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PubMed2025

Whole genome sequencing-based detection of extensively drug-resistant tuberculosis from Ethiopia.

BACKGROUND: Rapid and accurate detection of extensively drug-resistant tuberculosis is crucial for effective intervention. Next-generation sequencing technologies have been recommended to rapidly and accurately detect resistance to second-line anti-TB drugs. We deployed whole-genome sequencing to detect mutations associated with drug resistance in pre-extensively drug-resistant tuberculosis and extensively drug-resistant tuberculosis strains in Ethiopia. METHODS: This report is part of the routine laboratory-based drug-resistance surveillance in Ethiopia. Among 15 pre-extensively drug-resistant tuberculosis and extensively drug-resistant tuberculosis isolates identified during the study period, eleven isolates were retrieved by Whole-genome sequencing. Illumina NextSeq 550 instruments were used to generate genomic data. Lineage and drug-resistance prediction were performed with Tuberculosis Profiler, while phylogeny was conducted by IQ-tree. RESULTS: Of the genotyped isolates, whole-genome sequencing identifies five extensively drug-resistant tuberculosis and four pre-extensively drug-resistant tuberculosis strains. It detects fluoroquinolone resistance mutations gyrA (Ala90Val, Asp94Tyr, Asp94Gly). Bedaquiline resistance mutations are found in atpE (Glu61Asp) and Rv0678 (139dupG, 141 and 142dupTC). Cross-resistance is identified between bedaquiline and clofazimine (n = 4) and delamanid and pretomanid (n = 1). Concordance result is observed between phenotypic drug-susceptibility testing and whole-genome sequencing for eight cases, while three cases are discordant (fluoroquinolones, delamanid, and pretomanid). Phylogenetic analysis reveals three major lineages: Lineage 4 (Euro-American, n = 6 isolates), Lineage 3 (East African-Indian, n = 3 isolates), and Lineage 1 (Indo-Oceanic, n = 2 isolates). CONCLUSIONS: Whole-genome sequencing identifies dominant mutations in genes such as gyrA, atpE, and Rv067 that are associated with resistance to second-line anti-tuberculosis drugs. Significant cross-resistance is observed between key second-line drugs, bedaquiline and clofazimine, as well as delamanid and pretomanid. This finding highlights the need for routine genomic surveillance to detect drug resistance early, improve treatment outcomes, and prevent transmission.

Journal Article↗

PubMed2026

MIC-based tuberculosis drug susceptibility testing using Sensititre MYCOTB: a diagnostic accuracy meta-analysis.

Accurate drug susceptibility testing (DST) is crucial for designing effective regimens for multidrug-resistant (MDR) and pre-extensively drug-resistant tuberculosis (pre-XDR TB). Sensititre MYCOTB enables simultaneous determination of minimum inhibitory concentrations (MICs) for multiple drugs, but its diagnostic performance varies across studies. This meta-analysis evaluated the diagnostic performance of Sensititre MYCOTB for key MDR and pre-XDR TB drugs. The protocol was registered in PROSPERO (CRD420251230599). PubMed, Cochrane, Google Scholar, Scopus, ONOS, Web of Science, ScienceDirect, and registries were systematically searched for studies published between 2010 and 2025. Studies comparing the Sensititre MYCOTB with reference DST for Mycobacterium tuberculosis complex (MTBC) were included. Bias assessment and pooled diagnostic accuracy estimates were generated. Fourteen studies, including 1,728 isolates, were analyzed. Rifampicin and isoniazid demonstrated high sensitivity (0.976 [95% CI: 0.94-0.99] and 0.977 [95% CI: 0.95-0.99]) and specificity (0.958 [95% CI: 0.84-0.98] and 0.957 [95% CI: 0.83-0.99], respectively) with low heterogeneity. Amikacin, kanamycin, and ofloxacin demonstrate good diagnostic accuracy, with high specificity (>0.98 [95% CI]). Moderate diagnostic accuracy was observed for ethambutol, streptomycin, ethionamide, and rifabutin. Cycloserine, moxifloxacin, and para-aminosalicylic acid showed inconsistent performance despite excellent specificity (>0.97 [95% CI]). Sensitivity analysis partially improved pooled sensitivity for moxifloxacin 0.801 (95% CI: 0.585-0.924) and para-aminosalicylic acid 0.76 (95% CI: 0.518-0.894), whereas cycloserine remained at 0.436 (95% CI: 0.190-0.725), although heterogeneity persisted. Sensititre MYCOTB DST demonstrates high diagnostic accuracy for MDR-TB and pre-XDR-TB drugs, while caution is required with cycloserine, moxifloxacin, and para-aminosalicylic acid. These findings support the integration of MIC-based testing into clinical decision-making.

Microbial Sensitivity Tests↗

PubMed2025

Emergence of extensively and pan-drug resistance in clinical bacterial isolates: A systematic scoping review from Ethiopian public health perspective.

INTRODUCTION: The growing challenge of antimicrobial resistance in Ethiopia and itsprogression towards XDR and PDR has become a critical public health concern. Therefore, thisreview determined the current state of emerging XDR and PDR bacteria, including pre-XDR and XDR-TB, their contributing factors, advancements, and future perspectives against drug-resistant bacteria, as well as their implications for public health and insights for future research. METHODOLOGY: This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) guidelines. A systematic search of all available literature was conducted using PubMed/Medline, Scopus, EMBASE, Google Scholar, Hinari, Web of Science, ScienceDirect, Cochrane Library, and African Journals Online databases.This study included original articles published in English that reported XDR and PDR bacteria, Pre-XDR-TB, and XDR-TBb without limit on the study period and publication year. Descriptive statistics were used to summarize the findings. RESULTS: Twenty-five studies published between 2010 and 2025 were included in this review. Among 5620 bacterial isolates identified,1289 were XDR (22.9%), with the prevalence ranging from 5.7% to 43.2%. A total of 440 bacterial isolates were PDR (9.1%), with its prevalence in individual studies ranged from 0.8% to 19.1%. The most common XDR bacteria identified were Klebsiella species; 26.7% (2.8%-84.6%), followed by E. coli; 26.4%(14.6%-35.7%), Acinetobacter species; 24.9%(10.1%-58.3%), and P. aeruginosa; 18.7% (2.8%-44.4%). The most frequently identified PDR bacteria were Acinetobacter species; 17.3% (7.9%-50.0%), followed by Klebsiella species; 13.7%(2.7%-25.8%), E. coli; 10.2%(2.4%-22.6%), and P. aeruginosa; 5.7%(4.3%-33.3%). Additionally, from 1419 MDR-TB and 160 TB confirmed cases, Pre-XDR-TB was 3.4% (2.4%-5.7%) and XDR-TB was 1.5%(0.6%-10.0%). These isolates were identified from different clinical specimens, which represents a significant concern in community and hospital settings. CONCLUSION: The emergence of XDR and PDR represents a major threat to Ethiopian public health, resulting in increased morbidity, mortality, prolonged hospitalizations, high healthcare costs, and challenged treatment options. Urgent national surveillance and genomic detection of resistance mechanisms are needed to better track the spread of drug-resistant bacteria, promote antimicrobial stewardship, and enhance drug and vaccine trials.

Ethiopia↗

PubMed1979

Tuberculosis in Oriental immigrants: a study in military dependents.

Tuberculosis in Oriental immigrants is likely to be resistant to therapy with certain drugs. In 73 military dependents with positive cultures for tuberculosis who immigrated from six Asian countries, the tuberculosis was found to be resistant to isoniazid in 58 percent (42 patients), to streptomycin in 36 percent (26 patients), to p-amino-salicylic acid in 14 percent (ten patients), to rifampin in 7 percent (five patients), and to ethambutol in 7 percent (five patients). Despite the presence of drug-resistant organisms and often extensive disease, negative cultures were attained in all but one patient. Consideration of the high incidence of drug-resistant tuberculosis should be made in planning a program of treatment for these patients. Recognition of cultural differences may also be of value in the successful treatment of this difficult group of patients.

Adolescent↗

PubMed2026

Comparative in vitro antimicrobial susceptibility profiles of clofazimine and pyrifazimine against clinical isolates of Mycobacterium tuberculosis in southwest China.

UNLABELLED: Clofazimine (CFZ) is a key drug used to treat drug-resistant tuberculosis (DR-TB), while pyrifazimine (TBI-166) is an improved riminophenazine derivative with better pharmacokinetics. However, there is a lack of data on its susceptibility and resistance in regions with a high disease burden, such as southwestern China. We compared the in vitro antimicrobial activities of CFZ and TBI-166 against 249 DR-TB clinical isolates (99 multidrug-resistant TB [MDR-TB] and 150 pre-extensively drug-resistant TB [pre-XDR-TB] isolates) from southwestern China. TBI-166 exhibited a concentration-dependent biphasic antimicrobial pattern compared to CFZ. TBI-166 showed significantly greater potency at low concentrations (MIC₅₀ = 0.031 µg/mL TBI-166 vs 0.25 µg/mL for CFZ; P < 0.001), but attenuated inhibition at high concentrations (MIC₉₀ > 4 µg/mL vs 1 µg/mL for CFZ; P < 0.001). However, at high concentrations, the antibacterial effect of TBI-166 is weaker than that of CFZ (40% of TBI-166-resistant isolates have MIC > 4 µg/mL, compared to 6.67% of CFZ-resistant isolates, P < 0.001). Epidemiological cutoff values (ECOFFs) were 1.0 µg/mL for CFZ and 0.25 µg/mL for TBI-166. Based on these in vitro ECOFFs, the resistance rate to TBI-166 (20.1%, 50/249) was significantly higher than that to CFZ (6.0%, 15/249, P < 0.0001). Whole-genome sequencing revealed that mutations in Rv0678 were prevalent in dual-resistant isolates (10/14) and TBI-166 monoresistant isolates (5/40), while Rv1979c mutations were less frequent, and no pepQ mutations were detected. These mutations differed from known hotspots, suggesting potential novel resistance mechanisms. IMPORTANCE: Drug-resistant tuberculosis (DR-TB) remains a major global health challenge, and optimizing treatments for high-burden regions like southwest China is crucial. This study is the first to detail the differential in vitro activities of clofazimine (CFZ) and the novel TBI-166 against clinical DR-TB isolates from southwest China, alongside their resistance-associated genetic profiles. Findings show TBI-166 has enhanced low-concentration potency but higher resistance rates, plus novel mutations in Rv0678 and Rv1979c linked to resistance. These insights will help refine clinical regimens for DR-TB and strengthen regional resistance surveillance, both of which are essential for controlling the spread of DR-TB in southwest China and informing treatment and surveillance strategies in other similar high-burden areas globally.

Clofazimine↗

PubMed2026

Genomic insights into low-level rifampicin resistance mediated by borderline rpoB mutations in Mycobacterium tuberculosis: prevalence and phylogeny in Northeast China.

The emergence of low-level rifampicin (RIF) resistance in Mycobacterium tuberculosis poses a challenge to tuberculosis (TB) control, as it often leads to discordance between genotypic resistance detected by molecular assays (e.g., Xpert MTB/RIF) and phenotypic susceptibility in conventional drug susceptibility testing (DST). In this study, we performed whole-genome sequencing (WGS) on 17 clinical isolates from Changchun, Northeast China, which exhibited such discordance. All isolates harbored functional borderline mutations in the rpoB RRDR region, predominantly Leu452Pro and Leu430Pro (29% each), followed by His445Asn (18%). RIF minimum inhibitory concentration (MIC) values ranged from ≤0.25 to 1.0 mg/L, confirming low-level resistance. Notably, 53% (9/17) of the isolates were co-resistant to fluoroquinolones and 24% (4/17) to isoniazid (INH). According to WHO classification, 59% (10/17) were pre-extensively drug-resistant TB (Pre-XDR-TB) or multidrug-resistant TB (MDR-TB). Phylogenetic analysis revealed that 94% (16/17) belonged to the East Asian Beijing lineage (Lineage 2.2.1), with no evidence of recent local transmission. These findings underscore the complexity of low-level RIF resistance and its frequent association with broader drug resistance in a dominant lineage, highlighting the need for integrating MIC and WGS into diagnostic algorithms to guide appropriate treatment and surveillance.IMPORTANCEThe accurate detection of RIF resistance is critical for the management of TB, yet standard phenotypic methods often fail to identify strains with low-level resistance conferred by borderline rpoB mutations. This study provides the first genomic characterization of such discordant isolates in Northeast China, revealing a high prevalence of co-resistance to other key drugs and a strong association with the locally dominant Beijing lineage. The findings emphasize that reliance on phenotypic DST alone may lead to underestimation of drug resistance and inappropriate treatment, potentially contributing to the emergence and spread of Pre-XDR-TB and MDR-TB. Incorporating MIC determination and WGS into routine diagnostics could enhance detection, inform tailored therapy, and improve surveillance of these clinically significant strains.

Mycobacterium tuberculosis↗