Micropara Lab (FINALS)

• Alpha hemolytic - RBC are seen dispersed throughout hemolytic area, partial hemolysis
• Beta hemolytic - free of RBC in the hemolytic are, complete hemolysis
• Lancefield classification - serological method for classifying streptococci into groups
• Group A

  • beta hemolysis
  • bacitracin susceptible
  • RYR test positive
  • causes strep throat and skin infection
  • Streptococcus pyogenes
• Group B

  • beta hemolysis
  • bacitracin resistant
  • hippurate utilized
  • CAMP test positive
  • Streptococcus galactiae
• Group C

  • alpha, beta, or non-hemolytic
  • growth in 6.5% of NaCl
  • PYR test positive
  • lacks group A and B antigens
  • Streptococcus equisimilis, Streptococcus dysgalactiae
• Group D

  • alpha or non-hemolytic
  • no growth in 6.5% of NaCl
  • non-enterococcal and enterococcal species
  • Enterococcus faecalis, Enterococcus faecium, Streptococcus bovis
• Non-groupable

  • alpha hemolytic
  • bile soluble
  • inhibited by optochin
  • Streptococcus pneumoniae
• Non-groupable 2

  • alpha hemolytic
  • not bile soluble
  • not inhibited by optochin
  • Viridians group
• Bacitracin susceptibility test

  • to differentiate GAS from other B-hemolytic Streptococci
  • to observe pattern of bacitracin susceptibility
• CAMP Reaction

  • Christie-Atkins-Munch-Peterson Test
  • to differentiate Streptococcus galactiae from other B-hemolytic Streptococci
  • detects the ability of an organism to produce camp factor
  • B-hemolysin + Camp factor = synergistic hemolysis
  • enhance after 30mns of adding camp factor reagent
• Bile esculin hydrolysis

  • to differentiate Enterococci and Group D streptococci from non-groupable viridians
  • ability to hydrolize esculin
  • enzymatic action of esculinase gives the presence of bile salt
• Hippurate hydrolysis

  • ability to hydrolyze hippurate into glycine and benzoic acid by the enzymatic action of hippuricase
• ASTO/ASO Test

  • Antistreptolysin O test
  • to detect antibodies against Streptolysin O in the blood serum of the patients
  • if there's the presence of the antibodies, it neutralizes the Streptolysin O
• Streptolysin - a pore forming toxin that is released by streptococci
• Streptolysin O - oxygen labile toxin that can lyse RBC, WBC, and platelets
• Streptolysin S - oxygen stable toxin with similar lytic properties to SLO, contributes to tissue destruction and immune invasion
• Pyrogenic Exotoxin - heat stable toxins produced by GAS, also called erythrogenic toxins.
• Streptococcal Superantigens - can stimulate excessive immune responses by binding to major histocompatibility complex class II molecules and T-cell receptors
• Streptokinase - facilitates the conversion of plasminogen to plasmin, which in turn degrades fibrin clots.
• Hyaluronidase - an enzyme that degrades hyaluronic acid in connective tissues. This facilitates the spread of bacteria through tissues by breaking down the extracellular matrix.
• Deoxyribonuclease - an enzyme that breaks down DNA, aiding in tissue invasion and dissemination by facilitating the breakdown of extracellular DNA, which can form a barrier to bacterial speed.