title: Contact-haemolysin production by entero-invasive Escherichia coli and shigellae.
abstract: Entero-invasive Escherichia coli (EIEC) and shigellae were tested for contact-haemolysin (CH) with red blood cells (RBCs) of guinea-pig, rabbit, rat, mouse, monkey, man, sheep and chicken; all bacteria showed the best lysis with guinea-pig RBCs. The best culture medium for CH activity of shigellae was tryptic soy broth, and for EIEC it was casamino acid-yeast extract broth with 1 mM CaCl2. CH production by all species was best at the slightly alkaline pH which is optimal for growth; it was also dependent on the presence of a large (140-Mda) plasmid. Pre-treatment of bacteria with homologous antisera inhibited CH activity. Various treatments of bacterial cells and RBCs suggested that CH may be a protein molecule, and that a chitotriose-like moiety may serve as CH receptor. RBCs that were incubated with bacteria at 4 degrees C, or with heat-killed bacteria at 37 degrees C, were not lysed; also, isolated cell-surface components (lipopolysaccharide and outer-membrane protein) did not lyse RBCs. This suggests that metabolically active cells are required for CH activity. Production of CH by both EIEC and shigellae is consistent with a common mechanism for the virulence of these organisms.
authors.affiliation: Laboratory Sciences Division, International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh.
authors.forename: K
authors.initials: K
authors.lastname: Haider
authors.forename: M J
authors.initials: MJ
authors.lastname: Albert
authors.forename: A
authors.initials: A
authors.lastname: Hossain
authors.forename: S
authors.initials: S
authors.lastname: Nahar
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D002645:Chickens; D003470:Culture Media; D003967:Diarrhea / Q000378:metabolism / Q000382:microbiology; D004405:Dysentery, Bacillary / Q000378:metabolism / Q000382:microbiology; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000378:metabolism / Q000382:microbiology*; D006168:Guinea Pigs; D000882:Haplorhini; D006460:Hemolysin Proteins / Q000096:biosynthesis*; D006801:Humans; D051379:Mice; D051381:Rats; D012756:Sheep; D012760:Shigella / Q000254:growth & development / Q000378:metabolism / Q000472:pathogenicity*; D012761:Shigella boydii / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D014774:Virulence
chemical_list: D003470:Culture Media; D006460:Hemolysin Proteins