Salmonella

Taxonomy

According to recent work of Taxonomy, in particular by hybridization of DNA, the kind Salmonella comprises three S, the principal one (regarded a long time as only), Salmonella enterica includes/understands six S - of which most frequent is Salmonella enterica enterica - they-even divided into many Sérovar S (Enteritidis, Derby, Hadar, Infantis, Paratyphi, Typhi, Typhimurium, Virchow…).

The S of Salmonella are thus the following ones:

Salmonella bongori ;
Salmonella enterica ;
Salmonella enterica arizonae ;
Salmonella enterica diarizonae ;
Salmonella enterica enterica ;
Salmonella enterica houtenae ;
Salmonella enterica indica ;
Salmonella enterica salamae ;
Salmonella subterranea (since 2004).

In 2000, the National Reference Center of the Salmonella and Shigella (CNRS) of the Institute Pasteur, with Paris had referred 883 stocks of Salmonella of human origin. The Sérovar S Enteritidis and Typhimurium accounted for 36% and 29% respectively of them. One knows today more than 2000 stocks of salmonellas.

Biochemical characters

They are enterobacteries bacilli with negative Gram S, mobiles (Ciliature péritriche, optional aéro-anaerobes, Oxydase -, Nitrate réductase +, fermentative of glucose, lactose - H₂S +, Uréase -, Tryptophane désaminase +, using the way of the mixed acids, indol, not having the béta-galactosidase), with strong contagiousness, persons in charge of Gastro-entérite S, Toxi-infection S food and of the fevers typhoid and paratyphoid ( S. Typhi and S. Paratyphi).

Infectious amount

There is no standard infectious amount, that Ci depending:

of the pathogenicity of the stock (or Sérovar) considered
of factors of sensitivity of the host
of the microbial concentration (amount in contact or introduced).

Antigenic characters

Like all the Enterobacteriaceae , the Salmonella have somatic antigens O (located in the Paroi). There are 67, one distinguishes the antigen O major characterizing a group from Salmonella and the antigen O minor which is additional. The délétion by change of the antigen O involves a partial or total loss pathogenic Pouvoir.

The Salmonella also have flagellar antigens H. They are present in two different forms (phase). Either in the two forms simultaneously (diphasic) or in the form of only one phase (monophasic). These two phases are coded by two Gène S different but very close, they must come from the duplication of the same ancestral gene.

Lastly, Salmonella ser. Typhi, S. ser. Paratyphi C and S. ser. Dublin have the antigen capsulaire of polyosidic nature VI which can (more or less) mask the somatic antigen O. This last is uncovered by destruction of antigen VI (heating with 100 °C during 10 min).

Habitat

The salmonellas can survive several weeks in dry medium and several months in the Eau. They are thus found frequently in the polluted aquatic environments, the contamination by the Excrément S of carrying animals being very important. The Vertebrate S watery, in particular the Bird X (Anatidés) and the Reptile S (Chéloniens) are important vectors of salmonellas. The Poultry S, the Bovine S and the Ovine S being frequently contaminant animals, the salmonellas can be found in the Aliment S, in particular the Viande S and the believed egg S.

See too

Salmonellose

External bonds

Nomenclature of the salmonellas
Salmonella Page of [[Qualitionnaire]] the

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