Title: Molecular mechanisms of drug resistance in Mycobacterium tuberculosis clinical isolates
Abstract:Abstract Objective To study the molecular mechanisms of drug resistance in Mycobacterium (M) tuberculosis , to evaluate the value of the β subunit of RNA polymerase (rpoB), the ribosomal siz protein (...Abstract Objective To study the molecular mechanisms of drug resistance in Mycobacterium (M) tuberculosis , to evaluate the value of the β subunit of RNA polymerase (rpoB), the ribosomal siz protein (rpsL), 16Sr RNA (rrs), catalase peroxidase gene (katG) genes, and inhA regulatory sequence as genetic markers for rifampin (RFP), streptomycin (SM), isoniazid (INH) resistance, and to develop new methods for detecting the drug resistance Method The rpoB, rpsL, rrs, katG genes, and inhA regulatory sequence in 85 M tuberculosis isolates were analyzed with polymerase chain reaction (PCR), PCR single stranded conformation polymorphism analyses (SSCP), PCR nucleotide sequence analyses (NS) and PCR restriction fragment length polymorphism (RFLP) Results The sensitivity of amplifying the drug resistant genes with PCR was 1-10 pg DNA Twenty eight drug sensitive strains had no alterations in the rpoB, rpsL, rrs, katG genes, and inhA regulatory sequences 93 3% of 45 M tuberculosis RFP resistant (RFP r) isolates had rpoB mutations Codon 531 and 526 of the rpoB are the most common sites of nucleotide substitutions 72 5% of 40 SM resistant (SM r) isolates had an identical mutation at codon 43 of the rpsL gene No isolates had a mutation at codon 88 of the rpsL Only 7 5% of these SM r isolates had A to C transversions at position 513 of the rrs gene Of 34 INH resistant (INH r) isolates, 11 8% had complete katG deletions, 55 9% had mutations in the selected region of katG Only 8 8% had alterations in the inhA regulatory sequences 60 9% of RFP r, INH r, and SM r isolates had mutations in genetic markers for these drug resistance Conclusions Most drug resistance in M tuberculosis was due to simple mutations occurring in chromosomally encoded genes Alterations in rpoB, rpsL and katG gene may be the important mechanism of M tuberculosis resistance to RFP, SM, and INH PCR, PCR SSCP, PCR NS, and PCR RFLP are going to become the simple, rapid and reliable diagnostic tests for drug resistance in M tuberculosis n polymorphism · nucleotide sequence analyses · restriction fragment length polymorphism · Mycobacterium tuberculosisRead More
Publication Year: 1999
Publication Date: 1999-01-01
Language: en
Type: article
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