Abstract: Avian pathogenic Escherichia coli (APEC) is a significant threat that affect domesticated and wild birds. Studies related to the prevalence of APEC in the migratory and wild birds are relatively few compared with those related to other avian species. In particular, the role of the little white egret (Egretta garzetta) as a carrier and a reservoir for transmission of the APEC to other avian species had been neglected. Therefore, this work was done to study the occurrence of multidrug-resistant (MDR) APEC in the extraintestinal tissues of the little white egret. The overall isolation percentage of APEC was 20%. The highest isolation percentage was recorded in lungs followed by air sacs, heart blood, liver, and kidneys with percentages of 20%, 15%, 10%, 10%, and 5%, respectively. Sereotyping of E. coli isolates revealed, 4 (33.33%) strains of O26:K6, 3 (25%) strains of O78:K80, 2 (16.66%) strains of O114:K90, 2 (16.66%) strains of O2:K1, and 1(8.33%) strain of O127:K63. Virulence-associated genes including arginine succinyltransferase (astA), temperature sensitive hemagglutinin (tsh), putative avian hemolysin (hlyF), and iron outer membrane receptor (iroN) were screened using polymerase chain reaction (PCR) and all of tested genes were detected in E. coli serotype O78:K80. All E. coli isolates showed drug resistance to at least one of the 12 antimicrobials tested, with remarkable high resistance (100%) to ampicillin, nalidixic acid, and penicillin. In conclusion, the little white egret should be considered as a potential carrier for MDR APEC.

Key words: E. coli; little white egret; multidrug resistance; virulence attributes


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