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The catalase test is
important in distinguishing streptococci (catalase-negative) from
staphylococci, which are vigorous catalase-producers. The test is performed
by adding 3% hydrogen peroxide to a colony on an agar plate or slant.
Catalase-positive cultures produce O2 and bubble at once.
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In terms of clinical
relevance, the staphylococci are conveniently divided into two groups: those
which produce a positive coagulase test within 24 hours (coagulase-positive
staphylococci, commonly identified and reported as Staphylococcus aureus) and
those which do not (coagulase-negative staphylococci, commonly identified and
reported as coagulase-negative Staphylococcus sp., or CNS). Nearly all
strains of Staph produce the enzyme coagulase. However, there is no
overwhelming evidence that it is a virulence factor, although it is
reasonable to speculate that the bacteria could protect themselves from
phagocytic and immune defenses by causing localized clotting.
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Clumping factor results when
strains express a fibrin type of binding protein that promotes attachment to
blood clots and traumatized tissue.
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Sample(s) to be collected
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Food poisoning samples ,
Stool and/or vomiteous
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Suspected foods, Any skin
lesions of suspected food handlers
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Pneumonia sample: Sputum
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