title: Hemolytic activity in enterotoxigenic and non-enterotoxigenic strains of Escherichia coli.
abstract: We screened 223 strains of Escherichia coli belonging to serotypes previously associated with the production of enterotoxin for hemolytic activity, using horse erythrocytes in liquid and in agar media. Thirty-eight were hemolytic. They belonged to nine different serotypes; most (65.8%) belonged to one serotype, O6: H-. Additionally, all 38 strains were specifically assayed for a filterable, heat-labile hemolytic activity previously associated with a hemolysin plasmid. A comparison of hemolytic activity and enterotoxicity showed that none of 32 strains hemolytic in both media was enterotoxigenic; 28 of the 32 expressed heat-labile hemolytic activity. Four of the six strains hemolytic in only one of the media were enterotoxigenic; none of these six expressed heat-labile hemolytic activity. Of 223 strains, 176 that were of human origin and isolated in the United States were further assayed for three traditionally plasmid-mediated characteristics: heat-labile enterotoxin, heat-stable enterotoxin, and colonization factors. The interrelationships of these characteristics, including hemolytic activity, may reflect varying degrees of plasmid compatibility.
mesh_terms: D000818:Animals; D001769:Blood / Q000382:microbiology; D004768:Enterotoxins / Q000096:biosynthesis*; D004912:Erythrocytes / Q000276:immunology; D004926:Escherichia coli / Q000145:classification / Q000276:immunology*; D004927:Escherichia coli Infections / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D006461:Hemolysis; D006736:Horses / Q000276:immunology; D006801:Humans; D012703:Serotyping; D014556:Urine / Q000382:microbiology; D014947:Wounds and Injuries / Q000382:microbiology
chemical_list: D004768:Enterotoxins