The bleach method improves the detection of pulmonary tuberculosis in Laos

Area of Science:

• Medical Microbiology
• Public Health
• Infectious Diseases

Background:

• Laos faces a high burden of tuberculosis (TB) with limited diagnostic capabilities.
• Current TB case finding relies on sputum microscopy for acid-fast bacilli (AFB), which has suboptimal sensitivity.
• Mycobacterium tuberculosis culture is not widely available in Laos.

Purpose of the Study:

• To evaluate the effectiveness and feasibility of the bleach method for AFB detection in sputum.
• To compare the diagnostic yield of the bleach method against direct microscopy for pulmonary TB diagnosis in Laos.

Main Methods:

• A comparative study was conducted at central and peripheral sites in Laos.
• Sputum samples were processed using both direct microscopy and the bleach liquefaction-concentration method.
• AFB detection was performed via microscopy on processed sputum samples.

Main Results:

• The bleach method increased smear positivity by 33.5% compared to direct microscopy (16.4% vs 12.3%).
• This improvement was consistent across different sites and sputum sample characteristics.
• An additional 24 pulmonary TB patients were identified using the bleach method.

Conclusions:

• The bleach method offers a significant increase in the detection rate of pulmonary TB via sputum smear microscopy.
• Its ease of use makes it a feasible and valuable tool for enhancing TB diagnosis in resource-limited settings like Laos.