Microgen Salmonella Latex

A latex agglutination confirmation test for the presence of Salmonella spp on solid media from clinical and food samples. Detects motile and non motile strains. Reduces testing delays associated with conventional methods. The Salmonella latex agglutination kit offers a rapid alternative to the traditional identification methods and detects a large range of Salmonella species including. S.typhimurium, S.enteritidis, S.virchow, S.newport, S.infantis, S.anatum, and various others belonging to serogroups B, C1, C2, C3, D1 and E1.

Method from plates

1. place 1 drop of saline on to a well of the reaction card
2. remove a typical looking colony from the plate using a loop and emulsify in the drop of saline
3. rock the slide gently for 2mins to check for auto-agglutination
4. add 1 drop of test latex to the suspension, mix using a mixing stick
5. rock the slide for up to 2 minutes and examine for agglutination

Interpretation

• agglutination within 2 minutes is indicative of the presence of Salmonella spp in the sample
• absence of agglutination indicates that Salmonella spp are not present in the sample

Background

The genus Salmonella consists of >2000 serotypes. Can cause acute infectious enteritis frequently associated with food poisoning. Many Salmonella species infect domestic animals clinically or sub-clinically therefore many cases of Salmonella food poisoning originate from animal sources. In contrast S.typhiand S.paratyphionly infect humans and cause enteric fever. Salmonella are usually present in samples in low numbers therefore enrichment or selective media are used to promote their growth eg RV, SC, M- broth

Latex Agglutination Principle

• Polyvalent antisera raised against a variety of Salmonella flagella antigens is used to coat latex particles.
• When mixed with a suspension of Salmonella containing these antigens, the latex particles rapidly agglutinate forming visible clumps
• Microgen Salmonella Latex test detects the majority of common species including S. typhimuriumand S. enteritidis
• In addition, the non-motile S. gallinarumand S. pullorumare also detected as they retain the protein basal bodies which are the attachment points for flagella

Latex technology:

• Producer strains carrying specific antigens are cultured
• Jameson plates used to purify strain to single phase as strains can be present in 2 flagella phases
• strains cultivated to produce immunogen
• immunogen used to generate antisera
• antisera titres checked and blended
• blended antisera purified and then coated on latex particles