[Assessment of the Patho-TB kit for diagnosis of tuberculosis]

Where tuberculosis is concerned, early diagnosis, especially for active pulmonary cases, allows to quickly start therapy. We evaluated the Patho-TB kit (Anda Biologicals, France) as an alternative for the fastidious search for acid-fast bacilli by the Ziehl-Neelsen method. Three hundred and ten samples from 189 patients were collected between July 2005 and March 2006, these were divide between 301 pulmonary and 9 extrapulmonary samples. The Patho-TB tests consists of a filtration step on a cassette followed by an immuno-chromatographic revelation. Samples were decontaminated by the Kubica method; after neutralization, an aliquot of the centrifuged pellet was saparated for evaluation of the Patho-TB test. The rest was used for direct microscopic examination and cultures on solid and liquid medium. Positive results with auramine were always confirmed by the ZN staining. Analysis of the results per sample gave the follows results: 91.1% sensitivity and 85.5% specificity compared to 91.8% and 100% respectively or microscopy. Sensitivity of the Patho-TB test rose to 93.7% when only the MTB complex was considered. Per patient, the Patho-TB was found to be 96.4% sensitive and 86% specific. By comparison the sensitivity of microscopy was 94.5% and its specificity 100%. Positive and negative values were respectively 90.6% and 94.4% for the Patho-TB while they were 100% and 92.9% for microscopy. It is concluded that the Patho-TB test gives good performances; it is easy to use and very easy to determine the results. For direct observation, we recommend this test to laboratories that do not perform microscopy with auramine, which is the case in tuberculosis endemic areas.