Molecular Characterization of Mycobacterium tuberculosis Complex Isolated from Tuberculous Lymphadenitis Patients at Dessie Private Hospitals, Northern Ethiopia

Abstract

Background: Tuberculosis (TB) is an infectious disease that has major global public health problem. Tuberculous lymphadenitis is among the most common presentations of extra pulmonary tuberculous in developing countries. Although the incidence of Tuberculous Lymphadenitis (TBLN) is rising in different regions of Ethiopia, the incriminated mycobacterium species and strains have been rarely characterized. The present research was aimed to characterize Mycobacterium tuberculosis Complex (MTC) and asses associated risk factors.Methods: A cross sectional study was conducted from September 2012 up to April 2013 on 90 tuberculous lymphadenitis suspected patients who were visited Dessie Private Hospitals during the study period. Clinical, cytological, Culture, deletion typing and spoligotyping, and interviewer administered questionnaire was used to collect associated risk factors. Data were cleaned, coded and fed into SPSS version 20.0 for analysis in this study. Results: Out of 90 fine needle aspirate samples, 33% (32/90) of them were culture positive. Based on the deletion typing of the 32 isolates using region of difference-9 (RD9) showed that all of the isolates were Mycobacterium tuberculosis. Further characterization of the 32 isolates using spoligotyping lead to the identification of 28 different strains. Two of these strains consisted of three isolates each while the remaining 26 strains were orphan that consist a single isolate each. Comparison of the 28 patterns with the patterns in the international spoligotype database, SpolDB4 showed that 17 patterns were new spoligotypes. The occurrence of the disease was not associated with age, sex, marital status, occupation, education, previous contacts with TB patients, consumption of raw milk and Bacille Calmette Guerin vaccination (p>0.05). However, resident area, previous history of treatment with anti-TB drugs and involved lymph nodes were significantly associated with the occurrence of TBLN (p<0.05). Conclusion: this study has shown that 93% of the isolates were orphan which could suggest less frequent transmission of the disease in the study area. Thus, further study on the molecular Epidemiology of the disease should be needed.

Keywords: Dessie Private Hospitals Molecular typing, Northern Ethiopia, Tuberculous lymph adenitis