Colony Incompatibility among New Zealand Isolates of Salmonella typhimurium

Strains of Salmonella typhimurium representing various phage-types were permitted to swarm towards each other on soft agar to determine their compatibility. Some strains, regardless of phage-type, were totally compatible, whereas others regularly formed incompatibility zones. The widths of these zones varied from less than 1 mm to 12 mm. A detailed study of 30 strains of phage-types 1 and 42 showed that they belonged to a variety of incompatibility groups, while four strains of phage-type 179, which was only recently found in New Zealand, all belonged to one incompatibility group.