Colicine production as an epidemiological marker of Shigella sonnei

Abstract

1. Modifications of the technique of colicine typing are reported which allow more rapid and economical identification of Shigella sonnei for epidemiological purposes without loss of accuracy.2. The technique is epidemiologically valid as judged by the constancy of type in repeated isolations from individuals and the uniformity of type in epidemics; it is considered that the few instances of lack of uniformity in these indices are probably examples of true mixed type infection. There is no evidence of type instability in vitro.3. Type incidence differs significantly from that reported in two other centres; a new colicine type (Type 14) is described which brings the total of recognizable types to 16. It is considered that in addition to the five types which were previously thought distinctive, three other Types, 6, 11 and 14, can now be so regarded.4. There is a need for continued studies to resolve the few discrepancies associated with infection by more than one type either in the individual or in an epidemic; it is hoped that colicine typing will reawaken interest in Sonne dysentery.This investigation was supported (in part) by Public Health Service Research Grant AI– 04833–01.from the National Institute of Allergy and Infectious Diseases.