Utility of nucleic acid amplification techniques for the diagnosis of pulmonary tuberculosis in sub-Saharan Africa.
METHODS
Lusaka, Zambia.


OBJECTIVE
To investigate the utility of nucleic amplification tests for the diagnosis of pulmonary tuberculosis in a resource-poor setting with a high incidence of human immunodeficiency virus (HIV).


METHODS
Sputum specimens from suspects attending a referral chest clinic were examined by low-cost 'in-house' one-tube nested polymerase chain reaction (PCR), the enhanced Gen-Probe Amplified Mycobacterium Direct Test (AMTD), auramine smear and Lowenstein-Jensen culture.


RESULTS
PCR and AMTD detected respectively 80% and 92% of smear-positive specimens and 40% and 60% of smear-negative, culture-positive specimens. AMTD was positive for 18 culture-negative suspects; subsequent investigation indicated these to be six confirmed tuberculosis patients, nine judged from radiological data and clinical follow-up studies to have pulmonary tuberculosis, and three non-tuberculosis patients. Sensitivity for smear, culture, PCR and AMTD, when compared to a gold standard incorporating both microbiological and clinical data, was respectively 29%, 69%, 55% and 81%.


CONCLUSIONS
In this setting, the sensitivity of the low-cost PCR proved insufficient for its effective use as a tool for diagnosing pulmonary tuberculosis, while AMTD performed considerably better than the current laboratory methods for diagnosis of pulmonary tuberculosis. However, the high cost of this technology may limit its application in the public sector of low-income countries.
Kambashi
B
B
ZAMBART Project, Department of Medicine, University Teaching Hospital, Lusaka, Zambia.
Mbulo
G
G
McNerney
R
R
Tembwe
R
R
Kambashi
A
A
Tihon
V
V
Godfrey-Faussett
P
P
D017088:AIDS-Related Opportunistic Infections / Q000175:diagnosis* / Q000453:epidemiology*; D000328:Adult; D001483:Base Sequence; D003906:Developing Countries; D005260:Female; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D021141:Nucleic Acid Amplification Techniques / Q000379:methods / Q000706:statistics & numerical data*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000453:epidemiology*; D015024:Zambia / Q000453:epidemiology