Quantitative and qualitative studies of Yersinia species in the waste water of a purification plant
Ruhle, C.; Höller, C.; Gundermann, K.O.
Zentralblatt für Hygiene und Umweltmedizin 189(4): 285-299
1990
ISSN/ISBN: 0934-8859 PMID: 2180421 Document Number: 365235
During a long term investigation (October 1986 October 1987) Yersinia spp. were isolated from sewage in 5 different stages of a sewage treatment plant in Kiel (Bülk), Schleswig-Holstein, FRG. Methods applied were MPN-procedure, cold enrichment in CIN-broth and finally incubation on CIN-agar (Cefsulodin-Irgasan-Novobiocin). Yersinia enterocolitica were specified according to their serotypes (O:3/O:9) and biotypes. Results (median/100 ml): sewage influent 90,000 KbE (log 4.95), aerated grit removal tank effluent 14.285 KbE (log 4.15), primary sedimentation tank effluent 20.000 KbE (log 4.30), activated sludge tank effluent 6.000 KbE (log 3.77) and final clarification effluent 260 KbE (log 2.41). After the final clarification a reduction of 99.72% was achieved. A general influence of the outward conditions (water temperature, proportion of oxygen, fecal and total coliforms, water flow, pH) on the behaviour on the Yersinia spp. could not be confirmed. The specification of the 644 germs isolated during the year showed an average proportion of 48.44% Yersinia frederiksenii, 29.5% Yersinia enterocolitica biotype 1, 18.94% Yersinia enterocolitica biotype 2, 2.8% Yersinia intermedia and 0.32% Yersinia kristensenii. Only once a pathogenic Yersinia enterocolitica could be isolated (serotype O:9/biotype 2).