Lu, Luo Lijuan, Liu Kai, Ye Changyun
State Key Laboratory of Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Chinese Center for Disease Control and Prevention, Changping, Changbai Road 155, Beijing 102206, People's Republic of China.
J Food Prot. 2017 Oct;80(10):1768-1776. doi: 10.4315/0362-028X.JFP-16-529.
Listeriosis, the disease caused by pathogenic Listeria species, can present severe symptoms in susceptible people. The goal of this study was to develop a novel enrichment broth, Listeria allose enrichment broth (LAEB), to improve isolation of Listeria monocytogenes and Listeria ivanovii from samples through incorporating a specific carbohydrate and reducing inhibitor concentrations. Other coexisting bacteria, particularly Listeria innocua, can interfere with the isolation of pathogenic Listeria in such ways as overgrowth of L. innocua and the generation of inhibitory metabolites. The incorporation of allose into the novel LAEB was effective for slowing the growth of L. innocua and other nontarget microorganisms. We determined that 35°C and pH 7.0 under aerobic conditions are optimal for Listeria growth in this medium. The novelty of the use of LAEB is the single enrichment procedure at 35°C for 24 h, obviating the need for a secondary enrichment medium. In 50 simulated samples, the sensitivity of the LAEB method (86%) was higher than that of the International Organization for Standardization (EN ISO) method (70%). In 142 naturally contaminated samples tested, the isolation rate for pathogenic Listeria with the LAEB method was 26.0% (37 of 142 samples), which was significantly higher than the 17.6% (25 of 142 samples) for the EN ISO method. Higher isolation rates and a quicker and easier protocol make the novel LAEB method an appropriate alternative for the isolation of pathogenic Listeria.
李斯特菌病是由致病性李斯特菌属引起的疾病，在易感人群中可表现出严重症状。本研究的目的是开发一种新型增菌肉汤——李斯特菌阿洛糖增菌肉汤（LAEB），通过加入特定碳水化合物并降低抑制剂浓度，来提高从样品中分离单核细胞增生李斯特菌和伊氏李斯特菌的能力。其他共存细菌，特别是无害李斯特菌，可能会以无害李斯特菌过度生长和产生抑制性代谢产物等方式干扰致病性李斯特菌的分离。在新型LAEB中加入阿洛糖可有效减缓无害李斯特菌和其他非目标微生物的生长。我们确定，在有氧条件下35°C和pH 7.0是该培养基中李斯特菌生长的最佳条件。LAEB使用的新颖之处在于在35°C下进行单一增菌程序24小时，无需二次增菌培养基。在50个模拟样品中，LAEB方法的灵敏度（86%）高于国际标准化组织（EN ISO）方法（70%）。在142个自然污染样品的测试中，LAEB方法对致病性李斯特菌的分离率为26.0%（142个样品中的37个），显著高于EN ISO方法的17.6%（142个样品中的25个）。更高的分离率以及更快、更简便的方案使新型LAEB方法成为分离致病性李斯特菌的合适替代方法。
