Journal Article

Molecular characterization of rpoB gene mutations in isolates from tuberculosis patients in Cubal, Republic of Angola

Moreno, María Milagros, Espasa Soley, Mateu, Vivas Cano, Maria Carmen, Nindia Eugénio, Arlete, Gil Olivas, Eva, Escartin Huesca, Carlos, Rando-Segura, Ariadna, Tórtola Fernández, María Teresa, Vegue Collado, Josep, Pumarola Suñe, Tomas, Molina Romero, Israel, Aznar, María Luisa, Sulleiro Igual, Elena, Zacarias, Adriano, Katimba, Domingos, Bocanegra Garcia, Cristina, Gabriel, Estevao, López García, Maria Teresa

2021

Overview

Background The importance of Mycobacterium tuberculosis strains with disputed rpoB mutations remains to be defined. This study aimed to assess the frequency and types of rpoB mutations in M. tuberculosis  isolates from Cubal, Angola, a country with a high incidence of tuberculosis. Methods All isolates included (n = 308) were analyzed using phenotypic drug susceptibility testing and GenoType MTBDR plus assay. DNA sequencing of the rpoB gene and determination of rifampicin MIC by macrodilution method were additionally performed on isolates yielding discordant results (n = 12) and those in which the mutation detected was not characterized (n = 8). Results In total, 85.1% (74/87) of rifampicin-resistant strains had undisputed rpoB mutations -S450L (49), D435V (15), H445D (3), H445Y (2), Q432ins (1), L449M plus S450F (1), S450F (1), S450W (1) and S450Y (1)-; 10.3% (9/87) had disputed rpoB mutations—L430P plus S493L (1), N437del (1), H445L (3), D435Y (2), L452P (2)-, 2.3% (2.3%) showed no rpoB mutations and 2.3% (2/87) showed heteroresistance—D435Y plus L452P and L430P plus S493L-. Conclusion Disputed rpoB mutations were common, occurring in 10.3% of rifampicin resistant isolates. Current phenotyping techniques may be unable to detect this resistance pattern. To increase their sensitivity, a lower concentration of RIF could be used in these tests or alternatively, rpoB mutations could be screened and characterized in all M. tuberculosis strains.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Analysis / Angola / Angola - epidemiology / Bacterial Proteins - genetics / Care and treatment / Clinical outcomes / Cubal / Diagnosis / DNA sequencing / DNA-Directed RNA Polymerases - genetics / Dosage and administration / Drug resistance / Drug resistance in microorganisms / Drug Resistance, Bacterial - genetics / Gene mutations / Genetic aspects / GenoType MTBDRplus VER2.0 / Genotypes / Health aspects / Humans / Hybridization / Infectious Diseases / Internal Medicine / Laboratories / Medical Microbiology / Medicine / Medicine & Public Health / Microbial Sensitivity Tests / Minimum inhibitory concentration / Mutation / Mycobacterium tuberculosis - genetics / Observations / Parasitology / Phenotyping / Resistance / Rifampicin / Rifampin / Risk factors / RNA polymerases / rpoB mutations / RpoB protein / Software / Strains (organisms) / Supranationalism / Tropical Medicine / Tuberculosis / Tuberculosis - epidemiology