Enterococciwere detected occasionally in 100 L samples ofwater abstracted froma shallowaquifer in a natural dune infiltration area for drinking water production. Enterococcus moraviensis was the species most frequently identified in these samples. Because there are no existing reports of faecal sources of E. moraviensis and the closely related E. hemoperoxidus, this study aimed to find such sources of these two species in the dunes. Faecal samples from various animal species living in the vicinity of abstraction wells, were analysed for enterococci on Slanetz and Bartley Agar. From these samples, enterococci isolates (1,386 in total) were subsequently identified using matrix assisted laser desorption ionizationtimeof flight (MALDI-TOF)mass spectrometry. E.moraviensiswas found in the faeces of geese, foxes and rabbits. Also, E. haemoperoxidus was isolated from goose faeces. Using hierarchical clustering, the species composition of Enterococcus spp. isolated from abstracted water formed one cluster with the species composition found in geese droppings. A sanitary survey supported the indication that feral geese may provide a substantial faecal load in particular parts of this dune infiltration area, close to the water abstraction system. This study confirms the faecal origin of E.moraviensis and E. haemoperoxidus from specific animals, which strengthens their significance as faecal indicators.

Soil passage through sand dunes has previously been shown to remove enteric micro-organisms very effectively, and hence is used for the production of drinking water. However, enterococci have occasionally been isolated from abstracted water (after dune passage) in one of the dune infiltration areas in the Netherlands. Enterococcus moraviensis was the most frequently isolated species. Until now, no faecal sources of this species have been reported and the potential for growth under certain environmental conditions was reported for other Enterococcus species. The aim of this study was to determine the ability of E. moraviensis to grow in habitats present in the dune passage process (dune vegetation, sediment from abstraction wells, biofilm developed using abstracted water and soil). Different concentrations of boiled and filtered (0.45 μ m) plant extracts obtained from dune vegetation supported growth (up to 6 log), with maximum concentrations after 4 to 6 days at 15 °C. Although E. moraviensis was shown to be able to attach to the biofilm, no growth was observed in biofilm or in sediment and soil. These observations confound the use of E. moraviensis as a faecal indicator.

The emergence of clinical enterococcal isolates that are resistant to both ampicillin and vancomycin is a cause of great concern, as therapeutic alternatives for the treatment of infections caused by such organisms are becoming limited. Aquatic environments could play a role in the dissemination of antibiotic resistant enterococci. This study investigated the presence of ampicillin and vancomycin resistant enterococci in the treated effluent of six wastewater treatment plants (WWTPs) and in surface water used as a source for drinking water production in the Netherlands. Membrane filtration in combination with selective media with ampicillin or vancomycin was applied to determine the presence of ampicillin resistant Enterococcus (ARE) and vancomycin resistant Enterococcus (VRE) species. Ampicillin resistant Enterococcus faecium (minimal inhibitory concentration (MIC) >16 μg/mL; n = 1033) was observed in all studied WWTP effluents. In surface water used for drinking water production (intake locations), no ARE or VRE were observed. At both types of location, intrinsic vancomycin resistant Pediococcus spp., Leuconostoc spp. and Lactobacillus spp. were isolated with the vancomycin medium. The ampicillin resistant E. faecium (AREfm) isolates (n = 113) did not contain the vanA or vanB gene, but MIC testing for vancomycin showed intermediate vancomycin resistance (2-8 μg mL^-1) to occur in these AREfm strains. This study documents the discharge of ampicillin resistant E. faecium strains with intermediate vancomycin resistance by the WWTPs into the surface water, but no presence of these strains downstream at intake locations for drinking water production.