Chemotherapy regimens used in retreatment of pulmonary tuberculosis: Part I. Observations on the efficacy of combinations of kanamycin, ethionamide and either cycloserine or pyrazinamide

Abstract

Summary Eighty-two patients with cultures of mammalian tubercle bacilli resistant to isoniazid (78 also resistant to streptomycin and 52 to PAS) admitted to National Jewish Hospital between December 1, 1960 and October, 1, 1962, are included in this study. They were treated with chemotherapy regimens consisting of ethionamide, kanamycin and either pyrazinamide or cycloserine. None of the primary drugs was included in the therapy regimens. Seventy-four of the 82 patients were treated continuously with antituberculosis drugs for at least 120 days. In 70 (94%) the sputum became negative on culture. Twelve patients later reverted to culture-positive. Fifty-eight (79%) of the 74 patients remained culture-negative, throughout the follow-up period. Of the 16 patients who remained or later became culture-positive, nine were again treated. Seven of the nine became culture-negative on a regimen usually consisting of at least two of the following drugs: ethambutol, capreomycin, ‘Isoxyl’. By January 1, 1964, 60 (81%) of the 74 patients who had had at least 120 days treatment were known to be still culture-negative the period of follow-up being from 21 to 37 months from the start of treatment. The incidence of toxic drug reactions does not contraindicate the use of these drug regimens. Whenever possible, pulmonary resection should be considered as soon as two consecutive sputums obtained two weeks apart are culture-negative. The availability of multiple-drug regimens suggests that the prognosis need not be poor in those patients with cultures resistant to the first-line drugs. If the second-line drugs are both properly selected and administered, the retreatment results should compare favourable with the nearly 100 per cent success initial therapy.