Resistance of Mycobacterium tuberculosis to four first-line anti-tuberculosis drugs in Japan, 1997.

SETTING

Five years after the last survey of drug-resistant tuberculosis in Japan, a nationwide survey was conducted by the Tuberculosis Research Committee.

OBJECTIVE

To determine the prevalence of and risk factors for resistance to four first-line anti-tuberculosis drugs.

DESIGN

Cultures were obtained from patients hospitalized at 78 hospitals in different districts of Japan throughout a 6-month period, 1 June-30 November 1997. Drug susceptibility testing was carried out at the Research Institute of Tuberculosis, Tokyo, one of the supranational reference laboratories of the WHO/IUATLD global project.

RESULTS AND CONCLUSION

Among patients with no prior treatment, resistance to any of the four drugs was found in 10.3%, and the prevalence of primary multidrug resistance (MDR) was 0.8%. The prevalence of acquired resistance was 42.4% for any of the four drugs and 19.7% for MDR, indicating a high prevalence rate compared with those reported in the WHO/IUATLD global project. About 73% of resistant isolates from new cases were resistant to one drug, while 64.3% of resistant isolates from the re-treatment cases were resistant to two or more drugs (P < 0.0001). No significant differences in resistance rates by sex, age group, nationality, district, and/or accompanying diseases were observed in any of the new or re-treatment cases. Other factors associated with the high prevalence in re-treatment cases remain to be determined.