Bacterial self-defence: How Escherichia coli evades serum killing

Abstract

The ability to survive the bactericidal action of serum is advantageous to extraintestinal pathogenic Escherichia coli that gain access to the bloodstream. Evasion of the innate defences present in serum, including complement and antimicrobial peptides, involves multiple factors. Serum resistance mechanisms utilized by E. coli include the production of protective extracellular polysaccharide capsules and expression of factors that inhibit or interfere with the complement cascade. Recent studies have also highlighted the importance of structural integrity of the cell envelope in serum survival. These survival strategies are outlined in this review with particular attention to novel findings and recent insights into well-established resistance mechanisms. Some Escherichia coli isolates can survive in the bloodstream as they possess factors that evade killing by serum proteins. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.