Complex clonal features in an mycobacterium tuberculosis infection in a two-year-old child.

The focus of this report is to describe the highly complex clonal features of the Mycobacterium tuberculosis (MTB) isolates cultured from a 2-year-old child with no risk factors for tuberculosis. Molecular analysis showed that she was coinfected by 2 MTB isolates. The coinfecting isolates showed only subtle genetic differences and shared equivalent infectivity in vitro; however, they were infecting independent anatomic sites (compartmentalized infection). One of the MTB isolates was cultured only from respiratory specimens, whereas the other was isolated from extrarespiratory site (central nervous system).