CLASSIFICATION OF SUBTYPES OF HUMAN TUBERCLE BACILLI BY PHAGE SUSCEPTIBILITY

Abstract

Phage typing of human tubercle bacilli was attempted using suitably reproducible and quantitative methods. Human tubercle bacilli could be divided into at least 2 subtypes according to susceptibilities to the 3 phages, GS4E, BKp and Bl: a highly susceptible group (Subtype 1), and a less susceptible group (Subtype 2). The strains of Subtype 2 resembled Mycobacterium bovis in lytic patterns. No correlation was found between phage types and virulence in guinea pigs or drug susceptibility. The strains of tubercle bacilli isolated from 5 patients who were suspected to be infected from a single source in an institution showed the same phage type. The results obtained suggested the usefulness of phage typing of human tubercle bacilli for epidemiologic studies.