Culture-independent prediction of isoniazid resistance in Mycobacterium tuberculosis by katG gene analysis directly from sputum samples

Heinz Rinder, Knut Feldmann, Enrico Tortoli, Jacques Grosset, Manuel Casal, Elvira Richter, Mohammed Rifai, Vincent Jarlier, Manuel Vaquero, Sabine Rüsch-Gerdes, Emmanuelle Cambau, Juan Gutierrez, Thomas Löscher

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Background: The molecular prediction of isoniazid (INH) resistance in Mycobacterium tuberculosis is hampered by the need for specialized equipment, expertise, high costs, a limited range of detectable mutations, or several of these factors. The rationale for the study was to find a practical alternative and to demonstrate generally valid problems. Methods and Results: DNA extracted from decontaminated sputum pellets was used to amplify a 0.26 kb target sequence within the katG gene. Mutations of codon 315, frequently found in isoniazid-resistant isolates, could be discriminated in a simple agarose minigel format following an AciI digest of the nested polymerase chain reaction (PCR) product. Within a panel of 22 sputum samples, INH resistance could be predicted in 5 of 10 samples containing isoniazid- resistant M. tuberculosis. The protocol is robust, requires little expertise and no specialized equipment, and provides the test results within 2 days. Conclusion: The results show the feasibility to rapidly and easily detect mutations highly predictive of isoniazid resistance. Nevertheless, this, like any other molecular resistance prediction test, is affected by often neglected factors, including mutation prevalences, the phenomenon of heteroresistance, and a possible bias toward one's own method.

Original languageEnglish (US)
Pages (from-to)145-152
Number of pages8
JournalMolecular Diagnosis
Issue number2
StatePublished - 1999
Externally publishedYes


  • Genotyping
  • Heteroresistance

ASJC Scopus subject areas

  • Medicine(all)


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