BackgroundInvasive listeriosis is a rare, life-threatening foodborne disease. Lombardy, an Italian region accounting for 16% of the total population, reported 55% of all listeriosis cases in the years 2006-2010. The aim of our study was to provide a snapshot of listeriosis epidemiology in this region after the implementation of a voluntary laboratory-based surveillance system.MethodsWe characterized by serotyping, pulsed-field gel electrophoresis, multilocus sequence typing and detection of epidemic clone markers, 134 isolates from 132 listeriosis cases, including 15 pregnancy-related cases, occurring in the years 2006-2010 in Lombardy. Demographic and clinical characteristics of cases have also been described.ResultsThe mean age of non pregnancy-associated cases was 64.7 years, with 55.9% of cases being older than 65 years. Cases having no underlying medical conditions accounted for 11.6%. The all-cause fatality rate of 83 cases with a known survival outcome was 25.3%.Serotypes 1/2a and 4b comprised 52.2% and 38.8% of isolates, respectively. Seventy-three AscI pulsotypes and 25 sequence types assigned to 23 clonal complexes were recognized. Moreover, 53 (39.5%) isolates tested positive for the epidemic clone markers. Twelve molecular subtype clusters including at least three isolates were detected, with cluster 11 (1/2a/ST38) including 31 isolates identified during the entire study period. No outbreaks were notified to public health authorities during this period.ConclusionsThe findings of our study proved that epidemiology of listeriosis in Lombardy is characterized by a high prevalence of major clones and the increasing role of serotype 1/2a. Molecular subtyping is an essential tool in the epidemiology and surveillance of listeriosis. Rapid molecular cluster detection could alert about putative outbreaks, thus increasing the chance of detecting and inactivating routes of transmission.

Abstract.Background. In developed countries invasive listeriosis is an infection of great concern to public health to due its clinical severity and high fatality rate, despite its low incidence. In Europe, statistically significant increasing trends in listeriosis notification rates from 2005 to 2009 were noted in Austria, Denmark, Hungary, Italy, Spain and Sweden. Materials and methods. The standardized techniques based on phenotype to typing Listeria monocytogenes is the serotyping. In Europe, as elsewhere in the world, about 95% of L. monocytogenes strains isolated from clinical and food samples belongs to serovars 1/2a, 1/2b, 1/2c and 4b. Results. The target of this work is to draw attention to this important and atypical foodborne disease, reporting epidemiological data and serotypes distribution of 251 human L. monocytogenes isolates reported during 2000-2010 to Veterinary Public Health and Food Safety Department of Istituto Superiore di Sanità, focusing on epidemiological trend of invasive listeriosis in Lombardia, a North Italian Region. The serotypes most frequently identified are 1/2a, 4b, 1/2b (in total 92%), but the detection of uncommon serotypes is not missing (1/2c, 3a, 3b, 4d). Conclusions. In Italy the surveillance laboratory network, as well as the foodborne disease network (ENTER-NET), has revealed in the last 11 years an increase trend of listeriosis cases reported likewise with results of Notificable National Infectious Disease surveillance System. This is probably due to a real increase of listeriosis, even if there is a greater sensitivity of the network in some regions.Key words: Listeria monocytogenes, serotypes, surveillance. (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010). Introduzione. Nei Paesi industrializzati, nonostante la sua bassa incidenza la listeriosi invasiva è un'infezione alimentare di grande impatto per la salute pubblica, a causa della gravità delle sue manifestazioni cliniche e dell'alto tasso di letalità. In Europa, fra il 2005 e il 2009, sono stati notati incrementi, statisticamente significativi, delle notifiche di listeriosi in Austria, Danimarca, Ungheria, Italia, Spagna e Svezia. Materiali e metodi. Dal punto di vista fenotipico la tipizzazione sierologica rappresenta la tecnica più tradizionale per classificare gli stipiti di Listeria monocytogenes. In Europa come nel resto del mondo, il 95% circa dei ceppi di L. monocytogenes isolati da campioni clinici e alimentari appartengono ai sierotipi 1/2a, 1/2b, 1/2c e 4b. Risultati. L'obiettivo di questo studio è quello di attirare l'attenzione su questa grave e atipica malattia alimentare, riportando i dati epidemiologici e la distribuzione dei sierotipi, relativamente a 251 stipiti raccolti nel periodo 2000-2010, dal Dipartimento di Sanità Pubblica Veterinaria e Sicurezza Alimentare dell'Istituto Superiore di Sanità, focalizzando l'attenzione sui dati provenienti dalla Regione Lombardia. I sierotipi più frequentemente identificati sono 1/2a, 4b, 1/2b (per un complessivo 92%) ma non è mancato il risc...

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