Analysis of Multilocus Sequence Typing and Virulence Characterization of Listeria monocytogenes Isolates from Chinese Retail Ready-to-Eat Food.
Analysis of Multilocus Sequence Typing and Virulence Characterization of Listeria monocytogenes Isolates from Chinese Retail Ready-to-Eat Food.
复制标题
中国零售即食食品中单增李斯特菌的多位点序列分型和毒力特征分析
DOI：
10.3389/fmicb.2016.00168
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发表时间：
2016
影响因子：
5.2
通讯作者：
Guo W
中科院分区：
文献类型：
--
作者：
Wu S;Wu Q;Zhang J;Chen M;Guo W
从中国零售即食食品（RTE）中分离出80株单核细胞增生李斯特菌，并进行了血清分型和抗生素敏感性试验。本研究的目的是通过多位点序列分型（MLST）、毒力相关基因、流行克隆（ECs）和重要毒力因子inlA （inlA）的序列分析来表征这些单核增生乳杆菌的亚型和毒力潜力。MLST分析结果表明，这些单核增生乳杆菌分离株属于14种不同的序列类型（STs）。除了4个新的STs （ST804、ST805、ST806和ST807）外，本研究中观察到的所有其他STs都在不同程度上与人类李斯特菌病和暴发有关。选择6个毒力相关基因（inlA、inlB、inlC、inlJ、hly和llsX），用PCR方法检测它们的存在。所有菌株均携带inlA、inlB、inlC、inlJ和hly，而38.8%（31/80）的菌株携带李斯特菌溶素S基因（llsX）。采用多重PCR法检测单核增生乳杆菌流行克隆特异性标记的存在，鉴定出4b-4d-4e菌株的ECI为26.3%（21/80）。进一步的inlA测序研究表明，大多数菌株含有入侵宿主细胞所需的全长inlA，而三个突变导致PMSC在新的PMSCs的326位（GAA→TAA）过早停止密码子（PMSC）。MLST序列与inlA序列分析结果一致，但菌株间存在不同的毒力潜力。这些结果表明，从中国RTE食品中分离出的单核细胞增生乳杆菌可能具有毒性，能够引起人类疾病。此外，单核增生乳杆菌分离株的STs和毒力谱对该病原体的流行病学和公共卫生研究具有重要意义。
Eighty Listeria monocytogenes isolates were obtained from Chinese retail ready-to-eat (RTE) food and were previously characterized with serotyping and antibiotic susceptibility tests. The aim of this study was to characterize the subtype and virulence potential of these L. monocytogenes isolates by multilocus sequence typing (MLST), virulence-associate genes, epidemic clones (ECs), and sequence analysis of the important virulence factor: internalin A (inlA). The result of MLST revealed that these L. monocytogenes isolates belonged to 14 different sequence types (STs). With the exception of four new STs (ST804, ST805, ST806, and ST807), all other STs observed in this study have been associated with human listeriosis and outbreaks to varying extents. Six virulence-associate genes (inlA, inlB, inlC, inlJ, hly, and llsX) were selected and their presence was investigated using PCR. All strains carried inlA, inlB, inlC, inlJ, and hly, whereas 38.8% (31/80) of strains harbored the listeriolysin S genes (llsX). A multiplex PCR assay was used to evaluate the presence of markers specific to epidemic clones of L. monocytogenes and identified 26.3% (21/80) of ECI in the 4b-4d-4e strains. Further study of inlA sequencing revealed that most strains contained the full-length InlA required for host cell invasion, whereas three mutations lead to premature stop codons (PMSC) within a novel PMSCs at position 326 (GAA → TAA). MLST and inlA sequence analysis results were concordant, and different virulence potentials within isolates were observed. These findings suggest that L. monocytogenes isolates from RTE food in China could be virulent and be capable of causing human illness. Furthermore, the STs and virulence profiles of L. monocytogenes isolates have significant implications for epidemiological and public health studies of this pathogen.