Some biological features of Proteus bacilli. 2. Haemolytic activities of Proteus mirabilis and Proteus vulgaris strains.

The haemolytic activities of Proteus mirabilis and P. vulgaris strains were studied under different conditions. No filterable alpha haemolysin could be detected in P. mirabilis uropathogens provided from patients with urinary tract infections. Together with the results presented in the accompanying paper, in which three clinical isolates with temporary ability to produce a soluble haemolysin were described, the occurrence of alpha haemolytic P. mirabilis isolates did not exceed 3%. Cell bound beta haemolysin is present in nearly 35% of P. mirabilis urinary strains. Another kind of haemolytic activity was observed when P. mirabilis and P. vulgaris strains were grown in liquid media supplemented with erythrocytes. During the logarithmic growth phase nearly 100% of P. mirabilis and P. vulgaris strains of various origin haemolyzed 100-50% of erythrocytes. Except for Serratia, the other representatives of Enterobacteriaceae did not demonstrate such activity in the same conditions. The preliminary characteristics of this phenomenon is given.