White‑tailed eagles (Haliaeetus albicilla) in protected Danube wetlands as carriers of Escherichia coli with resistance and virulence genes

Abstract

Environmental pollution with antibiotics and antibiotic resistant bacteria represents a significant ecological problem around the world. In this study, we wanted to identify multiple clinically important genotypes of Escherichia coli (E. coli) in one of the largest populations of white-tailed eagles (Haliaeetus albicilla–H. albicilla) nesting in the protected area of Danube floodplains. This is the first such study of the species, covering the nesting community (20 of 21 active nests) of H. albicilla in one nature reserve. High resistance to fluoroquinolone was detected in one multidrug-resistant E. coli isolate, and this type of resistance was induced by the mutations on topoisomerase genes gyrA, parC, and parE. This isolate also carried resistance genes sul1 and tetB and the virulence gene iutA. Molecular typing by randomly amplified polymorphic DNA (RAPD) in combination with phylogenetic typing revealed high diversity among 11 E. coli isolates. With five different replicon types found (IncFIB, IncFIA, Inc FIC, IncY, and IncI1), the majority of isolates had multi-replicon status with a pronounced capacity of horizontal transfer of resistance and virulence genes. The coexistence of at least two virulence genes linked to development of a pathogenic phenotype and multi-replicon status in three E. coli isolates implies the potential for causing extra-intestinal infections, as well as horizontal transfer of pathogenic genetic determinants in the bacterial community. Resistance to synthetic antibiotics such as fluoroquinolones in an E. coli isolate from white-tailed eagle clearly points to the indirect anthropogenic sources of antibiotic pollution and antibiotic resistant bacteria present in wildlife food chains.