Diagnosis

DIAGNOSIS
  • Cultural characters in selective media.
  • In case of food poisoning identification of the enterotoxin is of diagnostic use.
  • CPS produces typical reaction in the Hotis test of milk samples.
  • These organisms produced green or greenish brown colonies with white centres after the milk samples are incubated for 16-20 hours.
  • DNA test and protein A tests are also employed.

Pathogenicity test

  • Coagulase test: When culture added to Rabbit plasma, fibrinogen is converted to fibrin by coagulase enzymes.
  • In this test, a suspension of staphylococci is mixed with rabbit plasma either on a slide or in a small tube.
  • The slide test detects the presence of a bound coagulase or clumping factor on the bacterial surface.
  • A positive reaction is indicated by clumping of bacteria within 1 to2 min.
  • The tube test detects the free coagulase or staphylocoagulase, which is secreted by bacteria into the plasma.
  • It is the definitive test for coagulase production and positive reaction is indicated by clot formation in the tube following incubation at 37ºC for 24 hrs. (Click here for visual)

Phage typing

  • Phage typing is carried out for epidemiological purposes, particularly for S. aureus strains of bovine mastitis.

Last modified: Monday, 4 June 2012, 4:16 AM