Bacteriophage and bacteriocin typing scheme for Clostridium difficile

The study of the epidemiology of infection with Clostridium difficile would be aided by a way to type individual bacterial isolates. We therefore sought bacteriophages for use in typing. With mitomycin C exposure (3 micrograms/ml), filtrates from 10 strains of C. difficile had plaque-forming lytic activity on other C. difficile strains. Individual phage were passaged and made into high-titer stock preparations for typing. Electron microscopy revealed tailed phage particles from one such preparation. In addition to phage, inhibitory activity without distinct plaque formation consistent with bacteriocins was observed for 20 strains. C. difficile isolates from 16 patients taken 1 to 14 days apart were similar in their phage sensitivity pattern, whereas isolates from separate geographic locations showed a great variety of patterns. We conclude that bacteriophage should be useful for typing strains of C. difficile.