Hellenic Agricultural Organisation-DEMETER, Veterinary Research Institute of Thessaloniki, Thermi, Greece.
Department of Epidemiology and Public Health, Sciensano, Brussels, Belgium.
J Appl Microbiol. 2019 May;126(5):1373-1382. doi: 10.1111/jam.14244. Epub 2019 Mar 25.
The aim of this study was to evaluate the genetic diversity and resistance phenotypes of Listeria monocytogenes strains isolated from clinical encephalitis cases, and compare this population to isolates derived from tank milk of healthy animals.
A total of 57 L. monocytogenes strains isolated from ruminant's listeriosis cases (n = 31) and from tank milk of healthy ruminants (n = 26) were characterized by species PCR, molecular serotyping, PCR detection of virulence genes, pulsed-field gel electrophoresis and antimicrobial susceptibility testing. All strains possessed inlA, inlC, inlJ, plcA, actA, hlyA and iap virulence-associated genes while serotyping analysis revealed that they were mainly assigned into IVb group. Genotyping revealed 50 pulsotypes among the 57 strains assigned into seven clusters while indistinguishable pulsotypes between clinical and milk strains were not identified. Resistance of L. monocytogenes isolates to 14-16 antimicrobial agents tested was observed and 23 antimicrobial resistance profiles (ARPs) were defined while no apparent predominant ARP type was observed among isolates.
Small ruminants are exposed to a broad range of antimicrobial-resistant as well as genetically diverse strains of L. monocytogenes carrying virulence-associated genes but not all of them associated with the disease. Pulsed-field gel electrophoresis analysis suggests that pulsotypes associated with encephalitis are found in farms only in association with listeriosis.
These findings are valuable in understanding the ecology of this important food-borne pathogen and creating awareness for the emerging antimicrobial resistance.
本研究旨在评估从临床脑炎病例中分离的李斯特菌的遗传多样性和耐药表型，并将该人群与来自健康动物罐奶的分离株进行比较。
从反刍动物李斯特菌病病例（n=31）和健康反刍动物罐奶（n=26）中分离出的共 57 株李斯特菌通过物种 PCR、分子血清分型、毒力基因 PCR 检测、脉冲场凝胶电泳和抗菌药物敏感性试验进行了特征描述。所有菌株均携带 inlA、inlC、inlJ、plcA、actA、hlyA 和 iap 等与毒力相关的基因，而血清分型分析表明它们主要归为 IVb 组。基因分型显示，57 株菌株中有 50 种脉冲型分为 7 个簇，而临床菌株和奶菌株之间未发现相同的脉冲型。57 株分离株对 14-16 种测试抗菌药物的耐药性进行了观察，并定义了 23 种抗菌药物耐药谱（ARPs），但未观察到分离株中存在明显的主要 ARP 类型。
小型反刍动物暴露于携带与毒力相关基因的广泛耐药和遗传多样性的李斯特菌中，但并非所有李斯特菌都与疾病有关。脉冲场凝胶电泳分析表明，与脑炎相关的脉冲型仅在李斯特菌病相关的农场中发现。
这些发现对于了解这种重要食源性病原体的生态学以及提高对抗菌药物耐药性的认识具有重要价值。
