Improved sputum microscopy for a more sensitive diagnosis of pulmonary tuberculosis

Diagnosis of tuberculosis in low-income countries is hindered by the low sensitivity of direct sputum smear microscopy. We compared an improved method based on liquefaction of sputum with NaOCl followed by centrifugation with standard direct smear in a central hospital and at peripheral health centres in Honduras. Specificity was high and sensitivity significantly better with the NaOCl method. Moreover, this technique is safe, inexpensive and easy to perform. We recommend its implementation to enable rapid, sensitive laboratory diagnosis of pulmonary tuberculosis, especially in resource-poor settings where culture is not possible.