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COMBINATION OF BLEACH AND FLOURESCENT MICROSCOPY: A MILESTONE IN THE DIAGNOSIS OF SMEAR NEGATIVE TUBERCULOSIS
Abstract
ABSTRACT
Background: The reliability of direct smear microscopy for diagnosis of tuberculosis has frequently
been questioned due to low sensitivity. Treatment of sputum with sodium hypochlorite (NaOCI)
has been used to increase sensitivity in many settings. However, no study has established the effect
of NaOCI on fl uorescent microscopy.
Objective: To establish whether NaOCI concentration method enhances positivity of fl uorescent
microscopy smear negative sputum for diagnosis of tuberculosis.
Design: A prospective study.
Setting: Mbagathi District Hospital and Centre for Respiratory Diseases Research, Kenya Medical
Research Institute.
Results: Forty fi ve (22%) specimens were culture positive. Fluorescent microscopy sensitivity
was 28.9% and 22.2% after centrifugation and sedimentation with 3.5% NaOCI, respectively (P >
0.05). Sensitivity was 24.4% and 17.8% after centrifugation and sedimentation with 5% NaOCI,
respectively (P > 0.05). Although there was no statistical signifi cance difference between the two
NaOCI concentration methods, 3.5% NaOCI with centrifugation indicated a higher yield.
Conclusion: Use of NaOCI signifi cantly enhances positivity of smear negative sputum for diagnosis
of tuberculosis when used with fl uorescent microscopy. This approach could be recommended
for screening all tuberculosis suspects especially in settings with potential smear negative
tuberculosis.
Background: The reliability of direct smear microscopy for diagnosis of tuberculosis has frequently
been questioned due to low sensitivity. Treatment of sputum with sodium hypochlorite (NaOCI)
has been used to increase sensitivity in many settings. However, no study has established the effect
of NaOCI on fl uorescent microscopy.
Objective: To establish whether NaOCI concentration method enhances positivity of fl uorescent
microscopy smear negative sputum for diagnosis of tuberculosis.
Design: A prospective study.
Setting: Mbagathi District Hospital and Centre for Respiratory Diseases Research, Kenya Medical
Research Institute.
Results: Forty fi ve (22%) specimens were culture positive. Fluorescent microscopy sensitivity
was 28.9% and 22.2% after centrifugation and sedimentation with 3.5% NaOCI, respectively (P >
0.05). Sensitivity was 24.4% and 17.8% after centrifugation and sedimentation with 5% NaOCI,
respectively (P > 0.05). Although there was no statistical signifi cance difference between the two
NaOCI concentration methods, 3.5% NaOCI with centrifugation indicated a higher yield.
Conclusion: Use of NaOCI signifi cantly enhances positivity of smear negative sputum for diagnosis
of tuberculosis when used with fl uorescent microscopy. This approach could be recommended
for screening all tuberculosis suspects especially in settings with potential smear negative
tuberculosis.
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