Observations On The Pathogenic Properties Of The K88, Hly And Ent Plasmids Of Escherichia Coli With Particular Reference To Porcine Diarrhoea

摘要: Summary Strains of Escherichia coli containing different combinations the transmissible plasmids governing production α-haemolysin (Hly), enterotoxin (Ent) and K88 antigen (K88) were prepared by selective addition or removal these tested for ability to produce diarrhoea when given orally naturally reared piglets recently weaned pigs. The plasmid from an O141:K85ab,88ab strain was accompanied loss its diarrhoea-producing capacity. It restored introducing a another E. coli. The Hly had no observable effect. Neither did wild enteropathogenic antigenic formula O141:K85ac; Hly- form this strain, like Hly+ form, produced oedema disease in diarrhoea. As consequence receiving Ent plasmid, non-haemolytic O8:K40, 88ab:H9 more frequently severely than hitherto; after it became non-enteropathogenic. A non-pathogenic O9:K36:H19 rendered introduction plasmids. K88+ Ent+ moderately severe piglets. A smaller proportion those Ent- developed milder diarrhoea. K88- forms ill-effect. Bacteriological examinations on animals O141:K85ab,88ab, O8:K40,88ab:H9 strains revealed that enabled organisms proliferate high up small intestine, essential prerequisite pathogenesis appeared play part proliferation, only followed. The into usually increase virulence mice challenged intraperitoneally, extent varying according particular introduced. Virulence not related directly haemolytic activity. K88+ less virulent intraperitoneal injection corresponding forms. So Salmonella typhimurium S. choleraesuis oral infection; able survive alimentary tract tissues ones. also pigs form.