Implications of emerging isoniazid resistance in Mycobacterium tuberculosis in Korea

In 1981, the Korean National Institute of Health (KNIH) reported that 17% of all tuberculosis patients had primary resistance to isoniazid while an additional 17% acquired isoniazid resistance during chemotherapy. This 34% isoniazid resistance rate in the Republic of Korea, where an estimated 6-8% of the total population have active tuberculosis, poses significant concerns regarding management of U.S. military health care beneficiaries who develop tuberculosis or have tuberculosis skin test conversion while residing in or after departure from Korea. To address this issue, the prevalence of Korean acquired isoniazid resistance was estimated in U.S. beneficiaries by performing antibiotic sensitivities on all positive cultures from October 1981 through December 1982. Of 42 patient isolates, six were isoniazid resistant (14.3%). When the data was analyzed further, it was determined that as many as 9.5% of those U.S. beneficiaries infected had primary isoniazid resistance. This is higher than the most recent U.S. population-based drug resistance study, in which 6.9% of tuberculosis patients had primary drug resistance. This data comparison points toward the need for judicious management of Korean acquired infections and skin test conversions. Emphasis is on criteria necessary to warrant use of chemotherapeutic agents other than isoniazid to prevent further introduction of resistant organisms into locales where isoniazid resistance is not as prevalent as reported in Korea.