Resistance to antituberculosis drugs in Japan.

SETTING

Five years after the last survey of drug-resistant tuberculosis in Japan, a serious new phenomenon has gradually begun to appear. A nationwide survey was conducted by the Tuberculosis Research Committee.

OBJECTIVE

To determine resistance patterns to five anti-tuberculosis drugs and risk factors.

DESIGN

Cultures were obtained from patients hospitalized at 38 hospitals in various districts of Japan throughout 6 months, from 1 June through 30 November in 1992. Drug susceptibility testing was carried out in the national reference laboratory.

RESULTS AND CONCLUSIONS

Resistance to one or more drugs was found in 5.6% of new cases and 27.8% of recurrent cases (P < 0.001). About 88% of drug resistant isolates from the new cases were resistant to one drug, while 50.8% of the drug resistant isolates from the recurrent cases had resistance to two or more drugs (P < 0.001). Resistance rates to both isoniazid and rifampin in new cases was very low (only 0.14%). Primary drug resistance rates were higher in age groups less than 60 years old, compared to those of 60 years and over (P = 0.05). Compared with the rate in Japanese patients, foreign-born individuals had a higher resistance rate in the recurrent cases (P = 0.034). This survey indicated a similar trend in resistance rates to five antituberculosis drugs to those of the last survey in 1987.