Staphylococcus

• What shape are G+ cocci?

  Spherical
• Name two types of G+ cocci.

  Staphylococci and Streptococci
• What are the two most common groups of G+ organisms of medical importance?

  Staphylococci and Streptococci
• What does the term "staphylococcus" mean in Greek?

  Bunch of grapes
• What is a key characteristic of Staphylococci regarding catalase?

  They are catalase-positive
• Why are Staphylococci considered hardy organisms?

  They survive quite well outside animal hosts
• What type of infections can Staphylococcus aureus cause?

  Infections can be trivial or rapidly fatal
• What color are the colonies of Staphylococcus aureus?

  Golden
• What is the significance of coagulase production in Staphylococcus aureus?

  It converts fibrinogen to fibrin, protecting from the immune system
• What does Protein A do in Staphylococcus aureus?

  It binds to IgG and prevents opsonisation

  
• What is the role of fibronectin-binding protein in Staphylococcus aureus?

  It promotes binding to mucosal cells and tissue matrices
• What are cytolytic exotoxins in Staphylococcus aureus known for?

  They attack mammalian cell membranes

  
• What is a superantigen exotoxin's effect in Staphylococcus aureus?

  It stimulates an enhanced T cell response

  
• What is the most common type of infection caused by Staphylococcus aureus?

  Localized skin infections
• What is impetigo and who is it most common in?

  It is a superficial, rapidly spreading infection, especially in children
• What can localized skin infections from Staphylococcus aureus lead to if untreated?

  They can lead to bacteraemia
• What is cellulitis in relation to Staphylococcus aureus infections?

  It is a localized skin infection involving the dermis and subcutaneous fat
• What are the major clinical significances of Staphylococcus aureus infections?

  Deep infections, septicaemia, endocarditis, and pneumonia
• What is toxic shock syndrome and its symptoms?

  It is a severe condition with fever, rash, vomiting, and multi-organ involvement
• What causes scalded skin syndrome in Staphylococcus aureus infections?

  It results from specific toxins leading to epithelial desquamation
• What is the treatment approach for destructive infections caused by Staphylococcus aureus?

  Aggressive treatments including source control and antibiotics
• What is the first-line antibiotic choice for Staphylococcus aureus infections?

  β-lactamase resistant lactams like flucloxacillin
• What is MRSA and where is it commonly found?

  MRSA is often healthcare-associated, found in hospitals and nursing homes
• What is the significance of PBP2a in MRSA strains?

  It is a mutation that leads to worse treatment outcomes
• What are coagulase-negative staphylococci (CNS)?

  They are staphylococci that are not Staphylococcus aureus
• What is Staphylococcus epidermidis known for?

  It is part of the normal flora and has lower virulence than S. aureus
• What is Staphylococcus saprophyticus associated with?

  It is associated with cystitis, especially in younger women
• What are the virulence factors of Staphylococcus aureus?

  • Protein A: Binds IgG, prevents opsonisation
  • Fibronectin-binding protein: Promotes binding to tissues
  • Cytolytic exotoxins: Attack cell membranes
  • Superantigen exotoxins: Enhance T cell response