Chemotherapy of drug resistant tuberculosis: the Tuberculosis Research Centre experience over 40 years.

Tuberculosis Research Centre (ICMR)

Indian Journal of Tuberculosis; 2000; 47; 201-210.          

A retrospective review was undertaken of randomized controlled clinical trails done at the Tuberculosis Research Centre, Chennai during the past 4 decades to assess the response to primary and retreatment drug regimens in patients found resistant to Streptomycin, Isoniazid and Rifampicin. SCC regimens were found to be effective in patients with S resistance. For patients who had SH resistance, in the Pre-Rifampicin era, the retreatment regimens (containing Ethionamide, Pyrazinamide, Cycloserin) available were less effective, toxic and unacceptable to most patients. In post-Rifampicin era, SCC regimens containing R and Z in addition to E or S gave excellent results. Besides, 91% of H or SH resistant patients became culture negative when treated with 12 RE plus 3 months of Kanamycin.

      The number of drugs in the regimen, the rhythm of administration of Rifampicin and also other companion drugs influenced the treatment outcome in patients with SH resistance. Patients with Rifampicin resistance failed to respond to primary SCC regimens. Even with individually tailored regimens, containing drugs like Ofloxacin, PAS, Thioacetazone and Amikacin, the success rate was only 50% and the mortality rate was high (34%).

      Retreatment of MDR-TB cases is, therefore, unsatisfactory at present. The best approach remains to cure patients during primary treatment with standardized SCC regimens and supervised chemotherapy (DOTS) in order to prevent the development of drug resistance, especially to RH.

Keywords : Chemotherapy of drug resistance, MDR-TB, Resistant tuberculosis, Pulmonary tuberculosis

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