Role of lipopolysaccharide and capsule in the serum resistance of bacteremic strains of escherichia coli

Alan S. Cross, Kwang Sik Kim, D. Craig Wright, Jerald C. Sadoff, Peter Gemski, Alan S. Cross, Kwang Sik Kim, D. Craig Wright, Jerald C. Sadoff, Peter Gemski

Research output: Contribution to journalArticlepeer-review

Abstract

To define the relative roles of capsule and lipopolysaccharide in the virulence of Escherichia coli obtained from blood, we compared the behavior of Kl- and K5-encapsulated strains in serum bactericidal and rat virulence assays. Unencapsulated isogenic mutants selected from five parent strains of E. coli O12:K1, but not of 018:K1 or 07:K1 (all rough- specific phage insensitive), were lysed by normal human sera. In contrast, isogenic mutants from strains of serotypes 06:K5 and 018:K5 retained the serum resistance of the parent strains. There was a >105 difference in LD50 in newborn rats between Kl-positive and Kl-negative pairs of E. coli serotypes 018 and 07 and a >1 log difference between isogenic pairs of serotype 012; however, the K5 isogenic pairs had a similar LD50. Some non-06 O serotypes, however, required the K5 capsule for serum resistance. We conclude that some O serotypes require encapsulation for optimal virulence but that other O serotypes may not.

Original languageEnglish (US)
Pages (from-to)497-503
Number of pages7
JournalJournal of Infectious Diseases
Volume154
Issue number3
DOIs
StatePublished - Sep 1986
Externally publishedYes

ASJC Scopus subject areas

  • Immunology and Allergy
  • Infectious Diseases

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