Molecular epidemiology of the RDRio genotype of Mycobacterium tuberculosis in Ecuador: a tracking update for the years 2018 and 2023
5 affiliations
- 1One Health Research Group, Universidad de Las Américas
- 2Universidad Católica de Santiago de Guayaquil
- 3Universidad Ecotec
- 4Instituto Nacional de Salud Pública e Investigación
- 5Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de Extremadura
Abstract
Introduction: The RDRio genotype of Mycobacterium tuberculosis (MTB), a major genotype within the Latin American-Mediterranean (LAM) family, has been associated with increased transmissibility and multidrug resistance (MDR). In Ecuador, a previous baseline study reported a low prevalence of 2.09% for 2012–2016, prior to the large influx of migrants from Venezuela—where RDRio is highly endemic—that has occurred since 2015. This study aimed to update the molecular epidemiology of the RDRio genotype in Ecuador.
Methods: We screened 699 clinical MTB isolates collected in 2018 (384) and 2023 (315) for the RDRio genotype by duplex PCR and further characterized them by 24-locus MIRU-VNTR typing, spoligotyping, and whole-genome sequencing (WGS). We conducted minimum spanning tree (MST) analyses based on MIRU-VNTR profiles to assess genetic relatedness.
Results: We identified 40 isolates (5.72%) as RDRio, with no significant difference in prevalence between 2018 ( n = 20; 5.21%) and 2023 ( n = 20; 6.35%). WGS confirmed that the dominant sublineages were 4.3.4.1 and 4.3.4.2, all within Lineage 4 (Euro-American). Genotypic resistance profiling classified 32.1% (9/28) of sequenced isolates as MDR-TB and 7.1% (2/28) as pre-XDR-TB. MST analysis showed that RDRio isolates from Ecuador segregated predominantly into distinct clonal complexes and remained largely isolated from international reference strains, including Venezuelan isolates.
Discussion: The overall RDRio prevalence of 5.72% represents a nearly three-fold increase relative to the 2.09% reported for the 2012–2016 baseline, although it remained stable across the 2018–2023 period and low compared with high-endemicity settings such as Venezuela. Despite this relatively low prevalence, the RDRio genotype was associated with a substantial burden of drug resistance. The genetic segregation of the predominant RDRio Ecuadorian clonal complex from international reference strains—including Venezuelan isolates—did not support recent importation associated with the Venezuelan diaspora. Despite their limitations, classical genotyping methods remain a valid, cost-effective approach to monitor MTB strains of interest associated with MDR-TB, such as RDRio, in low-resource settings like Ecuador.
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BibTeX
@article{rodriguezpazmino2026molecular,
title = {{Molecular epidemiology of the RDRio genotype of Mycobacterium tuberculosis in Ecuador: a tracking update for the years 2018 and 2023}},
author = {Ángel Sebastián Rodríguez-Pazmiño and Melany Patricia Cedeño-Vásquez and Liliam Paola Pozo-Estupiñán and Irina Trejo Cedeño and Greta Cárdenas Franco and Andrea Belén Salcedo Maldonado and Solón Alberto Orlando and Greta Franco-Sotomayor and Natalia Jimenez-Pizarro and Javier Hermoso de Mendoza and Miguel Angel Garcia-Bereguiain},
journal = {Frontiers in Public Health},
year = {2026},
month = oct,
doi = {10.3389/fpubh.2026.1969751},
url = {https://www.frontiersin.org/articles/10.3389/fpubh.2026.1969751/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Molecular epidemiology of the RDRio genotype of Mycobacterium tuberculosis in Ecuador: a tracking update for the years 2018 and 2023
AU - Ángel Sebastián Rodríguez-Pazmiño
AU - Melany Patricia Cedeño-Vásquez
AU - Liliam Paola Pozo-Estupiñán
AU - Irina Trejo Cedeño
AU - Greta Cárdenas Franco
AU - Andrea Belén Salcedo Maldonado
AU - Solón Alberto Orlando
AU - Greta Franco-Sotomayor
AU - Natalia Jimenez-Pizarro
AU - Javier Hermoso de Mendoza
AU - Miguel Angel Garcia-Bereguiain
PY - 2026
DA - 2026/10/27
JO - Frontiers in Public Health
DO - 10.3389/fpubh.2026.1969751
UR - https://www.frontiersin.org/articles/10.3389/fpubh.2026.1969751/full
AB - Introduction: The RDRio genotype of Mycobacterium tuberculosis (MTB), a major genotype within the Latin American-Mediterranean (LAM) family, has been associated with increased transmissibility and multidrug resistance (MDR). In Ecuador, a previous baseline study reported a low prevalence of 2.09% for 2012–2016, prior to the large influx of migrants from Venezuela—where RDRio is highly endemic—that has occurred since 2015. This study aimed to update the molecular epidemiology of the RDRio genotype in Ecuador. Methods: We screened 699 clinical MTB isolates collected in 2018 (384) and 2023 (315) for the RDRio genotype by duplex PCR and further characterized them by 24-locus MIRU-VNTR typing, spoligotyping, and whole-genome sequencing (WGS). We conducted minimum spanning tree (MST) analyses based on MIRU-VNTR profiles to assess genetic relatedness. Results: We identified 40 isolates (5.72%) as RDRio, with no significant difference in prevalence between 2018 ( n = 20; 5.21%) and 2023 ( n = 20; 6.35%). WGS confirmed that the dominant sublineages were 4.3.4.1 and 4.3.4.2, all within Lineage 4 (Euro-American). Genotypic resistance profiling classified 32.1% (9/28) of sequenced isolates as MDR-TB and 7.1% (2/28) as pre-XDR-TB. MST analysis showed that RDRio isolates from Ecuador segregated predominantly into distinct clonal complexes and remained largely isolated from international reference strains, including Venezuelan isolates. Discussion: The overall RDRio prevalence of 5.72% represents a nearly three-fold increase relative to the 2.09% reported for the 2012–2016 baseline, although it remained stable across the 2018–2023 period and low compared with high-endemicity settings such as Venezuela. Despite this relatively low prevalence, the RDRio genotype was associated with a substantial burden of drug resistance. The genetic segregation of the predominant RDRio Ecuadorian clonal complex from international reference strains—including Venezuelan isolates—did not support recent importation associated with the Venezuelan diaspora. Despite their limitations, classical genotyping methods remain a valid, cost-effective approach to monitor MTB strains of interest associated with MDR-TB, such as RDRio, in low-resource settings like Ecuador.
SN - 2296-2565
ER -