[Various Salmonella serotypes isolated at a sewage purification plant in a smaller city over a one-year period].

A one-year-study was carried out in the waste-water treatment plant of Plön (population equivalents 60,000), which has a mechanical and a biological purification and an additional chemical flocculation. Samples were taken at five different places in the plant and examined for Salmonella by use of membrane-filtration and MPN-method. 2,611 Salmonella-strains, representing 23 species, were isolated and serologically typed from samples taken at ten days. S. typhi-murium was found most frequently (Table 1, Fig. 1). The largest spectrum of different types was located in the activated sludge-basin and at the outlet of the chemical flocculation (Table 2). No correlation could be established between the qualitative findings and the Salmonella-counts or other parameter like temperatures. All the ten species that have been officially reported to cause salmonellosis in man were also isolated from the sewage (Table 5). Findings of other Salmonella-serotypes are attributed to unreported human infections and animals or other sources.