Antibiotic sensitivity

Many Staph. aureus infection do not require antibiotics - the drainage of pus and removal of foreign bodies may be sufficient. The following must be noted when antibiotics are indicated:

• 85 % of strains produce a beta lactamase and show resistance to penicillin, amoxycillin and ampicillin
• 99 % are sensitive to flucloxacillin which is stable to beta lactamase activity. Methicillin was the first of this type of antibiotic to be developed and is often used to test flucloxacillin sensitivity in the laboratory.

Other useful antibiotics include:

• erythromycin - in penicillin allergy or mixed strep, infections; fusidic acid; and gentamicin

Less predictable antibiotics include Augmentin - contains clavulanic acid, a beta lactamase inhibitor; cephalosporins - not degraded but less active; tetracycline - but 10% strains are resistant; and ciprofloxacin - usually inadequate.

Topical agents such as chlorhexidine, povidone-iodine, and mupirocin are useful for impetigo and clearance of MRSA carriage.