Staphylococcus aureus (including MRSA)

Please note: This is for information only.

Refer to local guidelines for treatment recommendations


  • A Gram-positive coccus that is often found colonising on the skin of the anterior nares, axilla, and perineum.
  • The methicillin (flucloxacillin) resistant version (MRSA) is a particular infection control hazard.
  • S. aureus in general, (MRSA or MSSA) is a common agent of nosocomial infections in hospitals.
  • Currently, between 40-50% of healthcare-associated S aureus infections are due to MRSA, but <5% of true community S aureus infections

Main clinical infections:

  • Skin and soft tissue infections (impetigo, cellulitis)
  • Surgical ward infections
  • Venflon infections
  • Intravascular catheter infections (often with bacteraemia).
  • Severe systemic infections in deep foci such as endocarditis, osteomyelitis, myositis, and fasciitis.

MSSA: Usually sensitive to:

  • Flucloxacillin
  • Co-amoxiclav
  • 1st and 2nd generation cephalosporins
  • Gentamicin
  • Erythromycin
  • Doxycycline
  • Fusidic acid
  • Rifampicin
  • Clindamycin
  • Trimethoprim
  • Vancomycin
  • Seek microbiology advice for synergistic drug combinations in severe infections.

MSSA: Usually resistant to:

  • Benzylpenicillin
  • Amoxicillin
  • Ceftazidime
  • MRSA: (multiple-resistant organism): Usually sensitive to:
  • Vancomycin (1st line choice for i.v. therapy)
  • Doxycycline (1st choice for p.o. therapy in less severe infections)
  • Teicoplanin
  • Gentamicin (Gentamicin resistance in MRSA is thankfully uncommon in Nottingham.)
  • Trimethoprim
  • Fusidic acid
  • Rifampicin

MRSA: Usually resistant to:

  • All beta-lactam antibiotics (e.g. penicillins, flucloxacillin, cephalosporins, co-amoxiclav, imipenem),
  • Quinolones (e.g. ciprofloxacin and levofloxacin),
  • Macrolides (erythromycin, clarithromycin)