[Frequency of MDR-TB/XDR-TB strains isolated from chronic pulmonary tuberculosis patients in Japan].

PURPOSE To observe the frequency of MDR-TB/XDR-TB strains isolated from chronic pulmonary tuberculosis patients in Japan. OBJECT Ad hoc National Tuberculosis Survey 2000 on frequency of MDR-TB and XDR-TB strains. MATERIALS AND METHOD Four hundred and thirty four clinical isolates were collected by the Ad hoc National Tuberculosis Survey 2000, the drug susceptibility testings (proportion method, MGIT Middlebrook, and BrothMIC NTM) were conducted on these strains. These clinical isolates were obtained from patients registered at Health Centers in Japan by the end of 1999 who were culture-positive in 1999 and were registered before January 1st, 1998. The isolates used in this study were selected from patients who were culture-positive at shortest 2 years after the registration. RESULT The clinical isolates resistant to both INH and RFP were 321 out of 434 (74.0%). The 180 MDR-resistant clinical isolates were also resistant to levofloxacin and amikacin and/or kanamycin. These phenotypes are XDR-TB. No previously registered cases were 165, and previously registered cases were 143 and unknown cases were 13 out of 321 MDR-TB. In 180 XDR-TB cases, no previously registered cases were 95, previously registered cases were 78 and unknown cases were 7. In no previously registered cases, more than 50% cases started treatment in 1990s. Approximately 50% of previously registered patients started treatment in 1960s and 1970s. CONCLUSION We performed drug susceptibility testing for 434 clinical isolates which were culture-positive at shortest 2 years after registration. No. of MDR-TB patients was 321 and that of XDR-TB patients was 180. The treatment outcome of these patients have to be followed up carefully at Health Centers. The frequency of amikacin resistance was relatively high. This may be due to either common use of amikacin or cross-resistance against streptomycin and kanamycin.