Nosocomial Mycobacterium tuberculosis transmission by brief casual contact identified using comparative genomics.

This paper reports a case of nosocomial transmission of Mycobacterium tuberculosis by brief casual contact. Routine variable number tandem repeat typing in Yamagata Prefecture, Japan found that M. tuberculosis clinical isolates from two patients showed indistinguishable genotypes. The patients had an epidemiological relationship of sharing a waiting room in a hospital on the same day. As comparative genomics detected only two single nucleotide variants between the isolates, it was concluded that recent tuberculosis transmission occurred in the waiting room. These results indicate that the physical separation of infectious tuberculosis patients is an essential control measure for preventing unpredictable nosocomial transmission by casual contact.