A descriptive study on isoniazid resistance-associated mutations, clustering and treatment outcomes of drug-resistant tuberculosis in a high burden country.

Purpose: To describe katG and inhA mutations, clinical characteristics, treatment outcomes and clustering of drug-resistant tuberculosis (TB) in the State of São Paulo, southeast Brazil.

Methods: Mycobacterium tuberculosis isolates from patients diagnosed with drug-resistant TB were screened for mutations in katG and inhA genes by line probe assay and Sanger sequencing, and typed by IS6110-restriction fragment-length polymorphism for clustering assessment. Clinical, epidemiological and demographic data were obtained from surveillance information systems for TB.

Transmission of Mycobacterium tuberculosis presenting unusually high discordance between genotypic and phenotypic resistance to rifampicin in an endemic tuberculosis setting.

Background: Since the implementation of the Xpert MTB/RIF in Sao Paulo, Brazil, numerous Mycobacterium tuberculosis isolates presenting "rifampicin-resistant genotype with rifampicin-susceptible phenotype" were observed.

Objective: To evaluate the prevalence, rpoB mutations and transmission of M. tuberculosis resistant to rifampicin on Xpert MTB/RIF but susceptible on BACTEC MGIT system, in Sao Paulo state.