Drug sensitivity of clinical isolates of Mycobacterium tuberculosis and its association with bacterial genotype in the Somali region, Eastern Ethiopia

Abstract

BackgroundDrug resistance is becoming a major bottleneck for tuberculosis (TB) control programs in countries with high TB burdens. Although several studies were conducted on the drug sensitivity of Mycobacterium tuberculosis (M. tuberculosis) in central Ethiopia, there is a lack of data on the drug sensitivity of M. tuberculosis in the peripheral regions of the country including in the Somali region. Therefore, the objective of this study was to evaluate the drug sensitivity of M. tuberculosis and its association with bacterial genotype and evaluate the performance of Xpert MTB/RIF (Xpert) in detecting resistance to rifampicin (RIF).MethodsA total of 302 M. tuberculosis were tested using the BD BACTEC-Mycobacteria Growth Indicator Tube 960 (MGIT 960) system for their drug sensitivity to the first-line anti-TB drugs. Besides, the drug sensitivity of 10 multidrug-resistant (MDR) M. tuberculosis isolates was evaluated for the second-line anti-TB drugs. Additionally, 177 of the 302 isolates were tested for genotypic drug resistance using Xpert. Chi-square and Fisher's exact tests were used for the evaluation of the association between variables and drug sensitivity.ResultsThe overall prevalence of resistance to at least one drug was 11.6% (95% CI: 7.9–15.2%), while the prevalence of MDR was 3.3% (95% CI: 1.3–5.3%). Two of the 10 MDR isolates were resistant to capreomycin. The spoligotype Shared International Type (SIT) 149 was significantly associated with either monoresistance or MDR (p < 0.05). Of the 177 isolates tested by Xpert, 6.2% (11/177) were RIF-resistant. Discordant between Xpert and MGIT 960 was observed in one isolate and linked with probe-binding delay (ΔCT max = 5.8). The sensitivity and specificity of the Xpert assay were 100 and 99.4%, respectively, while its positive and negative predictive values were 90.9 and 100%, respectively.ConclusionThe magnitude of MDR M. tuberculosis in the Somali region of Ethiopia was higher than the national prevalence of MDR-TB warranting the strengthening of the TB control program in the Somali region. Besides, drug resistance was associated with SIT 149 spoligotype (genotype). The Xpert assay was observed to have high sensitivity and specificity in detecting RIF-resistant M. tuberculosis, which is encouraging for its application widely.

Epidemiology of first-and second-line anti-tuberculosis drug resistance in new pulmonary tuberculosis cases in Addis Ababa metropolitan area, Ethiopia

“…The findings of this study demonstrated that all MDR-TB isolates were susceptible to all recently recommended second-line anti-TB drugs tested and none of these isolates were found to be Pre-XDR or XDR-TB. Compared to this finding, similar results were reported in previous studies conducted by Tessema B et al, (2012) [28], and Worku G et al, (2022) [31] in Ethiopia. However, a significant proportion (81.8%) of isolates exhibited resistance to Ethionamide in this study.…”

“…In this study, we identified a rate of 14.1% (22/156) resistance of M. tuberculosis strains to at least one first-line anti-TB drug, while 85.9% (134/156) were found to be pan-susceptible M. tuberculosis strains in new presumptive pulmonary TB cases. Similar to this finding, a comparable rate of resistance of M. tuberculosis strains to at least one first-line anti-TB drug among new cases was reported by Tessema B et al, (15.8%, 2012) [28], Adane K et al, (15.58%, 2015) [29], Lobie TA et al, (16.1%, 2020) [30], Worku G et al, (11.6%, 2022) [31] in Ethiopia; Doss M et al, (13.4%, 1999) [32] in Côte d'Ivoire; Antunes ML et al, (17.8%, 2000) [33] in Portugal; Glasauer S et al, (12.7%, 2019) [34] in Germany and Ullah I et al, (11.5%, 2016) [35] in Pakistan.…”

“…The absence of monoresistance against RIF and EMB was reported in the previous studies by Agonafir M et al, (2010) [53], Tessema B et al, (2012) [28], and Worku G et al, (2022) [31] in Ethiopia. A higher rate of sensitivity to RIF alone may be a good indicator of the success of the DOTs program in the study area in Ethiopia.…”

Molecular typing and drug sensitivity profiles of M. Tuberculosis isolated from refugees residing in Ethiopia

“…There was neither pre-XDR-TB nor XDR-TB detected in the current study and a similar result was reported by a study [28] from the Somali region of Ethiopia where no pre-XDR/XDR-TB was reported. In support of these, a lower prevalence of pre-XDR-TB and no XDR-TB report [29] detected from Ethiopian national routine laboratory-based DR surveillance.…”

Multidrug-resistant tuberculosis: latest opinions on epidemiology, rapid diagnosis and management

“…Only primary quantitative studies were selected from the search output. The title of the study, year of study, study setting, study design, MDR-TB confirmed number of cases, MDR-TB/HIV co-infection proportion, and the outcome explored were characteristics retrieved from the studies (Table 1) [9–13,14 ▪▪ ,15–21,22 ▪▪ ,23,24 ▪▪ ,25–29,30 ▪ ,31 ▪ ,32–36,37 ▪▪ ,38–48,49 ▪▪ ,50 ▪ ].…”