Prevalence of methicillin resistant Staphylococcus aureus in skin and soft tissue infections, in ambulatory patients

Prevalence of methicillin resistant Staphylococcus aureus in skin and soft tissue infections, in ambulatory patients. An increased prevalence of community-acquired methicillin resistant Staphylococcus aureus (MRSA) in skin and soft tissue infections (SSTI) has been recently reported. Epidemiological data in Argentina is limited. Our objectives were to evaluate etiological agents, clinical presentation, risk factors and evolution of SSTI in ambulatory patients, in a descriptive and prospective study that was performed at the Infectious Diseases Department, Hospital Fernandez, City of Buenos Aires, Argentina, from 10/01/2009 to 01/31/2011. A total of 130 samples were analyzed from 130 patients. Median age: 36 years old (IQR 25.9-43.5); 61.5% were men. HIV infection: 46.9%. Positive cultures were obtained from 100 samples (76.9%): S. aureus 83, Streptococcus spp. 8, and other microorganisms 9. Sixty two (74.7%) of S. aureus isolates were oxacilin resistant, 12 (14.4%) clindamycin resistant, 14 (16.7%) erythromycin resistant and 5 (6%) ciprofloxacin resistant. Some samples presented more than one resistance. All were susceptible to rifampicin and minocycline and 98.8% (82) to trimethoprim-sulfamethoxazole. Of the MRSA patients, 83.8% (52) had at least one risk factor. No significant differences were found in relation to patients with bacterial infections different from MRSA. The most frequent clinical presentation of MRSA-SSTI was furuncle; 56.5% (35/62) vs. 28.9% (11/38) in other SSTI isolations (p = 0.013). Oxacilin resistance was similar among HIV positive and negative patients (79.1 vs. 70%, p = 0.179) (34/43 vs. 28/40). In conclusion: a high prevalence of MRSA was found in this population, irrespective of HIV serology or the presence of risk factors. Empirical treatment options for this microorganism are minocycline and trimethoprim-sulfamethoxazole.