Estudo do perfil populacional de Staphylococcus aureus resistente a meticilina de origem comunitária e hospitalar em hospital terciário, na busca de amostras hVISA

Abstract

Infections with methicillin-resistant Staphylococcus aureus (MRSA) are increasingly common, both in hospitals and in the community. Vancomycin is mainly used in treatment of microbial infections and, due to its indiscriminate use emerged strains with decreased susceptibility. In order to assess the presence of S. aureus with intermediate heteroresistant vancomycin (hVISA) in samples of MRSA from patients in the therapeutic use of this antimicrobial at the Clinical Hospital of Uberlândia Federal University (HC-UFU) in Uberlândia MG, we conducted a retrospective cohort study including 96 patients (48 patients who died and 48 patients discharged), between September 2006 and September 2008. The investigation of the occurrence of MRSA was performed from skin, soft tissues including pus, surgical site infection and bloodstream; inpatient or outpatient clinic of the hospital that were diagnosed with MRSA infection. Selected samples were tested for sensitivity to vancomycin by agar dilution techniques and heteroresistant by analysis of the population profile, in the area under the curve (AUC - PAP). The minimum inhibitory concentration (MIC) of 93.7 % of the samples exhibited MIC to vancomycin between 1 and 2μg/mL and 2% showed an MIC of 3μg/mL. The hVISA phenotype occurred more than a quarter of the samples of MRSA, although showing a high prevalence in conventional MIC indicated susceptibility to vancomycin. The prevalence of mortality was significant (P = 0.001), in patients with hVISA phenotype. The presence of vancomycin heteroresistant samples represents a potential risk in the future, and clinically supported multicenter studies should be performed in our country to clarify prevalence rates and to determine the clinical relevance of this phenotype.