Staphylococcus aureus

• What type of pathogen is Staphylococcus aureus?

  Gram positive bacteria (superbug)
• What diseases are caused by Staphylococcus aureus?

  • Skin and Soft Tissue Infections (SSTIs)
  • Pneumonia
  • Bone and Joint Infections
  • Endocarditis
  • Bacteraemia and Sepsis
  • Toxic Shock Syndrome (TSS)
  • Staphylococcal Scalded Skin Syndrome (SSSS)
  • Food poisoning
• What are common causes of Skin and Soft Tissue Infections (SSTIs) by Staphylococcus aureus?

  Boils, abscesses, and cellulitis
• What is endocarditis associated with Staphylococcus aureus?

  Infection of heart valves in drug users
• What is the significance of bacteraemia and sepsis caused by Staphylococcus aureus?

  They can lead to septic shock
• What tissues are primarily affected by Staphylococcus aureus?

  Skin and soft tissue
• What are the primary loci of Staphylococcus aureus infections?

  • Skin (abscesses, cellulitis)
  • Respiratory tract (pneumonia)
  • Bloodstream (bacteremia, sepsis)
  • Bone and joints (osteomyelitis, septic arthritis)
  • Organs and devices (prosthetic infections, endocarditis)
• How is Staphylococcus aureus transmitted?

  Direct contact with infected wounds
• What are the risk factors for Staphylococcus aureus infections?

  Skin injuries and immunosuppression
• What other conditions have similar diseases to those caused by Staphylococcus aureus?

  • SSTIs: Streptococcus pyogenes
  • Pneumonia: Streptococcus pneumoniae, Klebsiella pneumoniae
  • Osteomyelitis: Pseudomonas aeruginosa, Salmonella spp.
  • Endocarditis: Viridans streptococci, Enterococcus spp., Candida spp.
  • Food poisoning: Clostridium perfringens, Bacillus cereus
• What are common symptoms of Staphylococcus aureus infections?

  Painful, swollen, red skin lesions
• What unique symptoms are associated with Staphylococcal Scalded Skin Syndrome (SSSS)?

  Desquamation of skin due to toxins
• What is a key symptom of toxic shock syndrome (TSS)?

  Hypotension and multi-organ failure
• What laboratory tests are used to identify Staphylococcus aureus?

  • Gram stain: Gram-positive cocci in clusters
  • Culture: Growth on blood agar or mannitol salt agar
  • Biochemical Tests: Catalase-positive, Coagulase-positive
  • Molecular Tests: PCR for toxin or resistance genes
• What can cause false positives in laboratory tests for Staphylococcus aureus?

  Contamination of cultures during collection
• What are the public health risks associated with Staphylococcus aureus?

  Leading cause of healthcare-associated infections
• What are the treatment options for Staphylococcus aureus infections?

  • MSSA: Beta-lactams (penicillins)
  • MRSA: Vancomycin, daptomycin, linezolid
  • CA-MRSA: Clindamycin or trimethoprim-sulfamethoxazole
• What is the mechanism of resistance in MRSA?

  Due to mecA gene encoding altered penicillin-binding protein (PBP2a).
• What is the significance of vancomycin-intermediate/resistant Staphylococcus aureus (VISA/VRSA)?

  Emergence of strains with reduced susceptibility
• What type of resistance is seen in some CA-MRSA strains?

  Resistance to fluoroquinolone and tetracycline