Pulmonary Tuberculosis [PTB] Case Detection Rate Using Smears Made From Sputa; Directly, After Concentration and Culture Isolation for Afb

Abstract

Three hundred and eighty-one patients with High Risk Bronchopulmonary Symptoms [HRBS] who presented at Yaba and Lagos University Teaching Hospital [LUTH] chest clinics were screened for Acid Fast Bacilli [AFB] comparatively, using Zhiel Nielson [ZN] staining method with Direct Smear [DS], Concentrated Smear [CS] and Concentrated deposit culture isolates on Lowenstein Jensen [LJ] medium, between April, 2000 to May, 2002. The prevalence rates of 24.4%, 36.2% and 49.6% were recorded respectively. The culture method were shown to correlate well with both DS [94.7%] and CS [98.8%] for positive samples; thus, demonstrating high specificity of the methods. Contamination rate of 6% were recorded during the culture procedure. Eighty-one percent of all positive samples were from both “on-the-spot” and “early morning” samples, while early morning samples alone made an additional 16 [19%] positive samples. The age specific incidence rate of positive subjects yielded more bacilli count [47%] of +++ [i.e. more than 10 acid fast bacilli per field in at least 20 fields], when compared with the direct smears with only 6.5% of +++. Apart from demonstrating the superiority of concentrated smears over the direct smears for AFB rapid and cheap screening, we equally confirmed the usefulness of good, adequate and properly timed sputum samples collection for improved TB case detection in a resource poor setting. Digested sputum procedure is therefore, recommended for routine use in out TB diagnostic centers as minimal training is only required.

NQJHM Vol. 14 (1) 2004: pp. 8-10