A patient who had initial infection with mixed strains of drug-susceptible and multidrug-resistant tuberculosis was presumed to have acquired drug resistance before confirmation that sequential strains were genotypically distinct. Transmitted infection with mixed strains is likely underappreciated; identifying these infections requires spoligotyping and whole-genome sequencing.
Keywords: Mycobacterium tuberculosis; bacteria; drug resistance; heteroresistance; spoligotyping; tuberculosis and other mycobacteria; whole genome sequencing.