title: Virulence gene profiling and pathogenicity characterization of non-typhoidal Salmonella accounted for invasive disease in humans.
abstract: Human infection with non-typhoidal Salmonella serovars (NTS) infrequently causes invasive systemic disease and bacteremia. To understand better the nature of invasive NTS (iNTS), we studied the gene content and the pathogenicity of bacteremic strains from twelve serovars (Typhimurium, Enteritidis, Choleraesuis, Dublin, Virchow, Newport, Bredeney, Heidelberg, Montevideo, Schwarzengrund, 9,12:l,v:- and Hadar). Comparative genomic hybridization using a Salmonella enterica microarray revealed a core of 3233 genes present in all of the iNTS strains, which include the Salmonella pathogenicity islands 1-5, 9, 13, 14; five fimbrial operons (bcf, csg, stb, sth, sti); three colonization factors (misL, bapA, sinH); and the invasion gene, pagN. In the iNTS variable genome, we identified 16 novel genomic islets; various NTS virulence factors; and six typhoid-associated virulence genes (tcfA, cdtB, hlyE, taiA, STY1413, STY1360), displaying a wider distribution among NTS than was previously known. Characterization of the bacteremic strains in C3H/HeN mice showed clear differences in disease manifestation. Previously unreported characterization of serovars Schwarzengrund, 9,12:l,v:-, Bredeney and Virchow in the mouse model showed low ability to elicit systemic disease, but a profound and elongated shedding of serovars Schwarzengrund and 9,12:l,v:- (as well as Enteritidis and Heidelberg) due to chronic infection of the mouse. Phenotypic comparison in macrophages and epithelial cell lines demonstrated a remarkable intra-serovar variation, but also showed that S. Typhimurium bacteremic strains tend to present lower intracellular growth than gastroenteritis isolates. Collectively, our data demonstrated a common core of virulence genes, which might be required for invasive salmonellosis, but also an impressive degree of genetic and phenotypic heterogeneity, highlighting that bacteremia is a complex phenotype, which cannot be attributed merely to an enhanced invasion or intracellular growth of a particular strain.
authors.affiliation: The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel.
authors.forename: Jotham
authors.initials: J
authors.lastname: Suez
authors.forename: Steffen
authors.initials: S
authors.lastname: Porwollik
authors.forename: Amir
authors.initials: A
authors.lastname: Dagan
authors.forename: Alex
authors.initials: A
authors.lastname: Marzel
authors.forename: Yosef Ilan
authors.initials: YI
authors.lastname: Schorr
authors.forename: Prerak T
authors.initials: PT
authors.lastname: Desai
authors.forename: Vered
authors.initials: V
authors.lastname: Agmon
authors.forename: Michael
authors.initials: M
authors.lastname: McClelland
authors.forename: Galia
authors.initials: G
authors.lastname: Rahav
authors.forename: Ohad
authors.initials: O
authors.lastname: Gal-Mor
mesh_terms: D000818:Animals; D058947:Bacterial Secretion Systems / Q000235:genetics; D055028:Comparative Genomic Hybridization; D004847:Epithelial Cells / Q000382:microbiology; D005260:Female; D015870:Gene Expression; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D006801:Humans; D008264:Macrophages / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D010802:Phylogeny; D012475:Salmonella / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity*; D012480:Salmonella Infections / Q000382:microbiology*; D014774:Virulence / Q000235:genetics*; D037521:Virulence Factors / Q000235:genetics
chemical_list: D058947:Bacterial Secretion Systems; D037521:Virulence Factors