Hemoglobin solutions have been said to consistently increase the lethality of otherwise nonlethal bacterial inocula in experimental models of E. coli peritonitis. We tested the capacity of stroma-free hemoglobin to potentiate the lethality of each of 26 separate clinical isolates of E. coli. The LD50 of each strain with and without stroma-free hemoglobin was then correlated with the ability of that strain to express putative 'virulence characteristics': (1) the expression of 0 (lipopolysaccharide) and K (capsular) antigens, (2) the ability to produce colicin V, (3) the capacity to hemagglutinate mammalian red cells in the presence of 1% mannose, and (4) the ability to secrete α-hemolysin. No perfect correlations were found. The LD50 of only four of the 26 strains of E. coli was affected by hemoglobin. Each of these four strains could hemagglutinate red cells and secreted α-hemolysin. Many other strains whose lethality was not increased by hemoglobin also had these virulence properties. We must conclude that the infection-potentiating effect of hemoglobin cannot be shown for most clinical isolates of E. coli and that the mechanism cannot be correlated with the usual 'virulence characteristics' of E. coli.
|Original language||English (US)|
|Number of pages||7|
|State||Published - 1985|