Presence of katG gene in resistant Mycobacterium tuberculosis.
It has been reported recently that isoniazid resistant strains of Mycobacterium tuberculosis have lost the katG gene which encodes the catalase-peroxidase enzyme. A 35 mer oligonucleotide probe specific for the katG gene of M tuberculosis, 3' end-labelled with digoxigenin, was constructed and hybridised with DNA extracted from 26 clinical isolates of M tuberculosis under high stringency conditions. Twenty two of these isolates were resistant to 0.2 microgram/ml isoniazid and 20 to 1.0 microgram/ml isoniazid. Semiquantitative detection of catalase did not show any discrimination between isoniazid sensitive and resistant strains. The katG gene was present in all clinical strains of M tuberculosis. Therefore, complete deletion of the katG gene does not seem to be the mechanism of isoniazid resistance in M tuberculosis strains isolated from patients in India.
Jaber
M
M
Department of Microbiology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India.
Rattan
A
A
Kumar
R
R
D000995:Antitubercular Agents / Q000494:pharmacology*; D002374:Catalase / Q000032:analysis; D004352:Drug Resistance, Microbial; D017353:Gene Deletion; D006801:Humans; D007538:Isoniazid / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D015345:Oligonucleotide Probes; D014376:Tuberculosis / Q000382:microbiology*
D000995:Antitubercular Agents; D015345:Oligonucleotide Probes; D002374:Catalase; D007538:Isoniazid