Sensitivity of Shigella strains to the bactericidal activity of human serum. II. Shigella flexneri 3 a is killed by complement activated via the classical pathway, with participation of lysozyme.

Normal human serum is bactericidal for all studied strains (15) of Shigella flexneri serotype 3a. The activity of the serum was similar irrespective of the invasiveness of the bacteria or its lack. The studied bacteria were susceptible to a single mechanism of bactericidal activity involving complement activated via the classical pathway, accompanied by the action of lysozyme.