Open AccessThe effects of Escherichia coli capsule, O‐antigen, host neutrophils, and complement in a rat model of Gram‐negative pneumonia
Author(s) -
Russo Thomas A,
Davidson Bruce A,
CarlinoMacDonald Ulrike B,
Helinski Jadwiga D,
Priore Roger L,
Knight Paul R
Publication year - 2003
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/s0378-1097(03)00636-0
Subject(s) - microbiology and biotechnology , pneumonia , escherichia coli , biology , antigen , virulence , lipopolysaccharide , complement system , immunology , alternative complement pathway , antibody , medicine , gene , biochemistry
Gram‐negative enteric bacilli are agents of life‐threatening pneumonia. The role of the bacterial capsule and O‐antigen moiety of lipopolysaccharide in the pathogenesis of Gram‐negative pneumonia was assessed. In a rat model of pneumonia the LD 50 of a wild‐type extraintestinal pathogenic Escherichia coli strain (CP9) was significantly less than its isogenic derivatives deficient in capsule (CP9.137), O‐antigen (CP921) or both capsule and O‐antigen (CP923) ( P ≤0.003 ). Studies using complement depleted or neutropenic animals established that both neutrophils and complement are important for the pulmonary clearance of E. coli . Data from these studies also support that capsule and O‐antigen serve, at least in part, to counter the complement and neutrophil components of the pulmonary host defense response. Lastly, the contribution of E. coli versus neutrophils in causing lung injury was examined. Findings suggest that E. coli virulence factors and/or non‐neutrophil host factors are more important mediators of lung injury than neutrophils. These findings extend our understanding of Gram‐negative pneumonia and have treatment implications.