Correlation between susceptibility of infants to infections and interaction with neutrophils of Escherichia coli strains causing neonatal and infantile septicemia.

Abstract

The ability of Escherichia coli strains causing invasive infections to associate to human neutrophils and induce oxygen radicals was studied in three groups of blood isolates from neonates and infants: low-virulence septicemia strains (LVS), normal septicemia strains (NS), and meningitis strains (M). Infants were classified by susceptibility to infection as low- (LR) or high-risk (HR). All LVS strains were isolated from HR infants and showed higher association to neutrophils (P < .05) and induced a higher oxidative response (P < .05) compared with that of NS and M strains from LR infants. Three LVS strains caused the cells to release oxidative metabolites extracellularly. Thus, impaired interaction with neutrophils is characteristic of virulent clones of E. coli capable of causing invasive infection in healthy full-term neonates. Furthermore, increased extracellular release of oxygen metabolites could harm the surrounding tissue and potentiate the inflammatory process.