[Dementia in the very elderly. Results of the Berlin Aging Study]. / Demenz bei Hochbetagten. Ergebnisse der Berliner Altersstudie.

The frequency of dementia in very old subjects, the risk factors and the consequences of the disease were investigated in the Berlin Aging Study in an age- and gender-stratified design (ages 70-103 years, n = 516). Psychiatrists diagnosed a dementia syndrome according to DSM-III-R, applying the GMS-A and HAS interviews. The dementia frequency steeply increases until the 90-94 year group, but there is no further exponential increase for the 95+ group--instead for men the data show a plateau of dementia prevalence. Low education level turned out to be a risk factor, which explains the gender effect in a logistic regression analysis. The apolipoprotein E4 genotype was confirmed as a risk factor--however, only for the older subjects (85+). Dementia was a major reason for institutionalization. The 2-year mortality was no higher in dementia than for age-matched non-demented controls. The results gave a detailed picture of dementia in the very old. This is a prerequisite for planning facilities for psychiatric diagnostics and therapy as well as nursing care.

[Effect of the isolation medium and isolation conditions on the isolation of the bacterial species spectrum in drinking water]. / Einfluss des Isolationsmediums und der Isolationsbedingungen auf die Erfassung des bakteriellen Artenspektrums im Trinkwasser.

With the method of colony-count estimation according to German standards (Trinkwasserverordnung, TVO), bacteria of the genera Aeromonas, Shewanella, Pseudomonas etc. and (if present) representatives of the family Enterobacteriaceae can be detected. Longer incubation and application of low nutrient media enhance the colony counts up to 100-fold, and other bacteria can be isolated, in most cases belonging to the genera Pseudomonas, Alcaligenes, Acinetobacter, Flavobacterium etc.. For the detection of hygienically relevant bacteria (e.g. indicator bacteria) the methods of TVO are sufficient and their routine use is recommended. For further microbiological-ecological studies on the habitat drinking water, the nutrient poor biotope has to be considered and the applied media and methods should be adapted to these requirements.

[Occurrence and incidence of bacteria in the area of drinking water with antagonistic relations to indicator bacteria]. / Vorkommen und Häufigkeit von Bakterien im Trinkwasserbereich mit antagonistischen Eigenschaften gegenüber Indikatorbakterien.

During a period of 8 months about 3000 drinking water samples derived from different water works and distribution systems around the area of the city Bonn were examined for colony count, E. coli and coliform bacteria and bacteria suppressing the growth of E. coli and S. faecalis. A modified agar diffusion test was used for the determination of antagonistic substances. Bacteria which revealed an antagonistic activity were isolated and identified. The majority of water samples (81.9% of the samples examined for antagonistic bacteria against E. coli) contained no bacteria in 1 ml and therefore were not examined for antagonistic substances. Only 2.5% of the samples had bacterial counts greater 100 per ml. In 64.2% of the samples examined for bacteria antagonistic to S. faecalis, no counts were found and 2.4% had counts greater 100. The occurrence of fecal indicators was very low in samples with low colony forming units (cfu). At counts greater than 100 we found E. coli within 30.6% and coliform bacteria in 38.8% of the samples examined for bacteria showing antagonistic activity against E. coli. E. coli and coliform bacteria were determined in 24.2% and 33.3% of the samples examined for antagonistic bacteria against S. faecalis. 20% of the samples with colony counts between 1 to 10 contained bacteria showing antagonistic activity against E. coli and at counts greater than 100 they were found in 57.1% of the samples. On the other hand, the quantity of samples with suppression of S. faecalis was 10 to 20% lower and reached a maximum of 39.4% at cfu greater 100. Most of the isolated antagonistic strains belong to the genus Pseudomonas and even 57.8% of the inhibitory strains against E. coli and 26.5% against S. faecalis were found to be P. fluorescens.

[Microbiology of ground water and drinking water]. / Mikrobiologie des Grund- und Trinkwassers.

Groundwater has been considered a safe source for drinking water protected against surface contamination. However, a number of reports about chemical and microbiological contamination have disproved this assumption. Besides hygienical monitoring, little is known about the microbiology of ground- and drinking water. The purpose of this paper is to give a review about the main fields of investigation concerning microbial activity in ground- and drinking-water-action. The hygienical relevant topics are: survival and transport of microorganisms, microbiological degradation of organic pollutants, turn-over of nitrogen compounds, oxidation and reduction of iron and manganese and development of methods for microbiological water examination.