Features

Microgen Listeria Latex

A latex agglutination presumptive test for the presence of Listeria spp in enrichment broths or confirm colonies on agar plate media. Microgen Listeria latex may be used in conjunction with biochemical tests (Microgen Listeria-ID) for further species identification.

Benefits
Results in 2 minutes
Cost effective
High sensitivity
High specificity
Accurate & reliable results
User friendly procedure

Detects the Listeria genus, including these species:

Listeria monocytogenes
Listeria innocua
Listeria welshimeri
Listeria ivanovii
Listeria seeligeri
Listeria grayi

Included in the kit:

• 2.5mls Test latex
• 0.5ml Positive control
• 5mls Isotonic Saline
• disposable reaction cards
• disposable mixing sticks

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 autoagglutination
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
   

Method from 48 hour enrichment broths

1.place 50µl of enrichment broth on to 2 wells of the reaction card

2.add 50µl test latex to one of the wells and 50µl control latex to the other, mix using a mixing stick

3.rock the slide for up to 2 minutes and examine for agglutination

Interpretation

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

Latex Agglutination Principle

• Polyvalent antisera raised against the 4 Listeria flagella antigens is used to coat latex particles.
• When mixed with a suspension of Listeria containing these antigens, the latex particles rapidly agglutinate forming visible clumps

Latex technology:

• Producer strains carrying specific antigens are cultured at optimal temperature for flagella production
• isolates sub cultured on to Jameson plates to select most motile organisms
• strains cultivated in broth
• Supernatant discarded and cell deposit treated to harvest flagella
• flagella immunogen used to generate antisera
• antisera titres checked and blended
• blended antisera purified and then coated on latex particles

Listeria spp possess 4 major flagellar antigen types designated A, B, C and E. All Listeria spp possess one or more of A, B, or C but L. grayi only possess E. Antiserum used to coat the latex particles must contain all 4 flagella antigens in order to detect all 6 Listeria spp.

Literature

Listeria Latex Brochure (265.89 kB)

TN12-15 (146.93 kB)

Specs