Genetic Diversity ofMycobacterium tuberculosisComplex Isolated from Tuberculosis Patients in Bahir Dar City and Its Surroundings, Northwest Ethiopia

Abstract

The knowledge of the diversity of strains of Mycobacterium tuberculosis complex (MTBC) species in a specific geographical region can contribute to the control of tuberculosis (TB). This study was conducted to identify the MTBC isolates to the species and spoligotype international type (SIT) level by spoligotyping. A total of 168 MTBC isolates were recovered from TB patients, spoligotyped, and their patterns were compared with those of the strains registered in the SITVIT2 database. Of 168 isolates spoligotyped, 89 patterns were identified. Ninety-eight isolates were clustered into 19 strain groups with clustering percentage of 58.3%. Forty-four strains matched the preexisting SITs in the SITVIT2 database. The dominant strains were SIT289, SIT134, and SIT3411, comprising 16.7% (28/168), 7.14% (12/168), and 4.76% (8/168) of the isolates, respectively. Euro-American (51.2%), East-African-Indian (34.5%), and M. africanum (9.52%) were the major lineages identified. Two strains of M. bovis were isolated from TB lymphadenitis cases. The high percentage of clustered strains of M. tuberculosis could suggest that a small number of lineages of M. tuberculosis are causing the disease in the area while isolation of M. bovis could suggest its zoonotic potential. Additionally, identification of M. africanum requires further confirmation by tools with a better discriminatory power.

Preliminary investigation of the transmission of tuberculosis between farmers and their cattle in smallholder farms in northwestern Ethiopia: a cross-sectional study

“…Similar findings were reported from previous Ethiopian studies [9, 19, 20]. These studies isolated M. bovis from human pulmonary TB (PTB, it is an infectious disease principally caused by M. tuberculosis , which is primarily a human pathogen and characterized by the growth of tubercles in the tissues, especially the lungs) and/or TBLN cases, and suggested the occurrence of transmission of zoonotic TB between livestock and humans.…”

“…Bacterial colonies from culture-positive samples were Ziehl-Neelsen stained to identify acid fast bacilli (AFB). Cultures positive for AFB were inactivated by heating at 85 °C for 45 min in a water bath and spoligotyped as previously described [20]. …”

“…In Ethiopia, the presence of BTB in cattle [9–18] and human due to M. bovis [9, 19, 20] were reported previously. After isolating M. tuberculosis from animals it was also suggested the presence of human to animal transmission in Ethiopia [21–23].…”

Genetic diversity and drug resistance pattern of Mycobacterium tuberculosis strains isolated from pulmonary tuberculosis patients in the Benishangul Gumuz region and its surroundings, Northwest Ethiopia

“…The SIT289 strain was previously reported as predominant in Gambella and Bahir Dar. Both regions share long borders with the current study area in the southwest and northwest parts of the country, respectively [31,32]. SIT53 is frequent in central (Ambo), north (Bahir Dar, Dessie), and south Ethiopia (Dilla) [32,33].…”

“…Both regions share long borders with the current study area in the southwest and northwest parts of the country, respectively [31,32]. SIT53 is frequent in central (Ambo), north (Bahir Dar, Dessie), and south Ethiopia (Dilla) [32,33]. This study site has, despite its relative isolation, an increasingly mixed population, including people originating from different parts of the country resettled in the 1980s [34], which could contribute to the diversity in the pool of circulating mycobacterial strains.…”