Evaluation of enteromicroflora of common crane (Grus grus) as a potential reservoir of bacterial antimicrobial resistance

Migratory birds could be important vectors of pathogenic bacteria and antimicrobial resistance transmissions over long distances. The common crane (Grus grus) is one of the largest migratory birds in Europe which form numerous flocks during migration. The aim of the study was to analyse enteromicroflora of common crane and to analyse the occurrence of antibiotic resistant bacteria in faecal samples of common crane collected at the most important migration stopover site of this bird species in Slovakia, the Special Protection Area Senianske rybniky. Upon cultivation on selective media 182 bacterial isolates were identified by MALDI-TOF mass spectrometry and analysed for antibiotic resistance. The most prevalent species of enterococci in faeces of common crane was Enterococcus casseliflavus (80.2%). Among Enterobaceriaceae isolates the most frequently detected species was Escherichia coli (51.5%) followed byPantoea agglomerans (20.8%) and Serratia liquefaciens (19.8%). Very low frequency of antibiotic resistant bacteria was detected in faeces of common crane during the three years research period. No antimicrobial resistance was detected in enterococci and a single ampicillin resistant Raoultella ornithinolytica isolate, carrying the blaKPC gene, was detected among enterobacteria. Our results suggest that contamination by common crane faeces represents minimal risk in terms of the spread of antimicrobial resistance in the environment. The presence of some pathogenic bacteria requires further investigation of the risk associated with the transmission of bacteria during migration of cranes.