[Antibiotic susceptibility of Staphylococcus aureus strains responsible for community-acquired skin infections]

The appearance and worldwide spread of community-acquired methicillin-resistant Staphylococcus aureus (MRSA) skin infections warrant new studies of antibiotic resistance among strains of S. aureus responsible for cutaneous infections seen in general practice.

A prospective, multicentre study was performed from December 2003 to August 2004 in outpatients of both sexes presenting with a common bacterial skin infection presumed due to S. aureus (primary or secondary impetigo, ecthyma, paronychia, folliculitis, furunculosis). The investigators (n=50) were GPs from seven French regions. Clinical data (history, previous hospitalisation, type of infection, site, previous treatment, etc.) were collected using a standard questionnaire. A bacteriological sample was taken in attempt to isolate S. aureus after which antibiograms were prepared and minimal inhibiting concentrations determined (11 antibiotics).

Four hundred and eighty patients of mean age 42 years (range: 2-94 years) were included. S. aureus was isolated from cultures in 205 of 477 samples, i.e. in 197 patients (eight had two strains of S. aureus). Patients with S. aureus had a primary skin infection in 104/197 cases (53%) (24 impetigo, 20 paronychia, 45 folliculitis or furunculosis) and a secondary infection in 93/197 cases (47%), with 4.9% patients being hospitalized within the preceding six months (median: 10 days). Percentages of resistant S. aureus strains were as follows: penicillin: 86%, erythromycin: 32%, ciprofloxacin: 9.3%, tetracycline: 5.8%, oxacillin: 5.8% (representing MRSA strains), fusidic acid: 4.4%, clindamycin: 3.4%, mupirocin: 1% and gentamicin: 0.5%. All S. aureus strains were sensitive to vancomycin and rifampicin. Except for one strain also resistant to tetracycline and fusidic acid, all MRSA strains were also resistant to ciprofloxacin.

Multiresistant bacterial strains could become a concern in the community in France in the near future. In our study, only 14/197 (6.8%) S. aureus strains were sensitive to all tested antibiotics, whereas 21/197 (10.7%) were resistant to at least three of them. Compared to a French study performed in private practice in 2000, the level of MRSA is growing only slowly (5.8% versus 3.9%), whereas the percentage of strains of Peni-R/Oxa-S S. aureus are stable (80.5%).

Common bacterial infections of the skin due to MRSA or to multiresistant S. aureus are not rare in France and have tended to increase slowly in recent years.