Padronização e avaliação da acurácia do exame de baciloscopia em membrana de policarbonato após concentração pelo sistema BacFil para o diagnóstico da tuberculose pulmonar

• Autor(a) principal: Morais, Carlos Gustavo Vieira de
• Data de Publicação: 2009
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/5939
• topic: Tuberculose - Diagnóstico; Exame de escarro; Baciloscopia; Doenças Infecciosas e Parasitárias; 61

Microscopy smear is the primary method for diagnosing pulmonary tuberculosis (TB). The method is fast, inexpensive, and specific for Mycobacterium tuberculosis. However, its sensitivity is relatively low, especially in patients with paucibacillary disease which emphasizes the need for improving and/or development of new methodologies. In this context, the aim of this study was to standardize and assess the accuracy of smear microscopy using polycarbonate membranes after centrifugation of sputum samples by filtration (BacFil System) in TB diagnosis. First, we evaluated the system components and established its operating conditions. Then, to assess the system performance, a total of 450 spontaneous sputum samples from 331 patients suspected of having TB was submitted to direct smear and, after that, digested with NALC and divided into two aliquots. One aliquot was concentrated and submitted to smear microscopy and culture, while the other was treated with a solution containing sodium hypochlorite, ethanol and Triton and filtered through 13mm membranes with 0,8μm pore size in the BacFil System. After filtering, the membranes were transferred to slides, stained and a microscopic semi-quantitative analysis was done. The BacFil System showed a sensitivity of 90,8% (82,7 95,9) compared to 64,4% (53,4 74,3) and 59,5% (43,3 74,4) for the centrifugation method and direct smear, respectively. The method demonstrated a highly significant enhancement in sensitivity, operational safety, low cost and also spares the use of a centrifuge. Although BacFil is a very promising method for early diagnosis of TB, we consider it must be improved and evaluated in a multicentric study (Phase III) before its use in a laboratory routine.