Some biological features of Proteus bacilli. 1. Comparison of Proteus mirabilis strains provided from various sources.

Some properties which may contribute to the pathogenicity of Proteus mirabilis were compared in urinary isolates and in strains provided from soil and from culture collection. Clinical isolates revealed the higher expression of all the features examined in this report: swarming growth, haemagglutination, adherence to human uroepithelial cells, urease activity and haemolytic activity. Noteworthy is the higher mean value of adherence to the uroepithelial cells in clinical strains. Three P. mirabilis urinary isolates were detected which produce an as yet unreported filterable haemolysin. However, the loss of this ability within a few months seems to suggest the temporary presence of a plasmid rapidly eliminated by the Proteus strains.