Drug resistance of Mycobacterium tuberculosis in Korea.

Drug resistance of Mycobacterium tuberculosis has been investigated with isolates from patients screened from a sample population of the nationwide tuberculosis prevalence surveys or from routine cultures. The results showed a close inverse relationship between the prevalence of drug resistance and the efficiency of the past or current National Tuberculosis Control Program (NTP) treatment regimens. Individual drug resistance also showed a close relationship with the extent of use of the relevant drugs. Drug resistance was found in 38.0% of M. tuberculosis isolates from patients in the 1965 survey and remained unchanged until it increased to 48.0% in 1980. The resistance prevalence, however, dropped to 25.3% in the 1990 survey. Such a decrease coincided fairly well with a continuous increase of the treatment efficiency (from 60% in 1984 to 77% in 1989) in the 1980s. Initial drug resistance (IR) also showed a similar trend, namely 26.2% in 1965, 23.9% in 1970, 20.1% in 1975, 30.6% in 1980, 17.4% in 1985 and 15.0% in 1990. A higher prevalence of IR was observed among urban patients than rural patients and among young as opposed to old patients.