Improved microscopy diagnosis of pulmonary teberculosis using sodium hypochlorite concentration technique in Tanga, Tanzania

Abstract

Pulmonary tuberculosis diagnosis commonly relies on the bacteriological examination of sputum. A cross-sectional hospital-based study was carried out to compare on "on the spot" sputum staining using sodium hypochlorite (bleach method) and routine Ziel-Neelsen (ZN) staining technique. Study candidates included individual patients presenting with cough <3 weeks (Group I) and > or =3 weeks (Group II). Sensitivity and specificity of the bleach method was calculated and compared at 100% using the ZN staining technique as the standard. A total of 171 patients (94 males, 77 females) with mean age 34.9 years (SD +/- 12.9) were recruited. Fifty-eight patients had coughed for <3 weeks while 113 had coughed for 23 weeks. Smear-positive TB in Group I was 13.8% (95% CI = 5-23) while in Group II was 25.7% (95% CI = 21-29). Using the bleach method, the prevalence of smear-positive TB in Group II was 28.3% (CI 95% = 20-36). This was an increase in smear-positivity rate of 15.6% as compared to the ZN technique. These results suggest that the use of bleach technique "on the spot" improve the sensitivity of tuberculosis diagnosis among patients with a history of coughing of over three weeks. However, further studies in different settings are recommended to validate the technique.