Survey of hemolysin production among species of pseudomonads.

Although Pseudomonas aeruginosa has been known to produce hemolysis on blood agar plates, attempts to obtain hemolysin in broth culture filtrates of this organism have been generally unsuccessful. Bullock and Hunter (1900) noted that filtrates of 3 to 4 week old broth cultures of this organism lysed suspensions of erythrocytes of several animal species, including man. This finding was confirmed by Landsteiner and Raubilschek (1908) and Fukuhara (1909). All of these authors agreed that the hemolysin could be demonstrated only in very old nutrient broth cultures and that filtrates from young, actively growing broth cultures were always devoid of hemolytic activity. The failure of P. aeruginosa to produce a soluble hemolysin in young broth cultures has been confirmed by this author. In 1936, Birch-Hirschfeld described a cellophane plate technique for the production of staphylococcal hemolysin. This technique was extensively employed by William and Harper (1947), Marks and Vaughan (1950) and Liu (1954) in their studies of the delta hemolysin of staphylococci. Recently this cellophane plate technique was applied to the production of the soluble hemolysin by P. aeruginosa with considerable success. Since several workers (Salvin and Lewis, 1946; Christie, 1948) have reported that the hemolysis by P. aeruginosa on blood agar could be used to differentiate this species from other pseudomonads, the hemolysin production with the cellophane plate technique was also applied to examine the hemolytic activities of several other pseudomonads which resemble P. aeruginosa. The present communication describes the findings of this study.