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 chains

Beta hemolytic Streptococci

Major pathogens: Streptococcus pyogenes (group A) & S. agalactiae (group B)

@ Ellen Jo Baron 2007

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 negative

S. pyogenes (group A)
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 positive
CAMP +
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.
CAMP: This is a test performed on sheep blood agar to identify Group B β-streptococci based on their formation of a substance (CAMP factor) that enlages the area of hemoysis formed by streptococcal β-hemolysin.
PYR negative
S. agalactiae (group B)
If none of the above: β-strep not A or B

 

  Group A positive
   Group B positive

 Tiny colonies <0.5 mm Caramel smell "S. milleri" group

 

 

 

                                                                                                                                                 

   Latex agglutination - Lancefield groups
   Latex agglutination - Lancefield groups
Latex agglutination - Lancefield groups: Most pathogenic streptococci possess specific carbohydrate antigens, which permit classification into groups (Lancefield’s streptococcal groups A, B, C, D, F and G).  The streptococcal latex agglutination test contains latex particles that have been sensitized with group specific antibody and will agglutinate in the presence of homologous antigen.  In the absence of the particular antigen, the latex particles will remain in a smooth suspension.
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