Avian colibacillosis, any infection, localized or systemic, caused by avian pathogenic Escherichia coli (APEC), is the most common infectious disease in the poultry industry. APEC is an extraintestinal pathogen that generates fibrinous lesions, especially in visceral organs. APEC infections also manifest in a wide range of symptoms including omphalitis and yolk sac infection, cellulitis, swollen head syndrome in a localized form, colisepticemia, chronic respiratory infection, and others. APEC infections are responsible for large economic losses attributable to low productivity, mortality, and seizures during slaughter.