Use of host modified bacteriophages in development of a phage typing scheme for Clostridium perfringens

A bacteriophage isolated from a faecal strain of Clostridium perfringens was adapted to a number of host strains of clinical swab and faecal isolates. A typing scheme was developed using nine host modified phages. Of 109 strains the phage types of 57 (52.3%) were identified. Nine (8.2%) other strains were sensitive to the phages at varying degrees. The remaining 43 (39.4%) strains were resistant. Eleven of the 57 typable strains yielded cell-surface mutants which belonged to different phage types from their parent strains. The phages were applied at two different dilutions in a reverse spotting method to eliminate false positive reactions due to inhibition by phage adsorption or bacteriocins. The method was simplified with the aid of a multipoint inoculator for routine use.