The objective of this study was to assess the number of sputum specimens
necessary for a reliable diagnosis of pulmonary tuberculosis (PTB) in a
pastoralist population in Ethiopia.
Using routine data from Ethiopia, where three sputum specimens are
currently recommended for the diagnosis of PTB, the study documented,
(i) the proportion of persons with suspected, PTB who submitted a first,
second and third sputum specimen for smear examination and (ii) the
incremental smear-positive yield from the first, to the second and third
Of 505 persons with suspected PTB, 107 (22%) failed to submit three
samples. Of 60 patients who submitted three sputum samples with at least
one smear-positive sample, the first sputum sample was smear positive in
56 (93%) cases; the second sputum sample was the first to be positive in
3 (5%) cases and in only one case was the third sample the first to be
smear positive (additional yield 2%).
The study concluded that in a pastoralist setting, a reliable diagnosis
of PTB can be achieved with two sputum specimens and PTB diagnosis may
be adequate with just one sputum specimen. However, if this more radical
approach was adopted, ways of increasing diagnostic sensitivity should
Khogali, M.; Tayler-Smith, K.; Zachariah, R.; Gbane, M.; Zimble, S.; Weyeyso, T.; Harries, AD. Diagnosis of pulmonary tuberculosis in a pastoralist population in Ethiopia: are three sputum specimens needed? Tropical Medicine and International Health (2013) 18 (5) 632-635. [DOI: 10.1111/tmi.12082]
Diagnosis of pulmonary tuberculosis in a pastoralist population in Ethiopia: are three sputum specimens necessary?