Identification and genotyping of the etiological agent of tuberculous lymphadenitis in Ethiopia

Abstract

Background: In Ethiopia, little has been done to assess how Mycobacterium bovis has contributed to human tuberculosis, though the population routinely consumes unpasteurized milk and raw meat. The aim of this study was to determine the proportion of M. tuberculosis and M. bovis as etiological agents of tuberculous lymphadenitis (TBLN). Methods: Patients with lymphadenopathy (n = 171) were included in a cross-sectional study at Butajira Hospital, Southern Ethiopia. Lymph node biopsies were cultured. Patients' HIV status was identified. DNA from positive cultures was tested by PCR to identify M. bovis and M. tuberculosis. Isolates were genotyped by multiplex ligation-dependent probe amplification (MLPA) assay. Results: Among 171 patients, 156 had culture results. Of these, 107 (69%) were positive for M. tuberculosis complex (MTC). Six of the 10 HIV-positive patients were culture positive. M. tuberculosis specific sequences were identified in the DNA of each of 100 samples as assessed by RD10 targeted PCR, and each of the 95 isolates exhibited the M. tuberculosis specific TbD1 deletion by MLPA analysis. No M. bovis was identified. These results indicate that all the isolates were modern M. tuberculosis strains. Furthermore, MLPA studies confirmed that 42% of the isolates showed the Haarlem genotype and 12% displayed sequences compatible with INH resistance. No mutations conferring resistance to ethambutol or rifampicin were detected. Conclusions: Our data showed that M. tuberculosis strains had common characteristics with strains causing pulmonary TB, which appears to be the main etiological agent of TBLN.

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

“…This finding is compatible with previous studies in Ethiopia [31–33]. However, M. bovis was isolated from the two TBLN cases even though cattle owned by these patients were none reactor for CIDT test.…”

Active Tuberculosis Case Finding and Detection of Drug Resistance Among HIV-Infected Patients: A Cross-Sectional Study in a TB Endemic Area, Gondar, Northwest Ethiopia

“…This has been also evident from earlier studies conducted in other regions of Ethiopia [25,26]. This study also evaluated the association of TB occurrence with different risk factors, such as age, sex, residence area, occupation, education, marital status, alcohol intake, tobacco or shisha use, previous TB contact history, stages of HIV or ART use and CD4 count; however, none of these factors significantly correlated with the occurrence of TB (p > 0.05).…”

Tuberculosis lymphadenitis in Southwest Ethiopia: a community based cross-sectional study

“…Moreover, this might indicate that the route of acquisition of lymph node TB is probably the same as pulmonary and can partly explain why Mycobacterium bovis was not detected. Other studies have reported a predominance of Mycobacterium tuberculosis in TB lymphadenitis in Ethiopia [15,16] although bovine transmission would be expected where raw milk is consumed.…”