This thesis is an investigation of methods to remediate methicillin-resistant Staphylococcus pseudintermedius (MRSP) biofilms through conventional and microfluidic-based in vitro assays. MRSP biofilm related infections are a major concern for veterinary clinicians as they may complicate remediation by the immune system or antimicrobials. Novel antimicrobials that have been found to reduce biofilm growth in other staphylococci were assessed in both mono- and combination therapy against MRSP biofilm. Quantitative assay results (p < 0.05) suggest fosfomycin alone and in combination with clarithromycin can significantly reduce biofilm formation. Morphological examination using scanning electron microscopy and atomic force microscopy further demonstrated the effectiveness of fosfomycin alone on biofilm formation on orthopaedic screws and mica sheets. Fabricated microfluidic assays were utilized to assess multiple concentrations of antimicrobial therapy against pre-formed biofilm under physiologically relevant conditions in a quick and repeatable manner. Results demonstrated the usefulness of microfluidic platforms in determining minimum biofilm eradication concentrations.

Thesis (M.S.)--University of Alabama at Birmingham, 2006. / Title from first page of PDF file (viewed Feb. 19, 2009). Includes bibliographical references (p. 35-44).

Thesis (M.S.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. "December 2008" Includes bibliographical references.

Vancomicina é o antimicrobiano de escolha no tratamento de bacteremias causadas por estafilococos resistentes à meticilina. No entanto, estudos recentes têm reportado que a vancomicina apresenta atividade reduzida contra Staphylococcus aureus resistentes à meticilina com concentrações inibitórias mínimas (CIMs) próximas do limite do ponto de corte de suscetibilidade, conforme critérios do CLSI, indicando falha terapêutica. Entretanto, existem poucos estudos à respeito dos Staphylococcus sp. coagulase negativa resistentes à meticilina (SCoNRM). Ademais, para determinação da CIM, deveria ser utilizado o método de referência microdiluição em caldo (MDC), mas a maioria dos laboratórios clínicos utiliza a técnica de Etest ou sistemas automatizados. Alguns estudos com S. aureus demonstraram discrepâncias entre MDC e Etest, contudo não existem dados referentes aos SCoN. Os objetivos deste estudo foram avaliar a correlação entre as CIMs de vancomicina determinadas pelas técnicas de MDC e Etest em 130 SCoNRM isolados de hemocultura, bem como verificar a relação entre valores de CIM e falha terapêutica entre pacientes com bacteremia por SCoNRM tratados com este antimicrobiano. A maioria dos resultados de CIM por MDC (98,5%) foram ≤1,0 mg/mL, enquanto o Etest apresentou 72,3% de CIM ≥ 1,5 mg/mL. As CIMs de vancomicina obtidas por Etest foram, em geral, uma a duas diluições maiores do que as CIMs obtidas por MDC. Os resultados indicam que a técnica de Etest gera valores de CIM consistentemente maiores do que os obtidos por MDC nos SCoNRM. Apenas 37 (28,5%) dos 130 pacientes com hemocultura positiva para SCoNRM apresentaram dados clínicos compatíveis com bacteremia. A maioria dos pacientes com bacteremia comprovada (n=24) apresentaram CIMs de vancomicina ≥1,5 mg/mL, sendo que 13 pacientes (35,1%) obtiveram CIM < 1,5 mg/mL. Este estudo não observou relação estatisticamente significativa entre valores de CIM de vancomicina que pudessem ser associados com falha terapêutica em pacientes com bacteremia por SCoNRM. / Vancomycin is the first-line therapy for methicillin-resistant staphylococci bacteremia. However, recent studies have reported that vancomycin demonstrates reduced activity against methicillin-resistant Staphylococcus aureus bacteremia, with vancomycin MICs at the high end of the CLSI susceptibility range indicating treatment failure. There is, however, little data considering methicillin-resistant coagulase-negative staphylococci (MRCoNS) bacteremia. Besides, the reference method that should be used for MIC determination is the broth microdilution (BMD), but many clinical laboratories use the commercial Etest technique or automated systems. Some reports have showed a growing number of vancomycin MIC discrepancies between BMD and Etest method for S. aureus, but there are no studies about CoNS. The aims of this study were to evaluated the correlation between the vancomycin MIC determined by the Etest and the BMD method for a total of 130 MRCoNS bloodstream isolates as well as to examine the relationship between vancomycin MICs and failure among patients with MRCoNS bacteremia treated with vancomycin. The vast majority (98.5%) of MIC results by BMD were ≤1.0 mg/mL in contrast to MIC by Etest which majority (72.3%) was ≥1.5 mg/mL. The vancomycin MICs obtained by the Etest for the same isolates were, in general, one to twofold higher than those obtained by the BMD method. The results indicate that the Etest provides vancomycin MIC values consistently higher than those obtained by BMD method for MRCoNS. Only 37 (28.5%) out of the 130 patients with a positive MRCoNS bloodstream culture met the eligibility criteria to be considered bacteremic. The majority of these patients (n = 24, 64.9%) presented vancomycin MIC ≥ 1.5 mg/mL, in opposite to 13 patients (35.1%) with MIC < 1.5 mg/mL. This study did not observe any statistical significative relationship between vancomycin MIC and treatment failure.

Introdução: a colonização de indivíduos com HIV/aids por microrganismos patogênicos tem sido associada a maior risco de morbidade e mortalidade, principalmente quando esse microrganismo é o Staphylococcus aureus. Identificar precocemente esta condição permite implementar medidas preventivas do adoecimento a ele relacionado, em nível individual e coletivo. Objetivo: avaliar a prevalência de colonização por Staphylococcus aureus em indivíduos com HIV/aids internados em um hospital escola. Metodologia: estudo de corte transversal, tendo como sujeito pessoas vivendo com HIV/aids, internadas em duas unidades especializadas em HIV/aids de um Hospital Escola do município de Ribeirão Preto- SP. Todos os preceitos éticos foram criteriosamente respeitados. No período de Agosto/2011 a Julho/2012, todos os indivíduos internados foram abordados e para aqueles que aceitaram participar, procedeu-se a coleta de amostra de saliva e secreção nasal, além da coleta de dados sociodemográficos, clínicos e imunológicos, obtidos por meio do prontuário e entrevista individual. As amostras foram encaminhadas e processadas pelo Laboratório de Microbiologia e Sorologia da instituição em estudo. Foram semeadas em meios de cultura ágar sangue e manitol, e após, transferidas para o sistema automatizado Vitek® 2 (BioMérieux(TM)), por meio dos cartões GP Test Kit Vitek® 2, para bactérias gram-positivas. Foram empregados cartões AST-P585 para avaliar a sensibilidade dos Staphylococcus aureus meticilina resistente (MRSA) aos antibióticos. Os dados foram armazenados em planilhas do Microsoft Office Excel 2011 for Mac e organizados por meio do software Statistical Package for the Social Sciences (SPSS), versão 17.0 for Windows. Resultados: De 229 indivíduos com HIV/aids internados nas unidades, 169 constituíram os sujeitos desta pesquisa, dos quais 57,4% eram do sexo masculino, 39,6% apresentaram idade de 40 a 49 anos e 45% tinham o primeiro grau completo. Foram obtidas 338 amostras (169 de secreção nasal e 169 de saliva). A prevalência de colonização por Staphylococcus aureus foi identificada em 20,4% das amostras, com 21,7% de resistência à oxacilina, sendo em secreção nasal 66,7% e em saliva 33,3%. Apresentaram contagem de linfócitos T CD4 abaixo de 200 células/mm3 60,0% dos indivíduos com MRSA nasal e 80,0% estavam em uso de antimicrobianos. Em 40,0% dos indivíduos com MRSA na saliva carga viral foi igual ou superior a 500.001 cópias/mL, e 80,0% destes também usavam antimicrobianos, MRSA nasal e saliva foi identificado em 60,0% dos indivíduos que não estavam em uso de antirretroviral. Conclusão: a prevalência de colonização por Staphylococcus aureus em indivíduos com HIV/aids foi predominante em secreção nasal, com baixa contagem de linfócitos T CD4, com história de internação prévia, uso de antimicrobiano e ausência do uso de antirretroviral, podendo representar importante fonte de infecção. / Introduction: colonization by pathogenic microorganisms in individuals with HIV/AIDS has been associated with increased risk of morbidity and mortality, especially when that organism is Staphylococcus aureus. Early identification of this condition allows implementing preventive measures of illness related to it, both individually and collectively. Objective: to evaluate the prevalence of Staphylococcus aureus colonization in individuals with HIV/AIDS in a teaching hospital. Method: cross-sectional study; the subjects were people living with HIV/AIDS and hospitalized in two specialized HIV/AIDS care units of a Teaching Hospital in the city of Ribeirão Preto. All ethical principles were carefully observed. In the period from August 2011 to July 2012, all subjects hospitalized were approached and, for those who agreed to participate, the collection of saliva and nasal discharge sample was performed, in addition to collecting sociodemographic, clinical and immunological data, obtained through medical record and individual interviews. The samples were forwarded and processed by the Laboratory of Microbiology and Sorology of the institution. They were seeded in blood agar and mannitol-salt-agar culture medium, and thereafter, transferred to the automated system Vitek® 2 (BioMérieux(TM)) through Vitek® 2 Test Cards for Gram-positive bacteria. AST-P585 cards were used to assess the sensitivity of methicillin-resistant Staphylococcus aureus (MRSA) to the antibiotic. Data were stored in spreadsheets of Microsoft Office Excel 2011 for Mac and organized by the Statistical Package for the Social Sciences (SPSS) version 17.0 for Windows. Results: of the 229 individuals with HIV/AIDS hospitalized in the units, 169 were the subjects in this study, of whom 57.4% were male, 39.6% were aged from 40 to 49 years, and 45% had completed elementary school. 338 samples were collected (169 of nasal discharge and 169 of saliva). The prevalence of Staphylococcus aureus colonization was identified in 20.4% of samples, with 21.7% of oxacillin resistance, being 66.7% in nasal discharge and 33.3% in saliva. 60.0% of individuals with MRSA in nasal had lymphocytes T CD4 count below 200 cells/mm3 , and 80.0% were taking antimicrobials. In 40.0% of the individuals with MRSA in saliva, the viral load was equal or higher than 500.001 copies/mL, and 80.0% of these also used antimicrobials; MRSA in nasal and in saliva were detected in 60.0% of individuals who were not taking antiretroviral. Conclusion: the prevalence of Staphylococcus aureus colonization in individuals with HIV/AIDS was prevalent in nasal discharge, had lymphocytes T CD4 low count, with a history of previous hospitalization, antimicrobial use and the absence of antiretroviral use, and it may represent an important source of infection.

Vancomycin is one of the most extensively used antibacterial agents for the treatment of severe gram positive infections including methicillin-resistant Staphylococcus aureus. It is also known that the use of this antimicrobial is a risk factor for subsequent colonization or infection with vancomycin-resistant Enterococcus (VRE). This retrospective observational study was to evaluate the results of vancocinemias that were conducted in adult and pediatric patients hospitalized in the period january to november 2012 at the University Hospital of Santa Maria (HUSM). Were evaluated 353 vancocinemias performed in 115 patients. Of the total, 180 vancocinemias were collected in the TROUGH, of these 150 (83.33%) were above the recommended range, 20 (11.11%) were within the expected values and 10 (5.56%) showed lower than expected. The review was carried out in 26 patients at the PEAK, 15 (57.69%) showed lower serum concentrations recommended, 5 (19.23%) were within the range and 6 (23.08%) had values greater than those expected. The remaining 147 (41.64%), was not collected in strips of PEAK and TROUGH. These data confirm the importance and necessity of conducting a routine therapeutic monitoring of vancomycin, through the creation and implementation of a collection routine. / A vancomicina constitui-se em um dos agentes antibacterianos mais extensivamente utilizados para o tratamento de infecções severas de patógenos gram positivos envolvendo Staphylococcus aureus resistentes à meticilina. Sabe-se também que o uso desse antimicrobiano constitui fator de risco para subsequente colonização ou infecção por Enterococcus resistentes à vancomicina (VRE). Esse estudo observacional retrospectivo teve como objetivo avaliar os resultados das vancocinemias que foram realizadas nos pacientes adultos e pediátricos internados no período de janeiro a novembro de 2012 no Hospital Universitário de Santa Maria (HUSM). Foram avaliadas 353 vancocinemias realizadas em 115 pacientes. Do total, 180 (50,99%) vancocinemias foram coletadas no VALE, destas 150 (83,33%) estavam acima da faixa recomendada, 20 (11,11%) estavam dentro dos valores esperados e 10 (5,56%) apresentaram valores abaixo do esperado. O exame foi realizado em 26 (7,37%) pacientes no PICO, sendo que 15 (57,69%) apresentaram valores inferiores às concentrações séricas recomendadas, 5 (19,23%) encontravam-se dentro da faixa e 6 (23,08%) tiveram valores superiores aos esperados. O restante, 147 (41,64%), não foi coletado em faixas de PICO e VALE. Estes dados confirmam a importância e a necessidade da realização de uma rotina de monitoramento terapêutico da vancomicina, através da criação e implementação de uma de rotina de coleta.

Vancomicina é o antimicrobiano de escolha no tratamento de bacteremias causadas por estafilococos resistentes à meticilina. No entanto, estudos recentes têm reportado que a vancomicina apresenta atividade reduzida contra Staphylococcus aureus resistentes à meticilina com concentrações inibitórias mínimas (CIMs) próximas do limite do ponto de corte de suscetibilidade, conforme critérios do CLSI, indicando falha terapêutica. Entretanto, existem poucos estudos à respeito dos Staphylococcus sp. coagulase negativa resistentes à meticilina (SCoNRM). Ademais, para determinação da CIM, deveria ser utilizado o método de referência microdiluição em caldo (MDC), mas a maioria dos laboratórios clínicos utiliza a técnica de Etest ou sistemas automatizados. Alguns estudos com S. aureus demonstraram discrepâncias entre MDC e Etest, contudo não existem dados referentes aos SCoN. Os objetivos deste estudo foram avaliar a correlação entre as CIMs de vancomicina determinadas pelas técnicas de MDC e Etest em 130 SCoNRM isolados de hemocultura, bem como verificar a relação entre valores de CIM e falha terapêutica entre pacientes com bacteremia por SCoNRM tratados com este antimicrobiano. A maioria dos resultados de CIM por MDC (98,5%) foram ≤1,0 mg/mL, enquanto o Etest apresentou 72,3% de CIM ≥ 1,5 mg/mL. As CIMs de vancomicina obtidas por Etest foram, em geral, uma a duas diluições maiores do que as CIMs obtidas por MDC. Os resultados indicam que a técnica de Etest gera valores de CIM consistentemente maiores do que os obtidos por MDC nos SCoNRM. Apenas 37 (28,5%) dos 130 pacientes com hemocultura positiva para SCoNRM apresentaram dados clínicos compatíveis com bacteremia. A maioria dos pacientes com bacteremia comprovada (n=24) apresentaram CIMs de vancomicina ≥1,5 mg/mL, sendo que 13 pacientes (35,1%) obtiveram CIM < 1,5 mg/mL. Este estudo não observou relação estatisticamente significativa entre valores de CIM de vancomicina que pudessem ser associados com falha terapêutica em pacientes com bacteremia por SCoNRM. / Vancomycin is the first-line therapy for methicillin-resistant staphylococci bacteremia. However, recent studies have reported that vancomycin demonstrates reduced activity against methicillin-resistant Staphylococcus aureus bacteremia, with vancomycin MICs at the high end of the CLSI susceptibility range indicating treatment failure. There is, however, little data considering methicillin-resistant coagulase-negative staphylococci (MRCoNS) bacteremia. Besides, the reference method that should be used for MIC determination is the broth microdilution (BMD), but many clinical laboratories use the commercial Etest technique or automated systems. Some reports have showed a growing number of vancomycin MIC discrepancies between BMD and Etest method for S. aureus, but there are no studies about CoNS. The aims of this study were to evaluated the correlation between the vancomycin MIC determined by the Etest and the BMD method for a total of 130 MRCoNS bloodstream isolates as well as to examine the relationship between vancomycin MICs and failure among patients with MRCoNS bacteremia treated with vancomycin. The vast majority (98.5%) of MIC results by BMD were ≤1.0 mg/mL in contrast to MIC by Etest which majority (72.3%) was ≥1.5 mg/mL. The vancomycin MICs obtained by the Etest for the same isolates were, in general, one to twofold higher than those obtained by the BMD method. The results indicate that the Etest provides vancomycin MIC values consistently higher than those obtained by BMD method for MRCoNS. Only 37 (28.5%) out of the 130 patients with a positive MRCoNS bloodstream culture met the eligibility criteria to be considered bacteremic. The majority of these patients (n = 24, 64.9%) presented vancomycin MIC ≥ 1.5 mg/mL, in opposite to 13 patients (35.1%) with MIC < 1.5 mg/mL. This study did not observe any statistical significative relationship between vancomycin MIC and treatment failure.

Vancomicina é o antimicrobiano de escolha no tratamento de bacteremias causadas por estafilococos resistentes à meticilina. No entanto, estudos recentes têm reportado que a vancomicina apresenta atividade reduzida contra Staphylococcus aureus resistentes à meticilina com concentrações inibitórias mínimas (CIMs) próximas do limite do ponto de corte de suscetibilidade, conforme critérios do CLSI, indicando falha terapêutica. Entretanto, existem poucos estudos à respeito dos Staphylococcus sp. coagulase negativa resistentes à meticilina (SCoNRM). Ademais, para determinação da CIM, deveria ser utilizado o método de referência microdiluição em caldo (MDC), mas a maioria dos laboratórios clínicos utiliza a técnica de Etest ou sistemas automatizados. Alguns estudos com S. aureus demonstraram discrepâncias entre MDC e Etest, contudo não existem dados referentes aos SCoN. Os objetivos deste estudo foram avaliar a correlação entre as CIMs de vancomicina determinadas pelas técnicas de MDC e Etest em 130 SCoNRM isolados de hemocultura, bem como verificar a relação entre valores de CIM e falha terapêutica entre pacientes com bacteremia por SCoNRM tratados com este antimicrobiano. A maioria dos resultados de CIM por MDC (98,5%) foram ≤1,0 mg/mL, enquanto o Etest apresentou 72,3% de CIM ≥ 1,5 mg/mL. As CIMs de vancomicina obtidas por Etest foram, em geral, uma a duas diluições maiores do que as CIMs obtidas por MDC. Os resultados indicam que a técnica de Etest gera valores de CIM consistentemente maiores do que os obtidos por MDC nos SCoNRM. Apenas 37 (28,5%) dos 130 pacientes com hemocultura positiva para SCoNRM apresentaram dados clínicos compatíveis com bacteremia. A maioria dos pacientes com bacteremia comprovada (n=24) apresentaram CIMs de vancomicina ≥1,5 mg/mL, sendo que 13 pacientes (35,1%) obtiveram CIM < 1,5 mg/mL. Este estudo não observou relação estatisticamente significativa entre valores de CIM de vancomicina que pudessem ser associados com falha terapêutica em pacientes com bacteremia por SCoNRM. / Vancomycin is the first-line therapy for methicillin-resistant staphylococci bacteremia. However, recent studies have reported that vancomycin demonstrates reduced activity against methicillin-resistant Staphylococcus aureus bacteremia, with vancomycin MICs at the high end of the CLSI susceptibility range indicating treatment failure. There is, however, little data considering methicillin-resistant coagulase-negative staphylococci (MRCoNS) bacteremia. Besides, the reference method that should be used for MIC determination is the broth microdilution (BMD), but many clinical laboratories use the commercial Etest technique or automated systems. Some reports have showed a growing number of vancomycin MIC discrepancies between BMD and Etest method for S. aureus, but there are no studies about CoNS. The aims of this study were to evaluated the correlation between the vancomycin MIC determined by the Etest and the BMD method for a total of 130 MRCoNS bloodstream isolates as well as to examine the relationship between vancomycin MICs and failure among patients with MRCoNS bacteremia treated with vancomycin. The vast majority (98.5%) of MIC results by BMD were ≤1.0 mg/mL in contrast to MIC by Etest which majority (72.3%) was ≥1.5 mg/mL. The vancomycin MICs obtained by the Etest for the same isolates were, in general, one to twofold higher than those obtained by the BMD method. The results indicate that the Etest provides vancomycin MIC values consistently higher than those obtained by BMD method for MRCoNS. Only 37 (28.5%) out of the 130 patients with a positive MRCoNS bloodstream culture met the eligibility criteria to be considered bacteremic. The majority of these patients (n = 24, 64.9%) presented vancomycin MIC ≥ 1.5 mg/mL, in opposite to 13 patients (35.1%) with MIC < 1.5 mg/mL. This study did not observe any statistical significative relationship between vancomycin MIC and treatment failure.

Magister Scientiae (Medical Bioscience) - MSc(MBS) / Staphylococcus aureus is a Gram-positive coccus belonging to the Stapylococcaeae family. S. aureus causes a wide range of infections that range from skin infections to lifethreatening infections such as pneumonia and endocarditis and is the major cause of hospital and community-acquired infections. Despite antibiotics being available for the treatment of S.aureus infections, resistance to a number of antibiotics has developed over the years due to their improper and continuous use. S. aureus develops resistance to various drugs via different mechanisms, one of which is the extrusion of the antibiotics through efflux pumps that play a role in its acquisition of multidrug resistance. The ability of methicillin-resistant S.aureus to develop resistance to a variety of antibiotics is causing global concern as treatment options are being limited. Various antimicrobial studies carried out on purified plant-based flavonoids have shown that flavonoids enhance the antibacterial effect of antibiotics. This study analysed antibacterial effects of the antibiotics; tetracycline, ampicillin, methicillin and vancomycin and three flavonoids; chrysin, naringenin and 7-hydroxyflavone, against methicillin-sensitive ATCC 25923 (MSSA) and methicillin-resistant ATCC 33591 (MRSA) S. aureus strains, using the Kirby-Bauer disk diffusion and microtitre microdilution assays. In the Kirby- Bauer assay, the antibiotics demonstrated inhibitory effects on the growth of MSSA ATCC 25923. However MRSA ATCC 33591 was only susceptible to vancomycin, with minimal inhibition zones observed with ampicillin. The flavonoids did not enhance or reduce the antibacterial activities of the antibiotics as the zones of inhibition sizes remained unchanged in the combination studies. Microtitre assay results revealed that naringenin enhanced the antibacterial activities of the antibiotics tetracycline and ampicillin, against MSSA ATCC 25923 and MRSA 33591. This was evident as calculated synergistic ratios by the Abbot formula showed that naringenin had an additive effect. The presence of the efflux pump genes in MSSA ATCC 25923 and MRSA ATCC 33591 was compared using polymerase chain reaction (PCR). The mepA and gyrA genes were identified in both strains whereas sepA was identified in MRSA ATCC 33591. The presence of efflux pump genes in both MSSA ATCC 25923 and MRSA ATCC 33591 also confirmed that the presence or absence of the genes may contribute to antibiotic resistance. The presence of sepA in the MRSA and not the MSSA confirmed that this gene plays a role in conferring drug resistance.

Methicillin-resistant Staphylococcus aureus (MRSA) are reported worldwide as a high prevalence of pathogens in the etiology of infections, both nosocomial and community. This study aimed to determine the prevalence of MRSA in the University Hospital of Santa Maria (HUSM), 2007-2011, as well as evaluating the sensitivity to vancomycin front of MRSA isolates collected from May to December 2011. We analyzed retrospectively the clinical data of all patients diagnosed with MRSA infections between January 2007 and December 2011. During this period, 1,852 samples of S. aureus foram isolated in HUSM, and 616 (33.3%) were resistant to oxacillin. There was a significant reduction in the prevalence rates of this pathogen which rose from 43.4% in 2007 to 33.9% in 2008, 30.4% in 2009, 28.1% in 2010 and 27.5% in 2011. Infections were more prevalent in male patients, aged 41 to 70 years, hospitalized in Medical clinic (16.28%), Adult Intensive Care Unit (15.13%), First Aid Post (13%), Adult Emergency Care (12.67%) and Surgery Clinic (12.5%). A greater isolation of MRSA in blood samples (16.9%), followed by tracheal aspirates (16.5%), urine (10.4%), sputum (8.7%), surgery wound secretion (8.1%) and lower limb secretion (7.8%). As for the determination of susceptibility to vancomycin, 125 samples from S. aureus were collected prospectively from May to December 2011, which 31 (24.8%) were MRSA. The minimum inhibitory concentration (MIC) of vancomycin was determined using a conventional methodology manual broth microdilution. The MIC most frequent among all S. aureus were the 1μg/mL, presented by 53.6% of the strains, whereas among MRSA, there was a higher frequency of MIC of 2 mg/mL (48.4%). Therefore all isolates belonging to this study were sensitive to this antimicrobial of choice for infections caused by MRSA strains. Thus, given the high rates of morbidity and mortality associated with these infections, this study demonstrated the importance of recognizing the prevalence and profile of susceptibility to vancomycin of MRSA so that effective measures for the treatment and control of MRSA to take effect. / Staphylococcus aureus resistentes à meticilina (MRSA) são relatados mundialmente como patógenos de elevada prevalência na etiologia de infecções, tanto nosocomiais como comunitárias. Este trabalho teve por objetivo determinar a prevalência dos MRSA no Hospital Universitário de Santa Maria (HUSM), de 2007 a 2011, bem como avaliar o perfil de sensibilidade frente à vancomicina de isolados de MRSA, coletados de maio a dezembro de 2011. Analisaram-se retrospectivamente, dados clínicos de todos os pacientes diagnosticados com infecções por MRSA entre janeiro de 2007 e dezembro de 2011. Durante este período, 1.852 amostras de S. aureus foram isoladas no HUSM, sendo que 616 (33,3%) foram resistentes à oxacilina. Houve uma redução significativa nas taxas de prevalência deste patógeno que passou de 43,4% em 2007 para 33,9% em 2008, 30,4% em 2009, 28,1% em 2010 e 27,5% em 2011. As infecções foram mais prevalentes em pacientes do sexo masculino, com idades entre 41 e 70 anos, internados na Clínica Médica (16,28%), Unidade de Terapia Intensiva adulto (15,13%), Ambulatório (13%), Pronto Atendimento adulto (12,67%) e Clínica Cirúrgica (12,5%). Houve maior isolamento dos MRSA em amostras de sangue (16,9%), seguido de secreção traqueal (16,5%), urina (10,4%), escarro (8,7%), secreção de ferida operatória (8,1%) e de membro inferior (7,8%). Já para a determinação da sensibilidade à vancomicina, foram coletadas prospectivamente 125 amostras de S. aureus de maio a dezembro de 2011, das quais 31 (24,8%) foram MRSA. A concentração inibitória mínima (CIM) da vancomicina foi determinada através de metodologia convencional manual de microdiluição em caldo. A CIM mais frequente dentre todos os S. aureus foi a de 1μg/mL, apresentada por 53,6% das cepas, enquanto que dentre os MRSA, houve maior frequência da CIM de 2 μg/mL (48,4%). Portanto todos os isolados pertencentes ao presente estudo foram sensíveis a este antimicrobiano de escolha para infecções causadas por cepas MRSA. Desta forma, diante das altas taxas de morbidade e mortalidade associadas a estas infecções, este estudo demonstrou a importância do reconhecimento da prevalência e do perfil de sensibilidade à vancomicina dos MRSA, para que medidas eficazes para o tratamento e controle dos MRSA sejam efetivadas.