Evaluation of AFB smear, culture, real-time PCR methods for detection of tuberculosis

Background: Tuberculosis is the leading cause of mortality worldwide and kill 3 million people every year. It is caused by members of theMycobacterium tuberculosis complex (MTC). Zambia is ranked among the world’s top 10 high incident countries. Lack of routine mulecular characterization of mycobacteria in patients presenting with pulmonary tuberculosis in the country’s health facilities including Ndola Central Hospital has led to non availablity of data on specific species other thanM. tuberculosis that are in circulation. This information is vital for proper patient management, as different species and strains of mycobacteria have varying sensitivies to drugs, pathogenesis as well as their epidemiology. The study was aimed at characterizingmembers of theMTC in patients presenting with pulmonary tuberculosis at Ndola Central Hospital in Zambia from February 2012 to August 2012. Methods & Materials: This was a cross-sectional study targeting symptomatic and clinically suspected pulmonary TB patients attending Ndola Central Hospital. A total of 197 consenting adult patiets were included in the study, from whom a structured questionnaire probing their socioeconomic, HIV status and possible source of the disease status. Additionally, 2 sputum samples were collected fromwhere Microscopy, culture, spoligotyping and deletion analysis were carried out. Results:About 60%of theparticipantsweremale. The total positivity rate on culturewas 65% (N=138). Out of seventy-one samples analysed for IS6110 deletion analysis, 41 sampleswhere confirmed to beM. tuberculosis since theywere positive for RD1, RD4, RD9 and RD12. Four samples were confirmed to be M. canettii as characterized by the absence of RD12 amplification. Among the six clusters obtained by spoligotyping, the SAF1 family was largest comprising 43.5% of the isolates. The study also found four orphan strains which did not match with previously identified strains. Conclusion:Other thanM. tuberculosis,Mcanettii has also been implicated in Tuberculosis infection in Ndola.