streptococcus (13)

• What type of bacteria are Gram-positive cocci?

  Streptococcus spp.

  
• How are Gram-positive cocci arranged?

  In pairs or short/long chains

  
• What type of anaerobes are Gram-positive cocci?

  Facultative anaerobes
• What is the significance of fermentation and lactic acid production in Streptococcus mutans?

  It is important in dental caries
• What atmosphere favors the growth of Gram-positive cocci?

  5-10% CO2
• At what temperature do Gram-positive cocci grow in standard media?

  37 °C
• What type of media do Gram-positive cocci grow in?

  Standard nonselective media
• What is a characteristic of some species of Gram-positive cocci?

  Some are hemolytic
• How would you describe the group of Gram-positive cocci?

  Very heterogeneous group

  
• What is the catalase test result for Gram-positive cocci?

  Catalase negative
• What is the first classification scheme for Streptococcus spp.?

  Hemolytic patterns
• What are the hemolytic patterns of Streptococcus spp.?

  • α-hemolytic: incomplete hemolysis (green)
  • β-hemolytic: complete hemolysis (transparent)
  • γ-hemolytic: no hemolysis (red)
• Who proposed the Lancefield groupings?

  Rebecca Lancefield
• What do Lancefield groupings share?

  The same antigen 'group'
• Which Streptococcus species belongs to group A?

  1. pyogenes
• Which Streptococcus species belongs to group B?

  1. agalactiae
• Which group does Enterococci belong to?

  Group D
• Which Streptococcus species has no Lancefield antigens?

  Viridans streptococci group
• What is the habitat of viridans streptococci?

  Oropharyngeal cavity
• What dental issues are associated with viridans streptococci?

  Plaque formation and caries
• What serious infections can viridans streptococci cause outside the oral cavity?

  Endocarditis in neutropenic patients
• What is a characteristic of the Streptococcus mutans group?

  No capsule
• What is the role of glucans and glycosyltransferases in Streptococcus mutans?

  Involved in bacterial aggregation and plaque formation
• What type of fermentation does Streptococcus mutans perform?

  Lactate fermentation
• What is the cariogenicity factor of Streptococcus mutans?

  Synthesis of extracellular glucan
• What is the pH tolerance of Streptococcus mutans?

  Growth at low pH
• What is the cariogenic capacity of Streptococcus mitis group?

  Poor cariogenic capacity
• What is the treatment for viridans streptococci infections?

  Generally sensitive to penicillins
• What is the significance of the optochin test for Streptococcus pneumoniae?


  It differentiates it from viridans streptococci
• What type of infections is Streptococcus pneumoniae associated with?

  Respiratory and systemic infections
• What is a major cause of bacterial pneumonia?

  Streptococcus pneumoniae
• What is the structure of Streptococcus pyogenes?

  Teichoic acid and capsule
• What is the major virulence antigen of Streptococcus pyogenes?

  M protein
• What are the effects of the erythrogenic toxin produced by Streptococcus pyogenes?

  Causes rash of Scarlet Fever
• What is the role of streptokinase in Streptococcus pyogenes?

  Dissolves fibrin clots
• What type of infections does Streptococcus pyogenes cause?

  Suppurative and nonsuppurative infections
• What is a nonsuppurative disease caused by Streptococcus pyogenes?

  Acute rheumatic fever
• What is the treatment for Streptococcus pyogenes infections?

  Extremely sensitive to penicillin
• What is the prophylaxis for acute rheumatic fever?

  Penicillin