GRAM+ COCCI

• What are the genera listed under MICROCOCCACEAE?


  Staphylococcus, Micrococcus, Planococcus, Stomatococcus
• What are the laboratory tests used for identifying Micrococcaceae and Staphylococcus species?


  1. Gram Stain
  2. Growth on BAP (Blood Agar Plate)
  3. Growth on LSS (Lysostaphin Slant)
  4. Growth on MSA (Mannitol Salt Agar)
  5. Catalase Test
  6. Coagulase
  7. DNAse Test
  8. Novobiocin Sensitivity Test
• What is the result of the Gram stain for Staphylococcus?


  It appears as clusters of Gram-positive cocci.
• What does the Tube Coagulase Test detect?

  It detects the presence of coagulase enzyme.
• What are the types of hemolysis observed on BAP?


  Alpha, Beta, Gamma hemolysis, and Alpha prime
• What color indicates Alpha hemolysis on BAP?


  Greenish discoloration around colonies.
• What color indicates Beta hemolysis on BAP?


  Complete clearing around colonies.
• What does Gamma hemolysis indicate on BAP?


  No change in color around colonies.
• What is the appearance of S. aureus on (LSS) Loeffler's Serum Slant?


  Golden yellow colonies.
• What is the significance of 7.5% Sodium Chloride in the growth medium?


  It acts as an inhibitor for non-staphylococci.
• What does MSA stand for?


  Mannitol Salt Agar.
• What does a yellow color indicate on MSA?


  It indicates mannitol fermentation.
• What does a pink color indicate on MSA?


  It indicates non-mannitol fermenting organisms.
• What is the result of the DNAse test for positive organisms?


  Clear zone around the growth.
• What does Novobiocin sensitivity test differentiate?


  It differentiates S. saprophyticus from S. epidermidis.
• What is the significance of the Catalase Test?


  It differentiates between Staphylococcus (catalase positive) and Streptococcus (catalase negative).
• What is the reagent used in the Catalase Test?


  3% Hydrogen Peroxide (H2O2).
• What is the most important determinant of S. aureus?


  Coagulase enzyme.
• What is the function of Staphylokinase?


  It dissolves fibrin clots.
• What does Hyaluronidase do?


  It hydrolyzes hyaluronic acid in connective tissue.
• What is the role of leukocidins?


  They lyse neutrophils and macrophages.
• What is the function of enterotoxins?


  They cause food poisoning and toxic shock syndrome.
• What are the characteristics of Streptococci?


  • Gram-positive cocci occurring in pairs or chains
  • Nonmotile
  • Non-spore forming
  • Facultative anaerobes
  • Catalase negative
• What is the Lancefield classification used for?


  It classifies Streptococci by antigenic character of group-specific cell wall polysaccharides.
• What are the types of hemolysis in Streptococci?


  Alpha, Beta, and Gamma hemolysis.
• What is the result of the Gram stain for S. pneumoniae?


  It appears as lancet-shaped Gram-positive diplococci.
• What does bile esculin hydrolysis test for?

  It tests the ability to grow in 40% bile esculin hydrolysis
• What is the result of bile esculin hydrolysis for Group D Streptococci?


  Black precipitate formation.
• What does the PYR test indicate?


  It indicates the presence of Group D Enterococci and Group A.
• What is the CAMP reaction used for?


  It is used to identify Group B Streptococci.
• What does Hippurate hydrolysis test for?


  It tests for Group B Streptococci.
• What is the significance of Bacitracin and SXT sensitivity tests?


  They help differentiate between Streptococcus species.
• What are the characteristics of Nutritionally Variant Streptococci?


  • Require vitamin B6 or pyridoxal
  • Known as satelliting streptococci
  • Thiol-requiring streptococci
• What is the significance of Taxo P in microbiology?


  It is used for the identification of Streptococcus pneumoniae.
• What are the pathogenic determinants of S. aureus?


  1. Protein A
  2. Coagulase
  3. Staphylokinase
  4. Lipase
  5. Hyaluronidase
  6. DNAse
  7. Exfoliatins
  8. Leukocidins
  9. Hemolysins

  10. Enterotoxins
• What is the function of Protein A in S. aureus?


  It helps in evading the immune response.
• What does lipase do in S. aureus?


  It hydrolyzes lipids in plasma and skin.
• What is the result of the DNAse test for S. aureus?


  Positive result shows a clear zone around the growth.
• What is the role of hemolysins in S. aureus?


  They lyse erythrocytes.
• What is the significance of enterotoxins produced by S. aureus?


  They are responsible for food poisoning and toxic shock syndrome.