Salmonella enterica subsp. enterica - Molecular antigenic typing; Molecular diagnosis (PCR); Antibodies to antigens O and H; Molecular comparison of strains.
Salmonella spp., Is a heterogeneous group of bacteria of the family Enterobacteriaceae. Until recently, many species had been considered, because each serotype was considered a different species. Currently, only two species, Salmonella enterica, with six subspecies (enterica [I], salamae [II], arizonae [IIIa], diarizonae [IIIb], houtenae [IV], and indicates [V]) are supported, and Salmonella bongori with a unique subspecies. Salmonella enterica subspecies are divided into serogroups 50, according to differences in their antigenic lipopolysaccharide (O antigens), of which 46 are currently known variants. Differences will flagellar antigens phase 1 and phase 2, of which 114 variants are known, differentiate Salmonella serotypes, each with an antigenic formula which is reflected in the scheme White, Kauffmann and Le Minor (or Kauffmann -White), that distinguish over 2,600 serotypes, of which 1,500 belong to Salmonella enterica subsp. enterica. Updating serotypes corresponds to the Reference Center of WHO at the Pasteur Institute in Paris. Most Salmonella serotypes isolated from human samples, or warm - blooded animals, belong to Salmonella enterica subsp. enterica (I) of the following serogroups: A, B, C1, C2, D, E1, E2, E3 and E4. To identify serogroups and serotypes, many specific for each of the serogroups sera and sera specific flagellar antigens for phase 1 and phase 2 are needed Typing of these antigens by agglutination procedures monoespecóficos sera is the method of reference (gold standard), but to realize more than 250 sera anti-O and anti-H are required. However, this method is unable to tipar mucoid or rough strains.
Salmonella classification beyond the level of subspecies, sometimes it is important for clinical and epidemiological research, to find the source of infection, being some of the serovars associated with specific hosts or specific geographic regions. Furthermore, also they relate to the severity of the disease, and the antimicrobial resistance.
Salmonella enterica subsp. enterica, is the group most clinically relevant, by its usual association with people and warm - blooded animals.
We used several methods to complement the Serology, for epidemiological tracing of isolates: the electrofoirresis pulsed field (Pulse-field gel electrophorsis), enzyme electrophoresis (multilocus enzyme electrophoresis) analysis of repeated sequences ( Variable-number-tandem-repeat analysis), the multilocus sequence typing (multilocus sequence typing), sequencing repeated palindromic sequences (palindromic extragenic repetitive sequence based PCR), ribotyping (ribotyping). These methods allow predict limited number of serovars, but its use has been limited by technical requirements, and can also lead to misidentifications of serovars.
The genes responsible for expression of the O antigens as transferases monosaccharide (sugar transferases), or genes for the synthesis of O antigens (O-antigen flippase - wzx -, or Polymerase - wzy - located in a regulon call set rfp. comparing wzx genes and wzy has been considered useful for designing específos primers serogroups. the rensponsables synthesis genes of flagellar flagellin fliC (phase 1 flagellin) and fljB (phase 2 flagellin), ends have terminal conserved and highly variable in the central region encoding the antigen.
Tests in IVAMI:
• anti- Salmonella subsp. enterica serovars Typhi, Paratyphi A, Paratyphi B, Paratyphi and C (O and H antigens of each species) by direct agglutination.
• molecular comparison of strains.
• Determination of serogroup O.
• Determination of full serotype (serogroup O, flagellar phase 1 and phase 2 flagellar).
• cultic and / or PCR: clinical sample of blood, feces, ...
• Determination of antibodies: serum.
• Determination of serogroup and / or serotype; Comparison of strains: isolated cultivation of Salmonella enterica subsp. enterica samples obtained from any source.
Preservation and shipment of sample:
Refrigerated (preferred) for less than 2 days.
Identification of serogroup and / or serotype full: maximum 5 days.
Cost of the test: