Rapid detection of isoniazid resistance in mycobacterium tuberculosis probes for selecting nucleic acid encoding isoniazid resistance, and methods and kits

A process for detecting in vitro the presence of cells of a Mycobacterium tuberculosis which is resistant to isoniazid, wherein the process comprises the steps of:

• (A) depositing and fixing nucleic acids of the cells on a solid support, so as to make the nucleic acids accessible to a probe;
• (B) contacting said fixed nucleic acids from step (A) with a probe under conditions permitting selective hybridization;
• (C) washing said solid support resulting from step (B), so as to eliminate any non-hybridized probe;
• and then
• (D) detecting any hybridized probe on said washed solid support resulting from step (C) as an indication of the presence of nucleic acids of a Mycobacterium tuberculosis which is resistant to isoniazid;
• wherein said probe comprises a nucleic acid which encodes a polypeptide of the formula APLNSWPDNASLDKARRLLWPSKKKYGKKLSWADLIV (SEQ ID NO:8).

A method of detecting the presence of Mycobacterium tuberculosis which is resistant to isoniazid in a bacteria-containing sample comprising

• (A) providing a sample suspected of containing Mycobacterium tuberculosis which is resistant to isoniazid;
• (B) lysing the bacteria in said sample to release their DNA;
• (C) denaturing said released DNA;
• (D) providing a probe, which is capable of stably hybridizing to DNA from Mycobacterium tuberculosis species which are resistant to isoniazid, wherein said probe comprises a 2.5 kb EcoRV-KpnI fragment of plasmid pYZ55, wherein said fragment contains a BamHI cleavage site;
• (E) contacting said DNA probe with said released DNA in said sample under conditions which allow said probe to selectively hybridize to DNA from Mycobacterium tuberculosis which is resistant to isoniazid, if present in said sample, to form hybrid DNA complexes;
• and
• (F) detecting said hybrid DNA complexes as an indication of the presence in said sample of Mycobacterium tubercuriosis which is resistant to isoniazid.