Thesis (Ph.D.) - Cairo University - Faculty of veterinary medicine - Department of Zoonoses

Wild birds are essential for public health because they can carry a variety of pathogens such as E. coli and Salmonella species that are transmissible to people. As a result, the current study was carried out to determine the probable role of migrating ducks and quails in the spread of these infections in Damietta Governorate and neighboring cities. A total number of 349 (209 ducks and 140 quails) and 496 (197 ducks and 299 quails) migratory bird cloacal swabs were collected for the detection of Shiga toxin {u2013}producing Escherichia coli (STEC) and Salmonella spp. respectively. For isolation and identification of these pathogens, the samples were cultivated on STEC CHROMagar and X.L.D medium, and then routine bacteriological assays such as Gram's stain and conventional biochemical testing were performed. Molecular approach used to detect the stx1, stx2, and eae genes in STEC isolates, as well as the stn, invA, and spvC genes in Salmonella isolates. Antimicrobial sensitivity testing of the identified STEC serotypes revealed that O125 was resistant to ampicillin, ceftriaxone, meropenem, azithromycin, and chloramphenicol, whereas O86 was resistant to ampicillin, ceftazidime, ceftriaxone, cefepime, meropenem, and chloramphenicol. Both STEC and Salmonella positive isolates were sequenced. Two STEC isolates were found in the studied birds, with an overall occurrence of 0.57 percent (2/349), one from migrating quail with the stx2 gene serotyped as O125 and the other from common teal duck (Anas cercca) with the stx1 gene serotyped as O86. While three Salmonella isolates with a prevalence of 0.6 percent were found, these strains were obtained only from Northern Pintail ducks (Anas acuta). The results of phylogenetic tree analysis revealed that STEC gene sequences and spvC gene sequences have a high genetic relatedness with human isolates from various countries, indicating that each species crossed paths during migration. In conclusion, this study sheds insight on the potential role of migrating birds in the transmission of numerous exotic bacterial strains throughout their movement

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