High prevalence of community acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in skin and soft tissue infections in HIV positive patients
A. Duarte1, D. Ameri1, L. Errecalde2, M.E. Socías1, V. Bermejo1, J. Nuñez1, L. Spadaccini1, M. Cabrini1, P. Maldonado1, M.J. Rolón1, S. Kaufman2, H. Perez1, P. Cahn1
1Hospital Juan A. Fernández, Infectious Diseases Unit, Buenos Aires, Argentina, 2Hospital Juan A. Fernández, Microbiology Division, Buenos Aires, Argentina
Background: Various studies have reported methicillin-resistant Staphylococcus aureus (MRSA) as an emergent pathogen in skin and soft tissue infections (SSTIs) in HIV-positive patients. Data in Argentina is limited.
Objective: To evaluate MRSA prevalence in SSTIs caused by S. aureus in ambulatory HIV-positive patients, its clinical presentation, associated risk-factors and outcomes.
Methods: Retrospective, descriptive study of MRSA isolated from samples of SSTIs from HIV-positive patients assisted at the HIV reference center in Buenos Aires, Argentina from 2007 to 2009. Epidemiological features, clinical manifestations, antibiotic susceptibility, treatment and outcome were evaluated. Descriptive statistics and X2 were used.
Results: Out of 69 patients with S. aureus SSTI, in 50 (72.4%) MRSA was isolated. Gender: Male: 39, female 11. Median age: 39 (IQR 29-44), MSM 42.9%, heterosexual 30.6%, UDI 16.3%. Median CD4+ 331 cells/mm3 (IQR 131-520). On HAART 54%. Clinical manifestations: furuncles 46%, abscess 24%, folliculitis 12% and cellulites 12%. Empirical treatment was adequate in 51%. Outcome was favorable in 70% and unfavorable in 8%, with 2 patients requiring hospital admission, lost of follow-up 11 (22%). Antibiogram showed the following resistance pattern: macrolides 44%, clindamycin 38%, ciprofloxacin 8%, gentamicin 8%, rifampicin 2%, trimethoprim/sulfamethoxazol (TMP/SMX) 2%. Most of the isolates (43/50) were resistant to only one additional drug, on top of methicillin. The use of antimicrobials (mainly beta-lactams) in the previous 6 months was the only factor associated with MRSA SSTI (p=0.015). No association was found with age, risk behaviour, CD4 count, nor exposure to TMP/SMX prophylaxis.
Conclusions: CA-MRSA must be considered a possible etiology of SSTI in ambulatory HIV- positive patients. The proportion of samples showing resistance to macrolides and clindamycin precludes the empirical prescription of those antimicrobials in community-acquired SSTI in our population. TMP/SMX and rifampicin remain as options to be considered, particularly in patients previously exposed to antimicrobials.
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