Development of rapid drug susceptibility testing provides the opportunity for rapid identification of individuals with drug resistant tubercle bacilli, allowing selection of appropriate therapeutic regimens.

A total of 502 drug resistant isolates were subjected to reverse blot hybridization assay to detect mutations within genes (rpoB, katG, inhA, and ahpC) associated with rifampicin (RMP) and isoniazid (INH) resistance.

Among the 264 RMP resistant strains (RMP^R) tested, the most prevalent mutation was the Ser531Leu seen in 121 strains (46%). The second common mutation occurred in 84 strains (32%) at codon 526. And 27 strains (10%) showed the mutation at codon 516. Among all 469 INH resistant strains (INH^R), the katG mutation was responsible for INH. The inhA mutation was present in 88 strains (19%). In 11 isolates (2%), coexisting of the katG and inhA mutations were identified. Reverse hybridization assay successfully detected over 80% of INH^R and over 92% of RMP^R among Korean isolates.

Reverse hybridization was useful for rapid detection of INH^R and RMP^R.