title: Virulence of Escherichia coli strains with R-plasmid mediated penicillin resistance in mice infections.
abstract: Penicillinase I-, II- and III-producing R-plasmid of Escherichia coli were transferred to Escherichia coli 177, KC-14, and 444. These strains are highly virulent in mice. This study was conducted to investigate the influence of conjugative R-plasmid on the virulence of its host strains. Escherichia coli 177 after penicillinase I- or III-producing R-plasmids transfer retained parental levels of virulence. On the other hand, penicillinase II-producing transconjugants showed reduced virulence in mice. The virulence of its revertants, in which R-plasmid was eliminated by heat, were equivalent to that of the host strain. It is suggested that the decrease in the virulence of transconjugants was not due to transferred R-plasmid. The reduced virulence of the these transconjugants may be due to alterations in their components such as the lipopolysaccharides in the cell envelope.
authors.affiliation: Department of Microbiology, Kyoto Pharmaceutical University.
authors.forename: Y
authors.initials: Y
authors.lastname: Obana
authors.forename: T
authors.initials: T
authors.lastname: Nishino
mesh_terms: D000818:Animals; D003227:Conjugation, Genetic; D004926:Escherichia coli / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000382:microbiology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010403:Penicillin Resistance / Q000235:genetics*; D011815:R Factors / Q000235:genetics*; D014774:Virulence