[Occurrence of Salmonella in coastal North Sea water and their hygienic relation to indicator bacteria and sources of contamination].

The quantity of salmonella, fecal coliform bacteria and fecal streptococci was measured in 2003 water samples from North Sea coastal water, drainage canals, the lower River Ems and sewage works. The presence of salmonella did not correlate to an increasing presence of fecal indicator bacteria. In several cases more than 10(3) salmonella per litre were found in samples whose fecal coliform levels met the strictest quality requirements (in accordance with the levels stipulated by EEC bathing water regulations). Additionally 226 marine sediment samples were measured for their content of salmonella only. While salmonella were present in 12.3% of at least 1 litre of the North Sea water samples (bathing places excepted) and in about 7% of sediment samples (10 g), no salmonella were traced in 400 samples from marine water bathing places. The general contamination with salmonella of sea water bathing places can therefore be regarded as low. More frequent occurrences on the beaches must be seen as the result of a concrete case of contamination or other disturbance. The serovarieties of the salmonella isolated from North Sea and Ems waters indicate in comparison with isolations from sewage works, infected humans and calves from the region that the contamination of the local coastal water mainly stems from sewage works and could also on a small scale be caused by sea birds. Salmonella from agricultural sources proved to be irrelevant in this study. Molecular biological examinations of the plasmid profiles for example could give more precise informations. The establishment of serovarieties which are relatively unimportant for human medicine (eg. S. mbandaka) in sewage works, drainage canals and the North Sea reveal the problem involved in evaluating such finds in bathing water samples, because in EEC regulations no differentiation or quantification is made.