Evaluation of PCR for direct detection of mycobacterium tuberculosis complex in sputum samples in Kampala, Uganda

Article Authors: S.P. Alarakol, J.L. Nakavuma, P. Odongo, M.L. Joloba


Objective: The aim of this study was to evaluate an in-house PCR for direct detection of Mycobacterium tuberculosis complex (MTC) in sputum samples.
Design: Across sectional study was conducted on samples isolates from suspected TB patients. Settings: Patients presenting to Mulago hospital Ward 5 TB Clinics for management and care from June 2014 to April 2015.
Subjects: Three sputum samples per patient were obtained from 30 patients with negative (N= 90) and 30 patients with positive (N= 90) ZN smear results for a total of 180 sputum samples was studied. The samples were processed using N-acetyl-L-cycteine and 4% NaOH. Genomic DNA was extracted from the sputum samples and used as template for IS6110-PCR. The prevalence of MTC bacilli in the sputum samples was determined.
Results: IS6l110-PCR detected MTC bacilli in 81% (73/90) sputum samples from patients with ZN-positive smears while it detected 51% (46/ 90) sputum samples from patients with ZN-negative. There were statistically significant associations between frequency in performing PCR on three sputum samples per patient and increased proportion of samples positive for MTC, p<0.05). All the 30 patients with ZN positive smears were positive on IS6110-PCR, while 80% (24/30) patients with ZN-negative smears were positive on IS6110-PCR. Chi square test revealed a statistically significant positive association between ZN positive and ZN-negative smears p<0.05.
Conclusion: In low income setting burden with high TB incidence and mortality, inhouse IS6110-PCR efficiently detects MTC bacilli in sputum samples and can be introduced for routine detection of these bacilli in isolates form pulmonary TB suspects.

Bibliographical metadata

Journal East African Medical Journal
Volume 95
Issue No. 4
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