ABSTRACT
Multidrug-resistant tuberculosis (MDR-TB) has emerged as a major public health problem. Drug-resistance surveillance data show that 3.9% of new and 21% of previously treated TB cases were estimated to have had rifampicin/ multidrug-resistant tuberculosis (MDR/RR-TB) in 2015. This implies that the MDR-TB is increasing alarmingly. Hence, a better understanding of drug resistance mechanisms and genotypes associated with multidrug resistance in M. tuberculosis is crucial for improving diagnostic and therapeutic methods to treat individuals with MDR-TB. The aim of this study was to analyze molecular drug resistance mutations of MDR-TB isolates from the cases of TB-lymphadenitis in relation to its genetic lineages. A cross-sectional study was conducted on culture positive cases from July to October, 2014 in Addis Ababa, Ethiopia. Sixty isolates were included to analyze drug resistance mutated gene responsible for MDR-TB in relation to its molecular genotyping. Mycobacterial culture, GenoTypeMTBDR plus and Spoligotyping were used to undertake the study. Of 60 TBLN isolates, 8.3% were identified MDR-TB cases and one isolate was isoniazid mono-resistant. Eleven isolates in T3-ETH genetic sub lineage were sensitive to both RMP and INH, while only 2 isolates were MDR-TB. Most of the RMP- resistant isolates showed mutation in codon S531L and all isolates mutated in the katG gene conferring INH resistant strains had mutations in codon of S315T1. Screening for the rpoB and katG gene mutation of tuberculosis lymphadenitis is useful in Ethiopia for an early detection and treatment of MDR-TB. Besides, there is a drug resistance variation among different lineages of Tuberculosis lymphadenitis which has important consequences for the development of efficient control strategies.
ABSTRACT
BACKGROUND: In Ethiopia, one of the world's 22 high tuberculosis (TB) burden countries, one third of the tuberculosis (TB) cases are attributed to tuberculosis lymphadenitis (TBLN). However, information on the molecular type of the mycobacterial species and strains that cause TBLN in the country is scarce. OBJECTIVE: To identify the species and strains of mycobacteria that cause TBLN in Ethiopia. METHODS AND RESULTS: A cross-sectional study was conducted among 206 presumed TBLN cases to characterise positive culture isolates. Mycobacterium tuberculosis complex species and strains were identified using region of difference 9 deletion and SITVIT WEB, respectively. Of the 206 fine-needle aspirate samples collected, 74 (36%) were culture-positive: 73 (98.6%) of the isolates were M. tuberculosis, and the remaining 1.4% were M. bovis. Further characterisation of the 73 M. tuberculosis isolates led to 26 distinct spoligotype international types (SITs) and 13 newly identified patterns. The most prevalent strains were SIT149, SIT53, SIT26 and SIT37 of sublineages T3-ETH, T1, CASI-DELHI and T3, respectively; these accounted for 52.6% of the total number of strains. CONCLUSION: TBLN was mainly caused by M. tuberculosis and highly clustered strains SIT149, SIT53, SIT26 and SIT37 of sublineages T3-ETH, T1, CASI-DELHI and T3, respectively.
