Abstract
Avian pathogenic Escherichia coli (APEC) is one of the extra intestinal pathogenic E. coli (ExPEC). Previous studies showed that O1, O2 and O78 serotypes are mostly associated with Colibacillosis outbreaks, but recently there are emergent new pathogenic serotypes that have spread worldwide. Wide antigenic diversity exists among APEC strains in Egypt; however, the involvement of a particular O serotype in the infection process appears to vary with the geographical region. Different virulence genes have been identified in APEC. Recently; the presence of these virulence genes is being employed as an indication of pathogenicity, rather than the tedious E. coli serotyping methods. In Egypt; several virulence genes were studied, and were found to be different based on the geographical area. However; all studies were limited to a small number of screened virulence genes, in addition to the inconsistency of these screened genes. To control APEC, antibiotics have been used for decades; however the emergence of multi-drug resistant E. coli, and the difficulty of discovering new antimicrobial therapies made vaccine the best choice to control E. coli infections in poultry farms. In this review, the various aspects of APEC infection in poultry with special focus on the epidemiology of APEC in Egypt in relation to virulence traits were discussed. In addition, the most recent vaccination trials against the APEC diseases in poultry were discussed. We concluded that the virulence gene patterns of APEC can be considered as molecular markers of pathogenicity. Although of their current limitations, some vaccine trials showed promising results as good alternative to control colibacillosis in poultry.
Highlights
E. coli is a Gram-negative, rod-shaped, facultative anaerobic bacterium of the Enterobacteriaceae family.It colonizes the intestinal tract of mammals and birds (Bélanger et al, 2011)
Currently; we review the various aspects of avian pathogenic E. coli (APEC) infections in poultry, with special focus on the epidemiology of APEC in Egypt in relation to virulence traits
Younis et al, (2017); El-Sawah et al, (2018) studies showed that wide antigenic diversity existed among avian pathogenic E. coli strains in Egypt, and worldwide
Summary
E. coli is a Gram-negative, rod-shaped, facultative anaerobic bacterium of the Enterobacteriaceae family It colonizes the intestinal tract of mammals and birds (Bélanger et al, 2011). Previous study of Russo and Johnson, (2000) identified several traits for distinguishing the three pathotypes of ExPEC including; avian pathogenic E. coli (APEC), neonatal meningitis E. coli (NMEC), and uropathogenic E. coli (UPEC). Colibacillosis in poultry includes systemic and localized infections. Extrinsic factors involve environment; exposure to other infections, virulence, duration and levels of exposure, whereas intrinsic factors involve age; route of exposure, passive and active immune status, in addition to strain and breed of chickens. Younis et al, (2017); El-Sawah et al, (2018) studies showed that wide antigenic diversity existed among avian pathogenic E. coli strains in Egypt, and worldwide. The involvement of a particular O serotype in the infection process appeared to vary according to the geographical region (Table 1)
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