Ariza-Miguel Jaime, Fernández-Natal María Isabel, Soriano Francisco, Hernández Marta, Stessl Beatrix, Rodríguez-Lázaro David
Instituto Tecnológico Agrario de Castilla y León, Valladolid, Spain.
Department of Clinical Microbiology, Complejo Asistencial Universitario de León, León, Spain ; Institute of Biomedicine (IBIOMED), University of León, León, Spain.
Biomed Res Int. 2015;2015:191409. doi: 10.1155/2015/191409. Epub 2015 Oct 11.
We investigated the pathogenicity, invasiveness, and genetic relatedness of 17 clinical Listeria monocytogenes stains isolated over a period of nine years (2006-2014). All isolates were phenotypically characterised and growth patterns were determined. The antimicrobial susceptibility of L. monocytogenes isolates was determined in E-tests. Invasion assays were performed with epithelial HeLa cells. Finally, L. monocytogenes isolates were subtyped by PFGE and MLST. All isolates had similar phenotypic characteristics (β-haemolysis and lecithinase activity), and three types of growth curve were observed. Bacterial recovery rates after invasion assays ranged from 0.09% to 7.26% (1.62 ± 0.46). MLST identified 11 sequence types (STs), and 14 PFGE profiles were obtained, indicating a high degree of genetic diversity. Genetic studies unequivocally revealed the occurrence of one outbreak of listeriosis in humans that had not previously been reported. This outbreak occurred in October 2009 and affected three patients from neighbouring towns. In conclusion, the molecular epidemiological analysis clearly revealed a cluster (three human cases, all ST1) of not previously reported listeriosis cases in northwestern Spain. Our findings indicate that molecular subtyping, in combination with epidemiological case analysis, is essential and should be implemented in routine diagnosis, to improve the tracing of the sources of outbreaks.
我们调查了在9年时间（2006 - 2014年）内分离出的17株临床单核细胞增生李斯特菌菌株的致病性、侵袭性和遗传相关性。对所有分离株进行了表型特征鉴定并确定了生长模式。采用E试验测定单核细胞增生李斯特菌分离株的抗菌药敏性。用上皮细胞HeLa进行侵袭试验。最后，通过脉冲场凝胶电泳（PFGE）和多位点序列分型（MLST）对单核细胞增生李斯特菌分离株进行亚型分型。所有分离株具有相似的表型特征（β溶血和卵磷脂酶活性），并观察到三种类型的生长曲线。侵袭试验后的细菌回收率在0.09%至7.26%之间（1.62±0.46）。MLST鉴定出11种序列类型（STs），并获得了14种PFGE图谱，表明遗传多样性程度较高。遗传学研究明确揭示了此前未报告的一起人类李斯特菌病暴发事件。该暴发发生在2009年10月，影响了来自邻近城镇的三名患者。总之，分子流行病学分析清楚地揭示了西班牙西北部一个此前未报告的李斯特菌病病例聚集群（三例人类病例，均为ST1型）。我们的研究结果表明，分子分型与流行病学病例分析相结合至关重要，应在常规诊断中实施，以改进对暴发源头的追踪。
