Despite the vigilance of physicians and public-health officials and the prompt treatment of positive carriers, community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) has been making a slow but steady trek across North America. But the CA-MRSA you’re likely to find in a primary-care clinic is not the same as the superbugs that are a leading cause of morbidity and mortality in institutionalized and hospitalized patients. Whereas that serious threat, known as healthcare-associated MRSA, still requires isolation and intensive treatment, GPs can effectively control CA-MRSA in outpatients with very simple and inexpensive measures.

Take aim

For the majority of patients who present with skin and soft tissue infections (SSTIs), simply exteriorizing abscesses and using local hygiene and oral antibiotics should effectively control their infections. If your conventional weapons — such as beta-lactam therapy — don’t work, or your patient is in a high-risk subpopulation for CA-MRSA, like athletes or intravenous drug users, or if you’re in a community where 10-15% of S. aureas isolates are resistant to methicillin, then you may have a drug-resistant strain on your hands (hopefully not literally) and you’ll have to get out the heavy artillery.

Most Canadian CA-MRSA strains are resistant to erythromycin, and quinolone therapy often fails against S. aureus. Topical antiseptics or antibiotics like bacitracin usually suffice for mild skin and soft tissue infections in less vulnerable groups. Clindamycin or TMP-SMX are the choices in moderate SSTIs, and in mild SSTIs among the young or immunocompromised. The most severe infections are treated with IV vancomycin. Sometimes cloxacillin or a 1st generation cephalosporin are added, while awaiting lab results.

Fire

Don’t neglect the nose, where S. aureus is common and which may serve as the reservoir for repeat infections. For fighting CA-MRSA in the nostrils, mupirocin has better minimal inhibitory concentrations (MICs) than fusidic acid. Treatment should be guided by clinical experience and nasal swabbing. Any recommended length of treatment is based more on local folklore than on clinical studies: a straw poll of ID experts produced answers ranging from 2 to 6 weeks.

Keep it pinned down

Decolonization is a theoretical goal, but is rarely — if ever — achieved. Studies that tested aggressive decolonization protocols were able to identify recolonization in the majority of patients within 6 months.