Monitoring non-wild type antibiotic resistant Enterobacteriaceae in the River Danube: a six-year-comparison

Abstract

Human induced antibiotic resistant bacteria (ARB) are not only found in clinical surroundings: large rivers are of great concern as regards their spreading. This ongoing study´s aim is to analyse the major propagation pathways and sources of ARB in the Danube, and to compare the results with data obtained in 2013. Escherichia coli and Klebsiella spp. isolated during the 4th Joint Danube Survey were tested for their antibiotic susceptibility. 23.2% of 1635 E. coli were resistant and 11.7% were multiresistant. There was a significant increase in resistances to augmentin, moxifloxacin and piperacillin/tazobactam and a significant decrease regarding tetracycline. 23 expressed an extended-spectrum-beta-lactamase phenotype. 15.87 % of 630 Klebsiella spp. were resistant and 0.95% were multiresistant. Resistances to moxifloxacin and augmentin were the most common resistances detected. Two isolates showed an ESBL-phenotype, and two isolates were resistant to the last line antibiotic tigecycline. In comparison the data of 2013 and 2019 show a similar proportion for multiresistant E. coli, but regarding resistances to some single antibiotics significant changes were determined. In contrast, the Klebsiella isolates showed a very similar distribution of resistances. Despite, 30% of non-wild type resistant E. coli in the environment is a very high number when compared to clinical settings with approximately 50%. However, the relevance of these findings concerning human health and the environment is yet unclear as there is only a very limited number of studies for comparison and studies on the significance of pathways from the river back to humans are largely missing.