title: Salmonella enterica Serotype Napoli is the First Cause of Invasive Nontyphoidal Salmonellosis in Lombardy, Italy (2010-2014), and Belongs to Typhi Subclade.
abstract: Salmonella enterica serotype Napoli (S. Napoli) is currently emerging in Europe and particularly in Italy, where in 2014 it caused a large outbreak associated with elevated rates of bacteremia. However, no study has yet investigated its invasive ability and phylogenetic classification. Here, we show that between 2010 and 2014, S. Napoli was the first cause of invasive salmonellosis affecting 40 cases out of 687 (invasive index: 5.8%), which is significantly higher than the invasive index of all the other nontyphoidal serotypes (2.0%, p < 0.05). Genomic and phylogenetic analyses of an invasive isolate revealed that S. Napoli belongs to Typhi subclade in clade A, Paratyphi A being the most related serotype and carrying almost identical pattern of typhoid-associated genes. This work presents evidence of invasive capacity of S. Napoli and argues for reconsideration of its nontyphoidal category.
authors.affiliation: 1 Dipartimento di Scienze della Salute, Università degli Studi di Milano , Milan, Italy .
authors.forename: Pol
authors.initials: P
authors.lastname: Huedo
authors.affiliation: 1 Dipartimento di Scienze della Salute, Università degli Studi di Milano , Milan, Italy .
authors.forename: Maria
authors.initials: M
authors.lastname: Gori
authors.affiliation: 2 Dipartimento di Scienze Cliniche e di Comunità, Università degli Studi di Milano , Milan, Italy .
authors.forename: Anna
authors.initials: A
authors.lastname: Zolin
authors.affiliation: 1 Dipartimento di Scienze della Salute, Università degli Studi di Milano , Milan, Italy .
authors.forename: Ettore
authors.initials: E
authors.lastname: Amato
authors.affiliation: 1 Dipartimento di Scienze della Salute, Università degli Studi di Milano , Milan, Italy .
authors.forename: Giulia
authors.initials: G
authors.lastname: Ciceri
authors.affiliation: 2 Dipartimento di Scienze Cliniche e di Comunità, Università degli Studi di Milano , Milan, Italy .
authors.forename: Anna
authors.initials: A
authors.lastname: Bossi
authors.affiliation: 1 Dipartimento di Scienze della Salute, Università degli Studi di Milano , Milan, Italy .
authors.forename: Mirella
authors.initials: M
authors.lastname: Pontello
mesh_terms: D004269:DNA, Bacterial / Q000302:isolation & purification; D004196:Disease Outbreaks; D005798:Genes, Bacterial; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D010802:Phylogeny; D012478:Salmonella Food Poisoning / Q000175:diagnosis / Q000453:epidemiology*; D012480:Salmonella Infections / Q000175:diagnosis / Q000453:epidemiology*; D019779:Salmonella enterica / Q000235:genetics* / Q000302:isolation & purification*; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial
keywords: Salmonella Napoli; Salmonella Typhi; bacteremia; invasive salmonellosis; phylogeny