Bacterial Hemolysins Research Articles

Kinetic aspects of hemolysis by the alpha-toxin of Clostridium welchii and its inhibition by antitoxin.

The activity of the bacterial hemolysins in vitro can be measured quantitatively by the spectrophotometric determination of liberated hemoglobin, and is specifically inhibited by homologous antibody. The antigen-antibody reaction can be made both quantitative and sensitive and should constitute a useful model for a variety of purposes. Exploratory studies with a number of bacterial hemolysins suggested that the a-toxin of Clostridium welchii might be one of the most satisfactory, in part because of its stability in dry form, and because it is one of the better known bacterial hemolysins. This toxin has been differentiated from the other toxic components of filtrate of CI. welchii cultures and has assumed some general interest because of its predominant role in the pathogenesis of infections by this microorganism, and because it is known to have, or be associated with, lecithinase activity. The literature to 1943 has been summarized by Oakley (1943). Preliminary experiments indicated that the kinetics of a-toxin hemolysis and its inhibition by antitoxin are too poorly understood to allow the accurate titration of toxin and antitoxin. Macfarlane and Knight (1941), who established the enzymatic basis of the Nagler reaction and associated it with a-toxin,

Studies on the Nature of Bacterial Hemolysin and Proteolysin.

Many cultures of staphylococci and colon bacilli recently isolated from lesions are hemolytic when grown on blood containing media and usually such organisms are proteolytic when grown in nutrient gelatin. It has not been determined whether the hemolysin is identical with or produced parallel to the proteolytic substance. Both qualities are frequently transient and may exhibit a parallel decline. An attempt was made to study these substances with reference to individuality, interdependence or homologous nature. Filtrates of broth cultures were tested for hemolytic activity as follows: measured quantities of filtrate were added to tubes containing 1 cc. each of a 0.5% suspension of washed red blood cells, incubated at 37°C., for 1 hour, placed in the refrigerator over night and the amount of lysis observed. Proteolytic activity was determined by streaking filtrate upon the surface of an agar-gelatin medium, incubating at 37°C., for 48 hours and testing for lytic action by flooding the plate with an acid bi-chloride of mercury solution according to the method of Frazier and noting any change in the character of the gelatin as indicated by a clear zone at the site of “planting”. Filtrates of 4 to 8 day broth cultures of a proteolytic and hemolytic, Gram negative, motile organism, of intestinal origin and considered as belonging to the colon group were very active in lysing red blood cells and in digesting gelatin. In filtrates heated to 55°C., for 5 minutes the hemolysin was destroyed, while the proteolysin was destroyed only after 30 minutes at that temperature. In absorption experiments it was found that by incubation of the active filtrate with red blood cells at low temperature it was possible to absorb and remove all of the hemolysin without marked decrease in proteolytic activity of the filtrate.

Anemia Produced by Bacterial Hemolysins

Anemia Produced by Bacterial Hemolysins

A lipolytic form of hemolysis

The varieties of hemolysis hitherto described imply the direct action of certain chemically-defined bodies, acids, alkalis, glucosides, — which attack and destroy the integrity of the red corpuscles, and other chemically undefined bodies, — bacterial hemolysins, which act in the same manner, and the more indirect action of certain complexes defined as intermediary body and complement. I have shown previously that certain soaps and fatty acids — of the oleic series, chiefly — can play the part of complements in hemolysis. The experiments based upon this fact led me to the study of the ferment lipase as the direct or indirect cause of hemolysis. I found in the course of this study that lipase is, under some conditions, an efficient hemolytic agent which acts, however, not directly upon the red corpuscles, but indirectly through the liberation from available fats of the active fatty acids. Neutral fats, the higher glycerides, are not hemolytic, but they become so under the influence of lipase.If one drop of ...