Slidex Staph Plus (Rapid Coagulase Test)

Slidex Staph Plus is not for use directly with clinical or other specimens. The microorganisms to be identified must first be isolated as separate colonies by streaking the specimen on appropriate culture media according to standard microbiological techniques.

Principle:

The SLIDEX staph Plus reagent comprises blue latex particles sensitized with human fibrinogen and monoclonal antibodies. It therefore enables the simultaneous detection of:

• Clumping factor 
• Protein A using the Fc fragment of mouse IgG 
• A group-specific antigen bound to S. aureus-specific preripheral structures. 

A positive test for S. aureus will be observed by a visible agglutination reaction without the use  of a magnifying glassed lens.

Procedure:

• Allow reagents to come to room temperature (18-25C) before use. 
• Re-suspend the latex reagents. Remove bubbles remaining in the dropper. 
• On a disposable card, choose 2 adjacent reaction circles and label with reference number. 
• To one circle add 1 drop of R1 (anti-Staphylococcus aureus latex). To the second circle add 1 drop of R2 (negative control latex). Hold the bottles in a vertical position dispensing the reagents. 
• Using two different disposable stirring sticks or plastic loops, add suspect colonies to each of the two test circles: 1-2 medium-sized colonies from a non-selective medium, e.g., Columbia agar + blood, or 3-6 small colonies from a selective medium, e.g., Mannitol salt agar. 
• Mix the test colony well in the drop of reagent for 10 full seconds using the disposable stirrer or loop. Spread the latex over the entire area of the circle. 
• Slowly rock the card for 20 seconds while observing for agglutination. Read the reaction under normal lighting conditions and without the aid of magnifying lens. 

Interpretation:

• A positive result is indicated by visible agglutination of the latex particles in reagent R1 within 30 seconds (time taken to mix the colonies and reagent, then rotate the card) and absence of agglutination in reagent R2. 
• A negative result is indicated by the absence of agglutination with reagents R1 and R2. 
• The test is uninterruptible if the reagent R2 shows agglutination. 

Note: If the agglutination is very weak with reagent R1 or if the reaction is uninterruptible, identification of the colonies should be performed with the tube coagulase test or a biochemical range of tests. A filament-producing reaction observed with reagent R1 only should not be considered positive.