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The aim of this study was to investigate the in vitro and in vivo efficacy and the tissue reaction of an antibiofilm coating composed of xylitol, triclosan, and polyhexamethylene biguanide. The antimicrobial activity was analyzed by a turbidimetric method. Scanning electron microscopy was used to evaluate the antiadherent property of central venous catheter (CVC) fragments impregnated with an antibiofilm coating (I-CVC) in comparison with noncoated CVC (NC-CVC) fragments. Two in vivo assays using subcutaneous implantation of NC-CVC and I-CVC fragments in the dorsal area of rats were performed. The first assay comprised hematological and microbiological analysis. The second assay evaluated tissue response by examining the inflammatory reactions after 7 and 21 days. The formulation displayed antimicrobial activity against all tested strains. A biofilm disaggregation with significant reduction of microorganism's adherence in I-CVC fragments was observed. In vivo antiadherence results demonstrated a reduction of early biofilm formation of Staphylococcus aureus ATCC 25923, mainly in an external surface of the I-CVC, in comparison with the NC-CVC. All animals displayed negative hemoculture. No significant tissue reaction was observed, indicating that the antibiofilm formulation could be considered biocompatible. The use of I-CVC could decrease the probability of development of localized or systemic infections.

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INTRODUÇÃO: As infecções de corrente sanguínea relacionadas com cateter (ICSRCs) apresentam impacto significativo na morbidade e na mortalidade de pacientes internados, além de elevar custos hospitalares. A utilização de equipamentos automatizados no processamento de hemoculturas gerou uma alternativa para diagnóstico de ICSRC por meio da análise da diferença de tempo de positividade (DTP) entre hemoculturas pareadas (coletadas simultaneamente) de sangue periférico e sangue de cateter. Um diagnóstico acurado e rápido dessas infecções pode otimizar as condutas clínicas e terapêuticas, poupando a retirada precoce dos cateteres. OBJETIVOS: Avaliar na rotina a DTP como ferramenta auxiliar no diagnóstico de ICSRC e determinar os principais microrganismos isolados. MÉTODOS: Foram avaliadas retrospectivamente hemoculturas coletadas no complexo do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HC/FMUSP) de maio a agosto de 2008. Somente amostras que apresentaram DTP maior que 120 minutos foram consideradas possíveis ICSRCs pelo critério laboratorial. RESULTADOS: A seção processou 11.017 hemoculturas aeróbias durante o período de estudo; somente 5% foram coletadas de forma pareada. Destas, 148 (28%) foram positivas, sendo 9% com crescimento somente em sangue periférico, 41% somente em sangue de cateter e 50% em ambas as amostras com 88% de homologia de microrganismos identificados. A DTP apresentou valores acima de 120 minutos em 50% dos casos e os microrganismos mais isolados foram Staphylococcus aureus (22%), Candida spp. (18%), Klebsiella spp. (7%) e Enterobacter spp. (7%). CONCLUSÃO: A determinação da DTP como ferramenta auxiliar no diagnóstico de ICSRC é viável e fácil de ser executada em laboratórios de rotina com automação, porém o processo de coleta das amostras pareadas deve ser rigidamente padronizado.

INTRODUCTION: Not only do catheter related bloodstream infections (CRBSIs) have considerable impact on morbidity and mortality in hospitalized patients, but they also raise hospital costs. The use of automated equipment in blood culture processing has allowed an alternative diagnosis of CRBSI by analyzing the differential time to positivity (DTP) of paired blood cultures (collected simultaneously) of peripheral blood and catheter blood. A rapid and accurate diagnosis of these infections may optimize clinical and therapeutic management, which prevents early catheter removal. OBJECTIVES: To assess DTP as an auxiliary tool for the diagnosis of CRBSI as well as to determine the main isolated microorganisms. METHODS: We evaluated blood cultures that had previously been collected in the complex Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (HC/FMUSP) from May to August 2008. According to the laboratory criteria, only DTP higher than 120 minutes was regarded as possible CRBSI. RESULTS: During the investigation period 11,017 aerobic blood cultures were processed, from which only 5% were paired samples. One hundred forty-eight (28%) samples were positive, from which 9% showed growth in peripheral blood, 41% only in catheter blood and 50% in both blood samples with 88% homology of identified microorganisms. DTP higher than 120 minutes occurred in 50% of the cases. The most common isolated microorganisms were: Staphylococcus aureus (22%), Candida spp. (18%), Klebsiella spp (7%). and Enterobacter spp (7%). CONCLUSION: The determination of the DTP as an auxiliary tool for the diagnosis of CRBSI is feasible and easily performed in clinical laboratories with automation, although the process of paired sample collection must be rigidly standardized.

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