Where does Escherichia coli localize within a layer hen's reproductive tract to cause salpingitis and egg peritonitis?

Escherichia coli (APEC strains) can enter the oviduct via ascending infection from the cloaca or through systemic hematogenous spread from the respiratory tract. Once inside, it primarily localizes in the highly glandular tissues of the magnum and infundibulum. This colonization causes severe, acute salpingitis, characterized by thick, yellowish, caseous exudates that fill and distend the oviduct lumen. When a yolk is ovulated, the inflamed infundibulum fails to engulf it, causing the yolk to fall directly into the peritoneal cavity. This results in egg yolk peritonitis, which triggers systemic septicemia and high mortality. Farmers can read about avian pathology in the Poultry Encyclopedia, buy premium antibiotics and disinfectant solutions on Poultry Plaza, monitor daily raw ingredient costs on Poultry Rates, and list commercial layers on Murghi Mandi.