title: Molecular Epidemiology of Invasive Listeriosis due to Listeria monocytogenes in a Spanish Hospital over a Nine-Year Study Period, 2006-2014.
abstract: 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.
authors.affiliation: Instituto Tecnológico Agrario de Castilla y León, Valladolid, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Ariza-Miguel
authors.affiliation: Department of Clinical Microbiology, Complejo Asistencial Universitario de León, León, Spain ; Institute of Biomedicine (IBIOMED), University of León, León, Spain.
authors.forename: María Isabel
authors.initials: MI
authors.lastname: Fernández-Natal
authors.affiliation: Public Health, School of Physiotherapy ONCE, Madrid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Soriano
authors.affiliation: Instituto Tecnológico Agrario de Castilla y León, Valladolid, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Hernández
authors.affiliation: Institute of Milk Hygiene, Milk Technology and Food Science, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria.
authors.forename: Beatrix
authors.initials: B
authors.lastname: Stessl
authors.affiliation: Instituto Tecnológico Agrario de Castilla y León, Valladolid, Spain ; Microbiology Section, Department of Biotechnology and Food Science, Faculty of Sciences, University of Burgos, Burgos, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Rodríguez-Lázaro
mesh_terms: D015373:Bacterial Typing Techniques; D005516:Food Microbiology; D014644:Genetic Variation; D005838:Genotype; D006367:HeLa Cells; D006801:Humans; D008089:Listeria monocytogenes / Q000302:isolation & purification / Q000472:pathogenicity*; D008088:Listeriosis / Q000453:epidemiology* / Q000235:genetics / Q000382:microbiology; D017720:Molecular Epidemiology; D013030:Spain