Use of bacteriophage as a marker for identification of freshly-isolated individual eschrichia coli strains

Abstract

One or more of 24 selected bacteriophages at 100 and 1000 times routine test dilution (RTD), spotted on lawns of individual Escherichia coli strains were found to attack over 90% of 297 E. co/i strains tested.lt was found that in most cases, it may be possible to use the phage susceptibility pattern of an individual E. coli strain as an identifying marker for that strain. In four cases, E. coli strains with the same phage pattern, isolated from different individuals, were found to belong to the same serogroup. Similarly, of 16 enterotoxigenic Escherichia coli (ETEC) isolates from 75 contacts of cases with watery diarrhoea, 7 were found to have the same phage pattern as ETECs from their respective index case. The toxigenic character of each pair was also found to be identical. The practicality of using phage patterns for studying the dynamics of E. coli population was demonstrated by its ability to detect changes in the E. coli population in a single patient