Avian Pathogenic Escherichia coli in Audouin gulls (Larus audouinii). Could they affect the surviving of the bird colonies?

A total of 39 E. coli strains isolated from cloacal swabs and unhatched eggs of Audouin’s gulls (Larus audouinii) living the Salento coast (Italy) were serotyped and molecular characterized for the presence of irp2, fyuA, tsh, papC, fimC, iucD, and eae genes described for Avian Pathogenic E. coli (APEC). Eight different serogroups (O1, 06, 08, 015, 075, 0139, 0146, 0147) were distinguished: we recorded a very high rate of untypeable strains. Genotyping by PCR achieved to detect fimC and irp2, described for APEC strains, as most predominant genes circulating in the gulls population, accounting for 94.87% and 97.43% respectively. Nevertheless, a significant co-existance of virulence genes was demonstrated to belong to E.coli of eggs origin. Particularly, fimC/tsh/iucD pathotype, recognized as most responsible of illness in poultry,emerged in 8.69% of E. coli of eggs origin.