Some studies on the epidemiology of sonne dysentery. Changes in colicine type and antibiotic resistance between 1956 and 1965

Abstract

The colicine type and antibiotic resistance have been determined on strains of Sh. sonnei derived from 9419 incidents of Sonne dysentery in London between October 1956 and March 1965. The most striking observation has been the appearance of strains with patterns of colicine production and antibiotic resistance new to the area. These changes are best regarded as a result of the interaction and transfer of characters between Sh. sonnei and other intestinal organisms. The general tendency has been for strains of Sh. sonnei to become increasingly resistant to antibiotics but this has not been an uninterrupted process. The proportion of drug-resistant strains at any one time depended on the properties of the current epidemic strain. Spread of Sonne dysentery was essentially local, but some strains of Sh. sonnei were found to spread much more widely than others. Most, but not all, of the strains resistant to streptomycin and tetracycline possessed only limited powers of spreading.