Gute Nachricht aus unseren Bergen: Geringe Antibiotikaresistenzen in Escherichia coli Bakterienisolaten ausgewählter Quelleinzugsgebiete der nördlichen Kalkalpen
摘要
The increasing spread of clinically relevant antibiotic-resistant bacteria poses a threat to global health. Clinically relevant resistance is also increasingly found in the environment. Aquatic ecosystems act as potentially important pathways for the spread of these bacteria. This study investigated antibiotic resistance in Escherichia coli populations in two large, extensively farmed Austrian karst spring catchment areas in the Northern Limestone Alps, which also represent groundwater resources for drinking water production. E. coli are not only clinically relevant pathogens but are also used as standard faecal and antibiotic resistance indicators in the environment. E. coli was detected in the spring waters only during the summer months and showed a clear association with the presence of ruminants in the catchment areas, which was confirmed by a correlation with ruminant-associated microbial genetic source tracking markers. By examining a representative sample of 551 E. coli isolates from 13 locations in the two catchment areas, it was possible to show that the prevalence of antibiotic resistance in this study area is low. In 3.4% of the isolates, resistance to one or two classes of antibiotics was observed, and only 0.5% were resistant to three classes of antibiotics. No resistance to critical or reserve antibiotics was detected. A comparison with other studies on antibiotic resistance in alpine karst or spring water highlighted the low level of antibiotic resistance in the catchment areas investigated here, which is most likely due to the high level of protection and careful management of and low use of antibiotics in animal husbandry in the catchment area. The investigation of easily accessible karst springs using a combination of methods comprising (i) standard faecal indicator analysis, (ii) the detection of host-associated genetic microbial source tracking markers, and (iii) the antibiotic resistance analysis of a clinically relevant indicator bacterium, made it possible to obtain a comprehensive overview of the karst spring catchment area with regard to the prevalence and origin of E. coli and its antibiotic resistances. This approach of representative and proactive environmental monitoring is also in line with the planned update of the EU Groundwater Directive. This work was presented at the Mid-Term Symposium 2025 as part of the Vienna Water Resource Systems 2020+ research collaboration and represents a version of the original paper published in the journal Science of the Total Environment in 2023 (Schachner-Gröhs et al.