Study on genetic microarray for detection of katG mutations associated with Mycobacterium tuberculosis resistance to INH

Objective To establish and evaluate a gene microarray for determination katG mutations of Mycobacterium tuberculosis isolates associated with resistance to isoniazid(INH).Methods A panel of probes were designed and gene chips were prepared by dotting.Mycobacterium tuberculosis isolates resistance to 5 drugs was determined by proportional dilution methods.Amplicons of Mycobacterium tuberculosis isolates were detected by our chip and sequenced.Results The drug resistance rate of the isolates to at least one of the anti-tuberculosis drugs was 70.8%(97/137).45 strains out 137 Mycobacterium tuberculosis isolates was resistant to INH(32.8%).katG was successfully amplified from 100% of the susceptible strains and 88.9%(40/45)resistant strains.4 of 45 INH resistant isolates' katG were deleted.27 of 40(67.5%) katG has been detected to have katG 315 codon mutations.The mutations were 315 AAC(Asn,13/40), ACC(Thr,6/40),ACA(Thr,4/40),ATC(Ile,2/40),AGC(Arg,2/40).The mutation rate of katG analyzed by gene chips we prepared were identical to katG sequencing.Conclusion The gene microarray techniques we developed for determination of Mycobacterium tuberculosis resistance to INH are specific, sensitive and may be used as an alternative in clinical laboratory.