STAPHYLOCOCCUS
STAPHYLOCOCCUS
Gram-positive cocci in clusters resembling bunches of grapes.
Grow on non-enriched media.
Moderately-sized white or golden colonies.
Colonies of S. aureus and S. intermedius produce double haemolysis.
Facultative anaerobes, non-motile, catalase-positive.
Commensals on mucous membranes and skin.
Coagulase production correlates with pathogenicity.
Slide and tube coagulase tests.
Slide and tube coagulase tests.
In these tests, a suspension of staphylococci is mixed with rabbit plasma either on a slide or in a small tube. The fibrinogen in rabbit plasma is converted to fibrin by coagulase.
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 one to two minutes.
The tube test detects free coagulase or staphylocoagulase which secreted by the bacteria into the plasma. It is the definitive test for coagulase production and a positive reaction is indicated by clot formation in the tube following incubation at thirty-seven degrees Celsius for twenty-four hours.
Comparatively stable in the environment.
The coagulase-positive S. aureus subsp. aureus (referred to as S. aureus) and S. intermedius, and the coagulase-variable S. hyicus are important pathogens of domestic animals.
Cause pyogenic infections.