Primary and secondary resistance of mycobacterium tuberculosis in Eastern Botswana.

Of 51 patients in Eastern Botswana who denied previous anti-tuberculosis treatment, 6 (11.8 %) were excreting tubercle bacilli resistant to one of the first-line drugs in regular use: 4 patients (7.8 %) showed resistance to isoniazid, 2 (3.9 %) to thiacetazone and none to streptomycin. Of 44 patients known to have been on previous anti-tuberculosis treatment, 31 (70.5 %) were found to show resistance to one or more of the first line drugs: 31 (70.5 %) to isoniazid, 12 (27.2 %) to streptomycin and 11 (25.9 %) to thiacetazone. No appreciable resistance was found to second line drugs. These resistance patterns, which correspond quite well with other published results from Africa, are related to the overall problem in Botswana, namely the failure of a high proportion of patients, to complete a full course of first line treatment.