Streptococcus

• Groups in Lancefield grouping


  • Group B Strep: S. Agalactiae
  • Group A Strep: S. pyogenes
  • Group C Strep: S. Dysgalactiae, S. Equi
  • Group D Non-enterococcus: S. Bovis group/S. Gallolyticus
  • Group D Enterococcus: E. Faecalis, E. Faecium
  • Viridans Strep (Lancefield A, C, F, G, N): S. Anginosus, Mutans, Mitis
• Catalase + and Catalase -

  • Catalase +: Staphylococcus
  • Catalase -: Streptococcus
• Lancefield grouping

  Performed based on agglutination by performing serological testing
• Hemolysis types

  • Alpha hemolysis: partial lysis of RBC or a greenish discoloration around colony
  • Gamma hemolysis: non-hemolysis, no lysis of RBC, no change
  • Alpha prime: small area of intact RBC around the colony, wider zone of complete hemolysis
  • Beta hemolysis: complete lysis of RBC indicated by a clearing around the colony
• Mode of transmission of S. Pyogenes

  Inhalation and droplet transmission
• Hyaluronic acid capsule


  • Prevents opsonized phagocytosis and masks bacterial antigens
• Hyaluronic acid


  Solubilizes hyaluronic acid in connective tissues
• Bacterial pharyngitis and tonsillitis are connected to strep throat
• Streptolysin S


  Surface hemolysin, lysis of WBC, non-immunogenic
• Protein F


  • Mediates adherence to host epithelial cells
• Necrotizing fasciitis occurs if unable to eliminate pyodermal infections, attacking deeper tissues
• Erysipelas presents acute spreading erythematous lesions
• Scarlet fever is a pyodermal infection with diffuse red rashes
• Acute glomerulonephritis follows strep throat, deposition of Ab-ag complexes in glomeruli
• Streptococcus agalactiae has sialic acid and a capsule
• Lipoteichoic acid


  • Attachment to mucosal cells
• Bacterial classification

  • Staphylococcus: cluster
  • Streptococcus: chain
• Viridans Strep can be found in various areas such as the upper respiratory tract, gastrointestinal tract, or the vagina
• S. Pneumoniae is the only organism without Lancefield grouping
• M protein


  • Primary virulence factor of S. Pyogenes, attached on the cell wall causing infection
• Streptolysin O


  Responsible for the lysis of RBC, WBC, and platelets
• Streptococcus pyogenes is considered as not normal flora of the body
• Catalase test


  Differentiates Staphylococcus and Streptococcus through bubbles formation
• Streptokinase


  Causes lysis of fibrin clots
• Cellulitis is a pyodermal infection involving deeper tissue invasion
• Rheumatic heart fever results in inflammation of the heart and blood vessels
• Exotoxin A is associated with scarlet fever and streptococcal toxic shock-like syndrome
• S. Agalactiae causes pneumonia, sepsis, and menin
• Impetigo is a superficial and localized pyodermal infection
• Streptococcus agalactiae is normal flora of the vagina and can be found in the GIT
• Streptococcus agalactiae


  • Normal flora of the vagina and can also be found in the GIT
  • Has sialic acid and capsule
  • Causes pneumonia, sepsis, and meningitis to newborns
• Endometritis is inflammation of the uterine lining of females
• Bergey’s classification involves temperature requirements for bacterial growth
• Enterococcus


  • Has the capacity to resist antimicrobial agents specifically vancomycin
• Media for streptococci

  • Blood agar – enriched isolation agar
  • Blood agar with trimethoprim and sulfamethoxazole – selective media for beta-hemolytic streptococci
• SXT susceptibility results: positive for Group C and G; negative for Group A and B
• CAMP reaction positive results in enhanced hemolysis in arrowhead pattern
• Taxo A result: positive for Group A; negative for Group B, C, F, G
• Bile esculin hydrolysis positive result is indicated by blackening of the agar
• CAMP reaction


  Test for synergistic hemolysis between B strepto and beta-hemolytic S. aureus