Five-antituberculosis Drug-resistance Genes Detection Using Array System

Detection of resistance to drugs for Mycobacterium tuberculosis takes about two months from the sample collection using culture-based methods. To test a rapid method for detection of resistance for five antituberculosis drugs using DNA microarray and to examine its potential for clinical use, we employed a DNA microarray for detection of seven mutations genes related to resistance of five kinds of antituberculous drugs using Mycobacterium tuberculosis DNA isolated from sputum. The results of microarray analysis were compared with the results of a standard culture method of Lowenstein-jensen drug sensitivity testing system. DNA microarray analysis showed a high sensitivity (>90%) for all five drugs. Specificity of rifampicin and ethambutol were nearly 90%, however specificity of isoniazid (60%) and kanamycin (67%) were not enough. The amount of Mycobacterium tuberculosis DNA required for microarray analysis corresponded to at least 1-9 Acid-Fast Bacilli per 10 fields by carbolfuchsin staining. DNA microarray analysis appears to be useful for estimation of drug resistances, nevertheless its limitations. To minimize misunderstanding, it is necessary to confirm the number of bacilli in the sputum, and culture method is needed for comparison when use the PCR-based array system.