Introduction: The natural ability of bacteria to develop resistance has been accelerated by the selective pressure exerted by the improper and increased use of antibiotics in human therapy. Wastewater systems, especially those receiving hospital or livestock wastewater, were demonstrated to be significant sources of significant epidemic pathogens such as Klebsiella pneumoniae or Pseudomonas aeruginosa.

Goals: The aim of the study was to examine if clinically relevant multi-drug resistant pathogens occur in bathing waters in Schleswig-Holstein and if these are associated with the discharge of hospital wastewater. If necessary, updated recommendations for action and measures should be developped.

Methods: The following monitoring sites were included: hospital wastewater (collection chamber), influents and effluents from sewage treatment plants and bathing waters with discharge of treated wastewater. Focus was placed on multi-drug resistant gram-negative rods with carbapeneme resistance (4MRGN), which are spread into the environment through discharge into water/hospital wastewater: Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae and Klebsiella oxytoca. cultivation was carried out on selective culture media with species identification. Confirmed isolates were further examined using a Vitec antibiogram and, if necessary, an E-test and/or carbapenemase test. The results were interpreted according to EUCAST criteria.

Results: We did not detectany multi-drug resistant gram-negative rods with carbapeneme resistance in the bathing water samples tested. Only one isolate of multi-drug resistant Klebsiella pneumoniae (3MRGN) was detected in a bathing water sample.

Conclusions: In our analysis we did not detect multi-drug resistant gram negative rods with carbapeneme resistance in bathing waters. Thus, lacking an acute health risk for the general population there is no need to change routine testing and parameters for bathing waters in Schleswig-Holstein.