OBJECTIVE: To analyze and compare the mutations in two different regions of the katG gene, which is responsible for isoniazid (INH) resistance. METHODS: We analyzed 97 multidrug-resistant Mycobacterium tuberculosis strains isolated in cultures of sputum samples obtained from the Professor Hélio Fraga Referral Center, in Brasília, Brazil. Another 6 INH-sensitive strains did not present mutations and were included as controls. We used PCR to amplify two regions of the katG gene (GenBank accession no. U06258)-region 1, (from codon 1 to codon 119) and region 2 (from codon 267 to codon 504)-which were then sequenced in order to identify mutations. RESULTS: Seven strains were resistant to INH and did not contain mutations in either region. Thirty strains carried mutations in region 1, which was characterized by a high number of deletions, especially at codon 4 (24 strains). Region 2 carried 83 point mutations, especially at codon 315, and there was a serine-to-threonine (AGC-to-ACC) substitution in 73 of those cases. The analysis of region 2 allowed INH resistance to be diagnosed in 81.4% of the strains. Nine strains had mutations exclusively in region 1, which allowed the proportion of INH-resistant strains identified to be increased to 90.6%. CONCLUSIONS: The number of mutations at codon 315 was high, which is consistent with cases described in Brazil and in other countries, and the analysis of region 1 resulted in a 9.2% increase in the rate at which mutations were identified.
OBJECTIVE: To analyze and compare the mutations in two different regions of the katG gene, which is responsible for isoniazid (INH) resistance. METHODS: We analyzed 97 multidrug-resistant Mycobacterium tuberculosis strains isolated in cultures of sputum samples obtained from the Professor Hélio Fraga Referral Center, in Brasília, Brazil. Another 6 INH-sensitive strains did not present mutations and were included as controls. We used PCR to amplify two regions of the katG gene (GenBank accession no. U06258)-region 1, (from codon 1 to codon 119) and region 2 (from codon 267 to codon 504)-which were then sequenced in order to identify mutations. RESULTS: Seven strains were resistant to INH and did not contain mutations in either region. Thirty strains carried mutations in region 1, which was characterized by a high number of deletions, especially at codon 4 (24 strains). Region 2 carried 83 point mutations, especially at codon 315, and there was a serine-to-threonine (AGC-to-ACC) substitution in 73 of those cases. The analysis of region 2 allowed INH resistance to be diagnosed in 81.4% of the strains. Nine strains had mutations exclusively in region 1, which allowed the proportion of INH-resistant strains identified to be increased to 90.6%. CONCLUSIONS: The number of mutations at codon 315 was high, which is consistent with cases described in Brazil and in other countries, and the analysis of region 1 resulted in a 9.2% increase in the rate at which mutations were identified.
Authors: Graziele Lima Bello; Franciele Costa Leite Morais; Sheile Pinheiro de Jesus; Jonas Michel Wolf; Mirela Gehlen; Isabela Neves de Almeida; Lida Jouca de Assis Figueiredo; Tainá Dos Santos Soares; Regina Bones Barcellos; Elis Regina Dalla Costa; Silvana Spíndola de Miranda; Maria Lucia Rosa Rossetti Journal: Mem Inst Oswaldo Cruz Date: 2020-04-17 Impact factor: 2.743
Authors: Jessica N Torres; Lynthia V Paul; Timothy C Rodwell; Thomas C Victor; Anu M Amallraja; Afif Elghraoui; Amy P Goodmanson; Sarah M Ramirez-Busby; Ashu Chawla; Victoria Zadorozhny; Elizabeth M Streicher; Frederick A Sirgel; Donald Catanzaro; Camilla Rodrigues; Maria Tarcela Gler; Valeru Crudu; Antonino Catanzaro; Faramarz Valafar Journal: Emerg Microbes Infect Date: 2015-07-15 Impact factor: 7.163
Authors: Flávia A D de Freitas; Vagner Bernardo; Michel K Gomgnimbou; Christophe Sola; Hélio R Siqueira; Márcia A S Pereira; Fátima C O Fandinho; Harrison M Gomes; Marcelo E I Araújo; Philip N Suffys; Elizabeth A Marques; Rodolpho M Albano Journal: PLoS One Date: 2014-08-05 Impact factor: 3.240