Department of Infectious Disease Epidemiology, Statens Serum Institut, Copenhagen, Denmark.
Department of Infectious Disease Epidemiology, Statens Serum Institut, Copenhagen, Denmark; Department of Microbiology and Infection Control, Statens Serum Institut, Copenhagen, Denmark.
Clin Microbiol Infect. 2016 Jul;22(7):620-4. doi: 10.1016/j.cmi.2016.04.017. Epub 2016 May 1.
Listeria monocytogenes may contaminate and persist in food production facilities and cause repeated, seemingly sporadic, illnesses over extended periods of time. We report on the investigation of two such concurrent outbreaks. We compared patient isolates and available isolates from foods and food production facilities by use of whole-genome sequencing and subsequent multilocus sequence type and single nucleotide polymorphism analysis. Outbreak cases shared outbreak strains, defined as Listeria monocytogenes isolates belonging to the same sequence type with fewer than five single nucleotide polymorphism differences. We performed routine food consumption interviews of L. monocytogenes patients and compared outbreak cases with sporadic cases. Two outbreaks were defined, each consisting of ten outbreak cases in the period 2013-15. Seven outbreak cases and a fetus in gestational week 38 died. Listeria monocytogenes isolates from cold smoked or gravad fish products or their two respective production environments were repeatedly found to belong to the outbreak strains. Outbreak cases more often than sporadic cases stated that they consumed the relevant fish products, odds ratio 10.7. Routine collection and typing of food isolates was key to solving the outbreaks. Furthermore, these outbreaks illustrate the value of whole-genome sequencing for outbreak definition and investigation. Whole-genome sequencing combined with epidemiological investigations provided the discriminatory power to recognize low-intensity, extended time-period outbreaks and link them to food products from two different contaminated production facilities with sufficient strength for food authorities to intervene on. Cold smoked and gravad fish constitute risk products and may be responsible for more listeriosis cases than previously recognized.
李斯特菌可能会污染并存在于食品生产设施中，并在较长时间内导致反复出现、看似散发的疾病。我们报告了两起此类并发疫情的调查情况。我们通过全基因组测序以及随后的多位点序列类型和单核苷酸多态性分析，比较了患者分离株和食品及食品生产设施中可用的分离株。疫情病例共享疫情菌株，定义为属于同一序列类型且单核苷酸多态性差异少于 5 个的李斯特菌分离株。我们对李斯特菌患者进行了常规的食物消费访谈，并将疫情病例与散发病例进行了比较。定义了两起疫情，每起疫情都包括 2013-15 年期间的 10 例疫情病例。7 例疫情病例和一名妊娠 38 周的胎儿死亡。反复发现冷熏或腌制鱼产品或其各自生产环境中的李斯特菌分离株属于疫情菌株。与散发病例相比，疫情病例更常表示他们食用了相关的鱼产品，比值比为 10.7。常规收集和分型食物分离株是解决疫情的关键。此外，这些疫情说明了全基因组测序在疫情定义和调查中的价值。全基因组测序结合流行病学调查提供了足够的区分力，可以识别低强度、长时间的疫情，并将其与来自两个不同污染生产设施的食品产品联系起来，以便食品当局进行干预。冷熏和腌制鱼构成了风险产品，可能导致比以前认识到的更多的李斯特菌病例。
