Bactericidal activity of normal human serum against Morganella, Proteus, and Providencia strains

: The susceptibility od Proteus, Providencia, and Morganella strains to bactericidal action of human serum was examined. The percentage of survival was determined after one and three hours incubation with 50% human serum. The susceptible strains were treated by serum preparations with blocked classical or alternative complement activation pathways as well as with lysozyme removed. Following mechanisms of the bactericidal action of serum were found: complement activated by the classical or alternative pathway with participation of lysozyme, complement activated simultaneously via both pathways-while the participation of lysozyme was necessary for killing some strains and superfluos for others and complement activated only via the classical pathway without lysozyme.