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Biomedical subjects

D Schoenen

Publications and source records attributed to D Schoenen.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Microbial contamination of water by pipe and tube materials. 3. Behavior of E. coli, Citrobacter freundii and Klebsiella pneumoniae].

Materials water comes into contact with can promote the microbial growth as it could be shown before. The reaction of an unspecific microorganism flora and of Legionella pneumophila in pipes and hoses has been described in the two previous communications. The investigation with L. pneumophila has shown that even a pathogen organism can grow upon the materials. Therefore it was of special interest to prove whether indicator organisms for the testing of drinking water can grow in pipes and hoses as well. Escherichia coli, Citrobacter freundii and Klebsiella pneumoniae grew after the experimental contamination for many weeks on the rubber hose until the test was finally stopped, in the other pipes and hoses (glass, high-grade steel, PVC, PE, PA, PTFE and silicone) E. coli could be found for maximal 7 weeks, Citrobacter freundii for 1 week and Klebsiella pneumoniae for maximal 3 weeks. In the copper pipe the organisms could be found only for a few days.

Citrobacter↗
PubMed1988

[Pseudomonas aeruginosa contamination of disinfectant solutions from central disinfectant dispensing devices in swimming pools].

The disinfectant solutions from central dosing operators in swimming-bathes were microbiologically tested. The disinfectant solutions in all but one of the tested swimming-bathes showed a microbial colonization. The number of colonies ranged to 3 X 10(5) Col/ml and in 11 of the 24 tested bathes Pseudomonas aeruginosa could be isolated from the disinfectant solutions. Especially the occurrence of P. aeruginosa is quite unfavourable. Due to the results special restorations seem to be necessary.

Disinfectants↗
PubMed1988

[Microbial contamination of water by pipe and hose material. 1. Detection of colony count changes].

Materials may produce a growth of microorganisms by contact with water. Pipes and hoses with a narrow diameter have not yet been tested on their influence on the microbial colonization of the water. A harmful change has been discussed especially in dental treatment units. Pipes and hoses were tested in their influence on the microbial growth for half a year. Glass, high grade steel, copper and PTFE showed no increase in microorganisms or only a little in the beginning. The other tested materials, PVC, PE, PA, silicon and rubber, produced an intensive microbial growth.

Bacteria↗
PubMed1988

[Microbial contamination of water by pipe and tubing material. 2. Growth of Legionella pneumophila].

In the 1st communication it was possible to show that some hoses and insufficiently cleaned high grade steel pipe can produce a microbial growth. The growth-promoting effect of materials in the water distribution system for Legionella pneumophila has been discussed before. In this investigation it was tested how L. pneumophila behaves in pipes and hoses with narrow diameter, at temperatures from 35 degrees C to 40 degrees C and over a time of half a year. L. pneumophila could be found in high numbers in the water from PVC, PE, PTFE, rubber and silicon hoses all over the time and regularly in low numbers or occasionally in glass, high-grade steel pipes and PA hose. L. pneumophila could be found only for the first 4 weeks in the copper pipe.

Copper↗
PubMed1987

Microbiological evaluation of drinking water construction materials--comparison of two test procedures.

Materials used in contact with drinking water can impair water quality by supporting the growth of aquatic microorganisms. In order to prevent this problem several different test procedures have been developed but to date no comparative study of the performance of these methods has been published. During collaborative studies between the regional laboratories of the Thames Water Authority, London, and the Institute of Hygiene, University Bonn, duplicate samples of 11 PVC materials were exchanged and evaluated by the standard methods used in the United Kingdom (UK) and the Federal Republic of Germany (FRG). There was a good agreement between the results as assessed by the published criteria. When a stricter criterion for interpreting the results of the UK method was applied to the findings, a complete agreement between the methods was observed.

Bacteria↗
PubMed1987

[Increase in the colony count in drinking water tanks caused by solvents from the coating material].

As a freshly coated storage tank was put into operation a permanent colony increase in the drinking water (up to 7400 cfu/ml) could be detected. By chlorine dosage (30 mg/l) colony counts were reduced. From a second storage tank which had been coated at the same time bituminous coating material and air samples could be taken. After the exposure of the bituminous coating material in aqua bidest. 48 organic compounds were found by GC/MS-analysis. The main compounds were xylene, ethylbenzene and 1,2,4-trimethylbenzene. These compounds were also found by GC-investigations of the air-samples. The dependence between the used organic solvents and the colony increase could be demonstrated by biodegradation tests of solvent compounds. It was found that about 50 per cent of the identified compounds could be degraded by microorganisms and therefore caused a colony increase in drinking water.

Bacteriological Techniques↗
PubMed1986

[Decontamination of drinking water taps colonized with Pseudomonas aeruginosa].

Water taps in hospitals are quite often contaminated with Pseudomonas aeruginosa. It is possible that Pseudomonas aeruginosa is disseminated with the water. It seems necessary to disinfect the water taps in order to prevent an endangering of the patients and a contamination of wetted areas. It has been looked for a method of decontamination which could be used under practical conditions. The experimentally contaminated taps could be disinfected in a short time when hot water was lead into the taps. The taps could not be disinfected by heating with a flexible electric heating ribbon.

Disinfection↗
PubMed1986

[Recent studies on the recolonization of drinking water].

About the re- or aftergrowth in drinking water there are some reports. But there are still no real ideas about the reasons and the colony counts to which the water may rise under practical conditions when there is no external influence. In these investigations drinking water was stored in a reservoir for 3-6 weeks and the increase of colonies was observed. In all six tests there was an increase in the colony count. The maximum counts fluctuated between 8-2000 colonies/ml. The water, a mixture of surface- and groundwater, had not a homogeneous tendency of re- or aftergrowth. The chemical parameters gave no indications to these differences.

Bacteria↗
PubMed1985

[Microbial colonization of coating and building materials in contact with drinking water. 11. Long-term studies of a drinking water reservoir with polyester isolation].

Building materials of drinking water reservoirs can support a microbial growth as shown in former communications. A new case is presented, where the microorganisms used the polyester isolation as carbon source. The isolation was installed between two concrete layers of a drinking water reservoir. The organic substances were identified by chemical analyses.

Bacteria↗
PubMed1985

[Qualitative and quantitative determination of bacterial populations in an aquatic environment. 7. Development of bacterial growth on raw materials exposed to potable water].

Refined steel plates coated with different materials that contained available organic compounds led to a microbial growth on the surface. Even plastics and bitumen which were used in the sphere of drinking water showed after an exposure time of three months up to 192 ml slime per square meter. The number of viable bacteria within the Aufwuchs was in the range of 10(7) cfu/ml. The production of slime increased with time. The relation of carbohydrate and protein content significantly changed from 2 at the beginning to 30 after 12 months of incubation the bitumen coating test plates. This indicates an increase synthesis of carbohydrate containing extracellular polymeric substances during the late phase of growth. The bacteria isolated from the Aufwuchs mainly belonged to the genera Pseudomonas, Flavobacterium, Acinetobacter, Caulobacter, sheated bacteria and other gramnegative physiologically nonreactiv roads. During exposure of the plates the relation changed within the bacterial communities of the main groups. Comparing the bacteria communities of inlet and outflow water it became evident that the later one was influenced by bacteria of the Aufwuchs.

Bacteria↗
PubMed1984

[Determination of material-dependent germ multiplication in the stand test].

Materials used in drinking water may lead to an increase of microorganisms. Microbiological examinations of material in jar tests have been repeatedly dealt with in literature. However they yielded contradictory results. Within the scope of these examinations it was to be found out if and under which conditions an experimental examination of materials, the criterion of test being microbial growth in water, is possible. For the examinations in jar tests it is necessary to have a minimal concentration of mineral salt in the water and to use germs which can degrade the components issued by the materials.

Acetates↗
PubMed1982

[Microbial colonization of moistered bitumen and high-grade steel plaids revealed by scanning electron micrographs].

There have been some reports about the increase of colonic counts and microbial growth on the surface of materials in the sphere of tap water. But there have been no hints about the development of the initial colonization with microorganisms from the water to a growth on the surface. The development of a microbial community on high-grade steel or solvent containing bitumen was revealed in a comparative study by scanning electron microscopy. There was hardly any increase in the count of bacteria on high-grade steel during the four weeks exposition. On bitumen there was a dense and multilayered growth with bacteria. Already within one week the number of bacteria on bitumen was much higher than on high-grade steel.

Alloys↗
PubMed1982

[Microbial colonization of lining materials and building materials in the drinking water supply. 10. The behavior of a polyamide pipe in use and under laboratory conditions].

After the installation of a new rising-pipe the count of bacteria in the water of a well increased temporarily. After a working period of 25 months the pipe was removed and microbiologically examined. On the inside and the outside of the pipe surface microbial growth could be observed. After the first increase of colony count in the water a comparable polyamid-pipe was tested microbiologically under laboratory conditions. In this case growth on the surface could also be found at 3 successive inspections.

Bacteria↗
PubMed1981

[Microbial settlement of paint- and building-materials in the sphere of drinking water. 7. Communication: long time observations in two drinking water reservoirs coated by epoxy resin (author's transl)].

In two potable water reservoirs with an epoxy resin lining an increase of the colony count in the water and a visible microbial growth on the surface could be observed. The slime consists of bacteria and fungi. In one case higher organisms like protozoa were found too. The growth of microorganisms is caused by organic compounds of the epoxy resin which can be deteriorated by microorganisms. After a period of 3 years both materials still promote microbial growth on the surface.

Animals↗
PubMed1981

[Microbial settlement of paint- and building-materials in the sphere of drinking water. 8. Communication: Experimental examination of epoxy resin in laboratory tests (author's transl)].

Different observations in potable water reservoirs with epoxy resins induced us to investigate some paintings. Commercial products of known and unknown constituents were tested. Some commercial products recommended for the use in potable water sphere produced microbial slime while others didn't. Solvents, accelerators and even both of the building compounds of the epoxy resin, if they are not used in the stoichiometric mixing ratio, may produce microbial slime. The temperature of preparation has an important influence on the slime formation.

Bacteria↗