INTRODUCTION
Much of the information found in this chapter is adapted from the literature of the manufacturers of the kit systems described. Where possible, manufacturers details will be listed.
The brand used in practicals will vary from time to time, and so details of exact requirements/procedures may not be the same. Always check the instructions supplied with the kit.
STAPHAUREX PLUS
Coagulase Latex Co-agglutination video
Supplier: Oxoid Australia
Staphaurex Plus is used to differentiate coagulase positive Staphylococci from coagulase negative strains and replaces the conventional coagulase test described in the Biochemical testing section. The test utilises a reagent consisting of latex beads coated with fibrinogen and antibody to protein A (which is characteristic of S. aureus). When a coagulase positive S. aureus strain is mixed with the reagent, it causes the latex beads to agglutinate due to clotting of fibrin by clumping factor and cross linking via antibody and protein A. Staphaurex Plus also contains antibodies to certain strains of Methicillin resistant S. aureus (MRSA) which tend to be negative in conventional coagulase tests. Thus these latex agglutinations should identify all strains of S. aureus in a simple slide agglutination test. Some strains of S. saprophyticus may cause non-specific agglutination of latex particles and so a control latex suspension which is not specific for Staphylococci is included in the kit.
PROCEDURE
- Mix the bottles of test and control reagent well.
- Pick up several colonies of test bacteria and smear onto a well on the card supplied.
- Place a drop of each reagent onto the bacteria and mix with a clean toothpick.
- Rock the card gently and observe for visible clumping or agglutination of the latex particles. If positive, this should occur almost immediately as the colonies are mixed into the reagent. Do not observe for longer than 30 seconds.
- Repeat for the control reagent. If the control well agglutinates, a conventional tube coagulase must be carried out.
- Dispose of test card into the infectious waste containers.
RESULTS
POSITIVE Agglutination in test but not control
NEGATIVE No agglutination in either well
CONTROL ORGANISMS
POSITIVE S. aureus
NEGATIVE S. epidermidis