Bacillus diphtheriae in its Relationship to Bacteriophage

Abstract

The intimate relationships between bacteriophage and the elementary diphtheria organism are obscure, and the fact that all strains of the bacillus thus far isolated from field cultures yield lytic filtrates suggests that the diphtheria "bacillus" as we know it may be most complex. Coccoid forms occurring in the transformation of the susceptible derivative and the coccus stage appearing in the development of the bacillary form from the filter-passing stage may well be worthy of consideration. Studies thus far made by the writers do not justify the conclusion that the diphtheria bacillus as we know it is always a lysogenic culture, that is, a being in which the bacterium is uniformly found in association with bacteriophage, possibly an obligate symbiosis. Diphtheria bacteriophage would seem to be fully as common as is bacteriophage for B. coli or for pyogenic cocci. Its demonstration in sewage, in patients, in convalescents, in field cultures, and under certain circumstances in dust and air, suggests that it may play a significant role under many circumstances, and offers to the epidemiologist an additional point of attack in the study of those conditions governing the behavior of communicable disease.