Isolation and selection of a bacteriophage-typing set for Enterobacter cloacae

Seventy-six phages active against Enterobacter cloacae were isolated from sewage and other sources. They were tested at RTD on 92 selected strains of E. cloacae and their lytic reactions were used to select phages for a typing set. Numerical analysis by the Jaccard coefficient was used to assess the similarity between the phages. A computer-based test selection procedure selected sub-sets of phages to discriminate between all 92 E. cloacae strains and within the most frequent serological groups. A subjective analysis of the candidate phages based on similarity, clarity of plaque and frequency of lysis was combined with the computer selected sub-sets to produce a final set of 25 phages that gave a good theoretical discrimination of clinical isolates of E. cloacae.