Reinfection and Mixed Infection Cause Changing <i>Mycobacterium tuberculosis</i> Drug-Resistance Patterns

We have shown that, in some patients with MDR tuberculosis, mixed infection may be responsible for observations attributed to reinfection by DNA fingerprinting. We conclude that treatment and adherence determines which strain is dominant. We hypothesize that treatment with second-line drugs may lead to reemergence of the drug-susceptible strain in patients with mixed infection.