Drug-resistant Tuberculosis in a Tertiary Referral Teaching Hospital of Korea

Background: Resistance of Mycobacterium tuberculosis strains is an increasing problem worldwide. Our purpose was to determine the prevalence of drug resistance (DR) and risk factors of DR in patients with tuberculosis and to assess the clinical characteristics and socioeconomic status of patients with drug-resistant tuberculosis.

Methods: We retrospectively studied drug susceptibility tests and clinical and socioeconomic records for 308 cases of culture-positive Mycobacterium tuberculosis infection, diagnosed at Mokdong Hospital, Ewha Womans University from March, 1995 to February, 2000.

Results: DR to at least one drug was identified in 75 (24.4%); the rate of primary DR, 18.7% and acquired DR, 39.3%. Multi-drug resistance (MDR) was identified in 31 (10.1%); primary MDR, 7.0% and acquired MDR, 21.4%. The risk factors of DR were previous TB treatment, pulmonary involvement and associated medical illness. DR group showed lesser adherence to treatment than the drug-sensitive group. DR group showed more frequent self-interruption of medication, lower completion rate of treatment and higher failure rate of follow-up than the drug-sensitive group. In previously treated tuberculosis patients, higher rate of overall DR and MDR, larger number of resistant drugs and more frequent self-interruption of medication were observed than newly diagnosed patients. Among DR group, acquired DR (ADR) group was older, less educated and treated for longer duration and had more advanced disease than primary DR group.

Conclusion: Previously treated tuberculosis is a most important risk factor for DR. DR group, especially ADR, showed less compliance with treatment. More proper education and attention to prevent self-interruption should be given to a previously treated group. In TB prevalent areas, it should be considered to obtain initial drug susceptibility testing in high risk of DR.