Prevalence of drug resistant TB

As published in the New England Journal of Medicine, results of a 3 year study over 1994-97 conducted over 5 continents into anti-tuberculosis drug resistance found

that among patients with no prior treatment, a median of 9.9% of Mycobacterium tuberculosis strains were resistant to at least one drug

leaving them no option but to conclude that

Resistance to antituberculosis drugs was found in all 35 countries and regions surveyed, suggesting that it is a global problem

Importantly these rates were experienced in people with no prior treatment which indicates that a significant quantity of drug resistant TB is being acquired by transmission not by faulty or interrupted TB treatment.

It is logical to assume that the rates for drug resistance in active TB are applicable to latent TB.