Colicine Production as an Epidemiological Marker of Escherichia Coli

Abstract

THE epidemiology of Escherichia coli is poorly understood, and although serological characterisation of strains affords an excellent method of typing E. coli, it is time-consuming and can be performed only in specialised laboratories. Another method would be of value. Colicine typing as a method of differentiating strains has been used (Linton, 1960;McGeachie, 1965 ;Mustafa and Dunbar, 1970), but not so extensively as serotyping and its usefulness has not been defined.Colicine typing is simple to perform and has been found valuable in epidemiological studies on shigellae (Abbott and Shannon, 1958 ;Gillies, 1964;Hart, 1965), particularly on strains of Shigella sonnei because they are serologically and often biochemically homogeneous (Hart).This paper records our experience of colicine typing of E. coli and of the validity of the method as an epidemiological tool. Serological and colicine typing were used in this investigation to determine whether the combination of the two methods would provide a finer subdivision of strains, to show the frequency of colicine production and sensitivity among serologically defined strains, and to show any correlation between colicine types and antigenic structure of the organisms. This is particularly interesting because several workers attempting to purify colicines have observed a close association between colicines and the 0 antigen of the organism (Goebel and Barry, 1958;Hutton and Goebel, 1961;Barry, Everhart and Graham, 1963).An epidemiological application of the typing method is also reported. MATERIALS AND METHODS Specimensof faeces were collected from patients in a female, open medical ward as soon as possible after admission and thereafter at weekly intervals for 1 yr. The patients were those usually seen in a general medical ward and particularly included diabetics.

The sub-specific differentiation ofEscherichia coliwith particular reference to ecological studies in young animals including man

“…Colicine production is plasmid encoded and one (Col V) has been identified as a virulence marker (Smith, 1978). O-serogroups of E. coli can be subdivided into several colicine types although colicine typing is of limited value for epidemiological purposes because not all isolates produce colicines (Craven & Barnum, 1972;Hettiaratchy, Cooke & Shooter, 1973). However, on occasions, colicine typing has been helpful in assessing the significance of isolating the same Oserotype from an individual patient (Hettiaratchy, Cooke & Shooter, 1973) while it has been employed together with other tests for differentiating urinary isolates (Wilson, Crichton & Old, 1981) and clones of pathogenic E. coli (Achtman et al 1983).…”

Biochemical Typing of Urinary Escherichia Coli Strains by Means of the Api 20 E Enterobacteriaceae System

“…Although it is possible to obtain a more exact description of an individual E. coli strain by combined serotyping and biotyping, this is necessary in special circumstances only, e.g., cross-infection within a ward or theatre unit. An attempt was made by Hettiaratchy, Cooke and Shooter (1973) to combine serotyping and colicine typing of E. coZi strains but less than one third of the organisms tested formed demonstrable colicines and this reveals the limitations of their approach.…”

Colicin Typing of Shigella sonnei

“…Hettiaratchy et al modified this system for typing Escherichia coli. However, only one-third of the E. coli strains were typable (12).…”