Detection of rifampin resistance among isolates of Mycobacterium tuberculosis from Mozambique

Microb Drug Resist. Winter 1995;1(4):321-6. doi: 10.1089/mdr.1995.1.321.


Rifampin resistance in respiratory isolates of Mycobacterium tuberculosis from Mozambique was detected by screening for point mutations using polymerase chain reaction (PCR) and DNA sequence analysis. The target template was a 350-bp fragment of rpoB encoding the beta-subunit of the RNA polymerase. Of the 66 strains studied, 38 were rifampin resistant by susceptibility testing with the radiometric method, 3 were intermediately resistant, and 25 were susceptible to rifampin. In 39 of the 41 rifampin-resistant strains, base-substitutions in the rpoB fragment were detected, and a total of 13 distinct mutations affecting 6 amino acids were observed. One of these mutations (His-->Thr in amino acid 526) was not previously described. The isolates were also investigated by restriction fragment length polymorphism (RFLP) analysis using the insertion element IS6110 as a hybridization probe. A total of 47 RFLP patterns were identified, with up to 9 isolates having the same RFLP pattern. Strains with the same RFLP pattern harbored different mutations in rpoB, suggesting that acquisition of rifampin resistance followed the spread of a rifampin-susceptible clone. The data showed that rifampin resistance can be detected with a high sensitivity by DNA sequence analysis of this fragment of rpoB. However, a few strains with rifampin resistance due to factors other than base substitutions in rpoB could be missed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antibiotics, Antitubercular / pharmacology*
  • Base Sequence
  • DNA, Bacterial / analysis
  • DNA, Bacterial / isolation & purification
  • Drug Resistance, Microbial
  • Humans
  • Microbial Sensitivity Tests
  • Molecular Sequence Data
  • Mozambique
  • Mycobacterium tuberculosis / drug effects*
  • Nucleic Acid Hybridization
  • Polymerase Chain Reaction
  • Polymorphism, Restriction Fragment Length
  • Rifampin / pharmacology*
  • Tuberculosis, Pulmonary / microbiology*


  • Antibiotics, Antitubercular
  • DNA, Bacterial
  • Rifampin