Hemolytic properties of some Aeromonas strains.

Considering the possible correlation between hemolytic and enterotoxigenic properties of Aeromonas strains mentioned in the literature, in the present work we studied the practical value of the hemolysis tests in the diagnosis of Aeromonas strains by using comparatively the hemolysis tube tests (with goat and sheep erythrocytes suspensions) as well as the technique on blood agar in aerobic conditions. There were studied comparatively 230 Aeromonas strains (different species: A. hydrophila, A. sobriae, A. caviae, A. veronii, A. salmonicida) isolated from different sources (meat products, fish of fresh waters, mussels, sea water, pipe water, diarrhoeal disease and animal faeces). The comparison among the used tests for proving the hemolytic activity of Aeromonas strains showed that: 61.89% and 56.51% from the total number of Aeromonas strains were hemolytic in the tube tests with 1% goat and 1% sheep erythrocytes suspensions respectively after 48 hrs followed by 51.72% and 48.25% strains by the 5% goat and 5% sheep blood agar plates respectively in anaerobiosis and after 48 hrs incubation at 37 degrees C. The highest incidence of hemolysin presence was pointed out in motile Aeromonas strains (A. hydrophila--60.11% and A. sobria--56.52%). Our results showing a high frequency of hemolytic activity among Aeromonas strains isolated especially in meat products are suggesting a possible correlation between the pathogenic potential and the hemolytic activity and are pleading for introduction of this test in the diagnosis of Aeromonas species.