Non-Association of Macrophage Phagocytosis and Oxidant Stimulation with Complement Resistance and Colicin V Production by Avian Escherichia coli

Abstract

Avian isolates of Escherichia coli were classified as virulent based on their isolation from chickens with natural cases of colisepticemia, production of colicin V, and complement resistance. A second group of isolates was designated as avirulent based on their isolation from healthy chickens, their inability to produce colicin, and their classification as sensitive or intermediate to the action of complement. In vitro assays of phagocytosis and oxidant production were performed in an attempt to correlate these activities with the ability of each group of bacteria to escape the specific host defense mechanisms of phagocytosis and killing. Although oxidant production regressed with significant linearity on percent phagocytosis, neither group (virulent or avirulent) differed in ability to stimulate peritoneal macrophage phagocytic and oxidant activity when opsonized with normal chicken serum. These results differ from those in mammalian species.