Incidence and seasonal distribution of methicillin-resistant Staphylococcus aureus in adult outpatients at a clinic in Buenos Aires province: period 2006 to 2011

Incidence and seasonal distribution of methicillin-resistant Staphylococcus aureus in adult outpatients at a clinic in Buenos Aires province: period 2006 to 2011. In the last decade there was a significant growth of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA). We herein describe the annual incidence, seasonal distribution, antimicrobial resistance and phenotypes of MRSA in adult outpatients. From January 2006 to December 2011, 173 strains of S. aureus were studied, 77 (45%) of which were MRSA. The annual incidence per 100 processed materials increased from 0.13 in 2006 to 0.62 in 2011 due to the oxacillin-resistant phenotype, showing peaks in spring-summer until December 2008 and subsequent peaks in autumn-winter. The antimicrobial resistance profile was: erythromycin 24 (31 %), clindamycin 22 (29 %), gentamicin 23 (30 %), ciprofloxacin 13 (17 %), trimethoprim-sulfamethoxazole 3 (4 %), chloramphenicol 2 (3 %), rifampicin 2 (3 %), and minocycline 0. Sixteen phenotypes were identified; the oxacillin-resistant phenotype being the most common, accounting for 53 % (41 isolates) and exhibiting an increase ranging from 31 % to 65 %. The empirical treatment of infections was changed and prevention measures were implemented among contacts.