Use of bacteriophage typing to distinguish Propionibacterium acne types I and II.

Strains of serotypes I and II of Propionibacterium were compared for phage sensitivity. The two serotypes could be distinguished by using a typing set consisting of 16 bacteriophages at concentrations that demonstrated selective lysis of serotype I or II bacterial strains. Seven phage types were found; three were composed exclusively of serotype I, and four were exclusively composed of serotype II organisms. Generally, serotype I strains were more sensitive to phage lysis than were serotype II strains. No correlation was found between phage type and site of isolation.