Molecular Epidemiology and Comparison of Diagnostic Methods of Tuberculous Lymphadenitis, Addis Ababa, Ethiopia
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Date
2014-05
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Addis Ababa University
Abstract
Extrapulmonary tuberculosis is a significant health problem worldwide because of difficulties in its diagnosis and in monitoring its treatment, in which tuberculous lymphadenitis is high prevalent. To this effect, adequate knowledge on the species and strains of mycobacteria which circulate among the human population in specific geographic location is required.
Objective: The objective of this study was to determine the prevalence of TBLN and to compare diagnostic performance of laboratory methods in diagnosis of TBLN among clinically suspected TBLN patients; identify the dominant species/ strain of M.tuberculosis responsible for TBLN.
Materials and Methods: A cross-sectional study was conducted between February,2013 to October, 2013. Structured questionnaire, fine needle aspiration cytology and histopathology, Ziehl Nelson staining, mycobacterial culture, region of difference (RD)-PCR, spoligotyping and flowcytometry were used for undertaking this study. SPSS version 20 was used for data entry and analysis.
Result: Of the 206 TBLN suspected cases, 166 (80.6%) were positive for TBLN by FNAC and histopathological examinations. On the other hand, only 36% (74/206) were positive by mycobacterial culture. Acid-fast bacilli (AFB) were detected in 28.6% of the 133 TBLN suspected individuals while 79.3% of the 121 TBLN suspected cases were positive for mycobacteria by PCR. Majority (98.6%) of the causative agent of TBLN was M.tuberculosis. Further characterization of 74 isolates to strain level by spoligotyping, 57 isolates were classified into one of the 26 shared international types (SITs) according to SpolDB4.0 and the remaining 16 isolates generated 13 different spoligotype patterns which had not been reported to the SpolDB4.0.The most prevalent strains of M. tuberculosis isolated in this study were SIT149, SIT53, SIT26 and SIT37 comprising 52.6% of the total strains. The strains were further classified into families in which the most prevalent were T, CAS and Haarlem comprising of 81.1% of the isolates. Classification of the strains into lineages leads to indicated modern lineage was the most prevalent comprising 66.2%.
Conclusion: In this study it has been shown that, several clusters and new strains of M. tuberculosis circulate in TBLN patients in Ethiopia. As mapping the population structure of M. tuberculosis is vital to understand the transmission and disease dynamics of TB and set appropriate control measure. XII
Key Words: Tuberculosis lymphadenitis, MTC, RD9 and RD4 Typing, Spoligotyping, Mycobacterium family, Mycobacterium lineage, Phenotyping and Addis Ababa
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Keywords
Tuberculosis lymphadenitis, MTC, RD9, RD4 Typing, Spoligotyping