A comparative study to find out the prevalence of resistance to the major anti-TB drugs, SM, INH and PAS, under different situations was carried out. The situations considered were: (i) Sanatoria, (ii) Urban tuberculosis clinic, (iii) Rural general health dispensaries, (iv) the mass Case-finding among selected group of population and (v) survey of general population.

The prevalence of drug resistance to INH was 53%, the highest among sanatoria patients and 11%, the lowest among patients discovered in tuberculosis surveys i.e., situation (v). Among newly diagnosed culture positive tuberculosis patients of urban tuberculosis clinic, rural general health institutions and selected Case-finding programmes, i.e., situations (ii), (iii) and (iv), proportion of patients with INH resistant organisms were 26%, 33% and 16% respectively. The resistance rates were the highest in age group 25 to 44 in all 5 situations, case-wise rates were not significantly different. The prevalence of INH and streptomycin resistance among patients found in special mass Case-finding tuberculosis programme, were significantly lower than among patients attending special tuberculosis services or general health institutions.

The findings of this study show that prevalence of drug resistance among patients attending tuberculosis services and general health institutions is not a true index of the prevalence of drug resistance in the community and it varies under different situations.