Step 1: Understanding the Concept: The differentiation of staphylococcal species is a fundamental procedure in clinical microbiology to identify pathogenic strains.
Step 2: Key Formula or Approach: The approach involves identifying the presence of specific enzymes (like coagulase) that are unique to certain pathogenic strains of bacteria.
Step 3: Detailed Explanation: Staphylococcus aureus produces the enzyme coagulase, which converts fibrinogen to fibrin, causing plasma to clot.
This biochemical reaction forms the basis of the Coagulase Test.
Other clinically significant Staphylococcus species, such as S. epidermidis and S. saprophyticus, do not produce this enzyme and are therefore classified as coagulase-negative staphylococci (CoNS).
The Catalase test is used to differentiate Staphylococcus (which are positive) from Streptococcus (which are negative).
Step 4: Final Answer: The Coagulase test is the definitive biochemical test used to distinguish S. aureus from other staphylococci.