The bleach method improves the detection of pulmonary tuberculosis in Laos.

SETTING

Laos has a high prevalence of tuberculosis (TB) and a low prevalence of human immunodeficiency virus/acquired immune-deficiency syndrome (HIV/AIDS). Mycobacterium tuberculosis culture is not yet available. Case finding is based on the microscopic detection of acid-fast bacilli (AFB) in sputum. Liquefaction and concentration using sodium hypochlorite (bleach) could improve its yield.

OBJECTIVE

To assess the gain due to the bleach method and its feasibility in Laos, and to compare the classical method sputum processing (direct microscopy) and the bleach method for AFB detection over 3 consecutive months at a central site (Vientiane) and for 1 month at a peripheral site (Attapeu).

RESULTS

Of 1675 sputum samples collected from 612 patients, respectively 206 (12.3%) and 275 (16.4%) were AFB-positive by the direct and bleach methods (P = 0.0007), i.e., an increase in smear positivity rate of 33.5% (95%CI 31.2-35.8). The superiority of the bleach method was confirmed, regardless of the site, the aspect of the sputum and delay before analysis. This method yielded 24 more TB patients.

CONCLUSION

The bleach method, which is very easy to use, could significantly increase the yield of sputum smear microscopy for the detection of pulmonary TB in Laos.