Gram stain: The Gram stain, is a laboratory staining technique that distinguishes between two groups of bacteria that have differences in the structure of their cell walls. Standard bacterial taxonomy makes a distinction between Gram-negative bacteria, which stain red/pink and the Gram-positive bacteria, which stain blue/purple. Different antimicrobial agents are directed specifically at gram-positive bacteria and gram-negative bacteria.
      Gram + cocci clusters
Slide coagulase test: The slide Coagulase test detects bound coagulase (clumping factor). This type of coagulase is attached to the bacterial cell walls (surface). This test is usually performed on a glass slide.
Tube Coagulase test: The coagulase test is used to differentiate Staphylococcus aureus from coagulase-negative staphylococci. The test uses rabbit plasma that has been inoculated with a staphylococcal colony. The tube is then incubated at 37 degrees Celsius for 1-1/2 hours. If negative, then incubation is continual up to 24 hours. This test detects free coagulase (coagulase that is released by bacterial cells into culture).
        
Positive (i.e., the suspect colony is S. aureus). The serum will coagulate, resulting in a clot (sometimes the clot is so pronounced that the liquid will completely solidify).
         Negative, the plasma remains liquid. A negative result may be S. epidermidis.
                      Slide coagulase
Catalase test: The catalase test is used to differentiate some bacterial species. The test is done by placing a drop of hydrogen peroxide on a microscope slide. Using an applicator stick, a small portion of a colony is then added to a drop of hydrogen peroxide drop.
   Catalase positive
Tube Coagulase test: The coagulase test is used to differentiate Staphylococcus aureus from coagulase-negative staphylococci. The test uses rabbit plasma that has been inoculated with a staphylococcal colony. The tube is then incubated at 37 degrees Celsius for 1-1/2 hours. If negative, then incubation is continual up to 24 hours. This test detects free coagulase (coagulase that is released by bacterial cells into culture).
        
Positive (i.e., the suspect colony is S. aureus). The serum will coagulate, resulting in a clot (sometimes the clot is so pronounced that the liquid will completely solidify).
         Negative, the plasma remains liquid. A negative result may be S. epidermidis.

Negative Perform

tube coagulase test

 If tube coagulase positive:

Staphylococcus aureus

PYR positive

Staphylococcus lugdunensis

PYR test: the PYR test is a qualitative procedure for determining the ability of streptococci to enzymatically hydrolyze L-pyrrolidonyl- β-napthylamide (PYR). A positive PYR tests allows for the presumptive identification of group A streptococci (Streptococcus pyogenes) and group D Enterococci.

PYR negative

Perform tube coagulase test

Non-hemolytic (γ-hemolysis): If an organism does not induce any hemolysis on a blood agar plate, it is said to display gamma or no hemolysis. The agar under and around the colony is unchanged.

Positive but clumpy

Colony more white; non-hemolytic on Day 1

Alpha hemolysis (α-hemolysis): Alpha hemolysis is the incomplete lysis of the red blood cells around and under the colonies on a blood agar plate. This area appears dark and greenish. Streptococcus pneumoniae and a group of streptococci (Streptococcus viridans or viridans streptococci) found in oral flora display alpha hemolysis.
Beta hemolysis (β-hemolysis): Beta hemolysis is the complete lysis of the red blood cells around and under the colonies on a blood agar plate. This area appears transparent. Streptococcus pyogenes displays beta hemolysis and is often called Group A beta-hemolytic strep (GABHS).

Positive

Typical hemolytic colony

Staphylococcus aureus

Staphylococci

  Major pathogen: Staphylococcus aureus

  Others: S. lugdunensis in abscesses and serious wounds; Coagulase-negative staph in multiple blood cultures

@ Ellen Jo Baron 2007

PYR test: the PYR test is a qualitative procedure for determining the ability of streptococci to enzymatically hydrolyze L-pyrrolidonyl- β-napthylamide (PYR). A positive PYR tests allows for the presumptive identification of group A streptococci (Streptococcus pyogenes) and group D Enterococci.

If PYR and coagulase negative:

Coagulase negative staphylococci