A Current Update on Avian Pathogenic Escherichia coli

Avian Pathogenic Escherichia coli (APEC) is a major cause of colibacillosis and extraintestinal diseases in chickens, turkey and other avian species, which result in decreased feed conversion efficiency and significant flock mortality. Severe infections and fatality of birds occur depending on the virulence of the infecting APEC strain, host immune status, and other predisposing factors. The disease is characterized by a diverse array of lesions, including aerosacculitis, pericarditis, perihepatitis, peritonitis, polyserositis, and septicemia. APEC employs virulence factors such as adhesins, iron acquisition systems, toxins, increased serum survival protein, hemolysins, lipopolysaccharide, capsule, and colicin production for its pathogenesis in birds. Although antibiotic therapy is widely used in the poultry industry for controlling APEC, emerging APEC resistance to multiple antibiotics is a concern. APEC isolates obtained from infected poultry have been reported to exhibit resistance to a wide range of antimicrobials, including tetracycline, oxytetracycline, streptomycin, gentamicin and sulfonamide. Additionally, acquired resistance to these antimicrobial agents increasingly complicates the management of APEC infection. Another growing concern is that some APEC strains are similar to human drug resistant Escherichia coli, and poultry products may transmit antimicrobial drug - resistant E. coli to humans. This chapter presents a comprehensive review of the current problems associated with APEC-infections in poultry with an emphasis on APEC’s increasing antibiotic resistance, and potential strategies for controlling colibacillosis in poultry. Moreover, its public health significance in humans is discussed.