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Biomedical subjects

R H Schubert

Publications and source records attributed to R H Schubert.

At least 19 recordsLinked to original sources
PubMed2000

Intestinal cell adhesion and maximum growth temperature of psychrotrophic aeromonads from surface water.

Investigation of 650 Aeromonas strains taken from surface water--used as a source of drinking water--and from the associated drinking water treatment plants has demonstrated that only a small proportion of the strains are endowed with intestinal cell adhesion and growth at 39 degrees C; these characteristics are concurrently encountered in Aeromonas strains from clinical material. The investigations permit the conclusion that even the Aeromonas species, of which certain strains are pathogenic to human, cannot generally be viewed as being potentially pathogenic.

Aeromonas↗
PubMed1999

Cell adhesion of Plesiomonas shigelloides.

Plesiomonas shigelloides evidences an inconsistent behaviour in the INT-407 cell adhesion test. Isolates from clinical material evidence regular and pronounced cell adhesion which, however, is low compared with that of clinical Aeromonas isolates. In some of the P. shigelloides strains isolated from clinical material, the cell adhesion is markedly more pronounced than in others. The P. shigelloides strains isolated from the natural habitat from both pond water, mud samples and water insects manifest either no or only slight cell adhesion.

Bacterial Adhesion↗
PubMed1998

Detection of psychotrophic aeromonads in drinking water.

In the context of evaluating their pathogenic relevance, culture on solid media is the only approach presently suitable for culture of psychotrophic aeromonads from drinking water. In this respect, a check must be effected to ensure that the culture medium cannot engender selective culture losses for individual species. For this reason, media to which e.g. ampicillin has been added are unsuitable.

Aeromonas↗
PubMed1998

The maximum growth temperature and human pathogenicity of psychrotrophic aeromonads.

Determination of the maximum growth temperature of Aeromonas strains isolated from clinical material and endowed with pronounced propensity for adhesion to intestinal cells has demonstrated that all strains still grow at 39 degrees C, with this holding true for the majority of strains also at 40 degrees C. Since Aeromonas isolated obtained from water evidence to a large extent a markedly lower maximum growth temperature, the 39 degrees C growth criterion is a characteristic of Aeromonas strains isolated from clinical material.

Aeromonas↗
PubMed1991

The taxonomy and nomenclature of the psychrotrophic aeromonads.

Following the introduction of the DNA hybridization technique several genotypes have been separated from the older phenotypically described Aeromonas species. Work has been undertaken on some arbutin-negative psychrotrophic Aeromonas strains. These were differentiated into three genotypically and phenotypically identifiable groups. One group (I) is genetically related to A. sobria (type 208). The two other groups (II and J) can be separated genotypically and phenotypically from the A. sobria, A. veronii and A. hydrophila genotypes. Studies on ADH-negative anaerogenic surface water aeromonads showed them to be genotypically more distant from A. punctata type 239 than from type 545.

Aeromonas↗
PubMed1990

Temperature as an environmental factor influencing the pathogenicity of Aeromonas hydrophila.

Contamination of wounds by surface water and the aspiration of such water following an accident can lead to severe septic infection by A. hydrophila. As such water is often found at low temperatures, the question should be asked whether this particular water environment influences the pathogenicity of this organism. Some experiments have been undertaken to assess if the pathogenicity of A. hydrophila is affected by temperature. The pathogenicity of A. hydrophila adapted to the low temperature of ground and surface waters (10 degrees C) was tested in a mouse-model. The conclusions drawn from the experimental data indicate that the 50 per cent lethal dose of A. hydrophila suspensions are lower for those grown at low temperatures (10 degrees C) when compared to those grown at higher temperatures (30 degrees C). The generation and log phase periods support the above conclusion, in so far that low-temperature-adapted organisms, when exposed to high temperatures, grow faster than those organisms already adapted to higher temperatures.

Aeromonas↗
PubMed1989

A single-tube confirmatory test for E. coli using brilliant green mannitol methylumbelliferyl-beta-d-glucuronide tryptophane tryptone broth (BMMTT-medium).

The paper briefly describes the development of a third marker in the single tube technique used in the confirmation of E. coli in water. It has been shown that the third marker, is totally compatible with the markers of gas production from mannitol and indole from tryptophane. The principle of the third marker is to utilise the E. coli specific enzyme, beta-d-glucuronidase, which produces the photoluminescent methylumbelliferone.

Culture Media↗
PubMed1988

Aeromonas eucrenophila species nova Aeromonas caviae a later and illegitimate synonym of Aeromonas punctata.

Aeromonas caviae is a later and illegitimate synonym of Aeromonas punctata. In order to secure continuity in literature, it is proposed to use the trivial term "caviae type" in connection with the species name A. punctata temporarily especially for strains isolated in connection to diarrhoea in children. Aeromonas eucrenophila sp. nov. is described, type strain in NCMB 74. The new aerogenic psychrotrophic Aeromonas species is separated genotypically from Aeromonas hydrophila and Aeromonas punctata (caviae type).

Aeromonas↗
PubMed1981

[On the ecology of Plesiomonas shigelloides (author's transl)].

Studies on the generation time of P. shigelloides and its relation to incubation temperature have shown that this species in marked contrast to A. hydrophila does not multiply in temperature below 8 degrees C. These findings would explain the seasonal variations in the number of isolates from river-water observed in Japan. Colony counts of P. shigelloides organisms on IBG-agar from water of the river Main sampled during the month of August (water temperature 20 degrees C) have shown numbers of 10--100 c.f.u./ml. Thus P. shigelloides is present in surface water in Middle Europe. The presence of the germs could equally be demonstrated in the guts of many specimen of non-preying fish that had been caught during the months of July and August. When determining the bacterial species isolated from such material the possible presence of inositol-positive A. hydrophila strains has to be taken into account. Results of former studies on the suitability of Leifson-agar, Wilson-Blair- agar, SS-agar and IBG-agar then with pure cultures were confirmed by our work with faecal material from fish done this time. While favourable results were obtained on IBG- and SS-agar P. shigelloides could in no case be cultured on Leifson- and Wilson-Blair-agar.

Aeromonas↗
PubMed1980

[Studies on factors limiting self-purification of water. I. Experimental studies on the effects of degradable and of toxic substances on the ways of microbial self-purification of water (author's transl)].

The results of the present studies indicate that the inhibition of bacterial growth caused by discharge of toxic substances into water receiving wastewater of directly into wastewater cannot serve as a mechanism inhibiting degradation below the toxic threshold of the depression of oxygen consumption i.e. as determined by BOD. Therefore, this discharge-caused inhibition also does not explain the residues of degradable substances normally found. Observations were made on degradation in the laboratory using a model with creatinine as substrate and P. putida as microorganism. It was found that even "physiologic" and therefore, easily degradable substances as well as subtoxic concentrations of toxic substances (measured against a determined minimal concentration causing inhibition) if discharged into water receiving wastewater or into wastewater will interfere with the degradation of specific wastes (creatinine). The delayed and/or incomplete degradations in our model led to a formation of persisting residual concentrations of the waste substances introduced into the system. It is rather unlikely that such residuals will actually emerge in running water under natural conditions, because here the specific (creatinine) degrading organisms will invariably revert from the stationary phase to a renewed active phase (of exponential growth) whenever the system receives other discharges or even is diluted by other discharges. In their active phase the mixed populations of bacteria formed in nature will almost certainly completely metabolize whatever may left of degradable wastes (creatinine). The mere fact that the time needed for degradation can be lengthened so considerably by interfering "physiological" yet degradable substances as well as by subtoxic concentrations of toxins, offers an explanation for the degradability measured immanentally in defined time-intervals within the BODx taken as a measure of degradable "residual wastes" i.e. substances which are biologically degradable but are not degraded.

Bacteria↗
PubMed1977

[The methyleneblue reduction disc test (M.R.D.-test): a simplified method for the identification of Pseudomonas species (author's transl)].

The identification of Pseudomonas species in practice can be improved by testing the utilization of different organic compounds as single sources of carbon. The introduction of this kind of technique into routine laboratory work requires a simplification of the test system. In order to meet these requirements the methyleneblue reduction disc test (M.R.D.-test) had been developed. In this test discs loaded with different organic compounds are introduced into suspensions of the strain examined as single source of carbon. Before to these bacterial suspensions a mineral salts solution containing methyleneblue as a redox indicator had been added. With the help of this method the utilization of a large number of different organic compounds as single sources of carbon can be tested in a way which is neither laborious nor time consuming. The disc once prepared can be stored for some time, single strains can be tested without any difficulty as they are isolated during routine laboratory work.

Culture Media↗
PubMed1975

[The relation of aerogenic to anaerogenic aeromonads of the "Hydrophila-Punctata-group" in river water depending on the load of waste (author's transl)].

The analysis of the relation of the aerogenic and anaerogenic Aeromonas-Species of the "Hydrophila-Punctata-Group" in moving waters of a varying load of waste demonstrates that in the sewage water the anaerogenic subspecies A.hydrophila subsp. anaerogenes and A.punctata subsp. caviae predominate over the aerogenic species A.hydrophila and A.punctata with an average of 78%. Polysaprobic rivers and brooks show a similar relation. To the contrary, the aerogenic Aeromonads-mainly A.hydrophila-dominate over the anaerogenic Aeromonads in oligosaprobic brooks with a low range of variation of the individual value with 90% on the average. The alpha- and beta-mesosaprobic rivers show-with a great variation of the values indicated at each test place-a relation of aerogenic to anaerogenic Aeromonads of 39:61 for the alpha-mesosaprobics and 43:57 for the beta-mesosaprobics on an average; consequently, they are close to each other in average analysis. The great differences in the individual value of both groups seem, however, to make it possible that the determination of the relation of the aerogenic Aeromonads to the anerogenic could show a more sensitive system of waste contamination or of waste load than the saprobic system used in comparison. Since the anaerogenic subspecies A.hydrophila subsp. anerogenes and A.punctata subsp. caviae are very similar to each other from the ecological point of view and A.hydrophila of the aerogenic species is the widely predominating microorganism it seems to be sufficient for practical purpose to determine the relation of aerogenic to anaerogenic Aeromonads of the "Hydrophila-Punctata-Group"; a further differentiation does not assist in obtaining more information at the present time.

Aerobiosis↗
PubMed1975

[The detection of spores of the bacillus species within the scope of the hygienic control of water pollution (author's transl)].

Due to their differentiated nutritional requirements the species of the genus Bacillus found in large number in the waste matter and the upper layers of the soil and consequently in the surface water cannot multiply in biotopes of low nutritive content. However, they are spread to these areas as spores and are of extraordinary tenacity if not eliminated. Consequently, in the ground water and within the range of its utilization they represent an indicator of the degree of purification or contamination of the water with waste products or surface impurities; their number does not depend on the phase of self-purification (as e.g. the number of colonies) in the sense of the degradation of remaining substances still utilizable by pseudomonads. The concentration of spores of the Bacillus species in the surface water ranges from 1000-10000 per 50 ml of water. In undisturbed ground water 0-5 per 50 ml are found; in filtered ground water from near the banks and in such water that has been exposed to surface contamination 1000 per 50 ml have been found or even more; in the direction of infiltration - proportionate to the purification effect in the ground - decreasing numbers of spores of the Bacillus species are detectable. In "areas of subsequent germination" of the water supply and water utilization no multiplication of spores of the Bacillus species has been observed - provided no additional contamination occurs.

Aerobiosis↗
PubMed1975

[On bacterial aftergrowth in drinking and industrial water. II. Apparative and processing influence upon the growth and the possibility of disinfection of ion exchange resin filter systems (author's transl)].

The comparative examination of numerous ion exchange resin filter systems for discontinuous water softening on the market revealed that apparative and processing characteristics are of great influence upon the aftergrowth of bacteria in the water of ion exchange resin systems. Within the examination it was taken into consideration that on the end-delivery-tube of the water pipe with regard to the colony count the conditions were more unfavourable during the long standstill over a weekend (table 1) than during the week (table2). The less favourable conditions have therefore been examined separately. The work has been divided in six test series. In the first one 5 ion exchange resin systems the types A-E are simultaneously tested with regard to the colony count in the water at the inflow to the apparatus and after the passage of it; regeneration twice a week with sodium chloride. The data ascertained in the course of several weeks (without first data on mondays) and the separated mondays data are examined according to logarithmic transformation with the assistance of variance analysis and the Newman Keuls-test for differences. The results show (tab. 4 and 5) that apparative parameters and such relevant to the technical process (tab. 3) have an influence upon the bacterial after growth of the water. The most favourable ion exchange resin filter is type E because it shows more favourable values than all other systems and the tapwater. In the second test serie the systems A-E have been regenerated with 1% Chloramin T containing sodium chloride. The results show again the type E as the statistically significant most favourable system in comparison with the others and the tapwater. In the third test serie it has been examined whether the long period of standstill of the brine in the resin bed which has probably been responsible for the good results of the type E would lead to values just as favourable if transferred to another type of apparatus. ...

Bacteria↗
PubMed1975

[The methylene-blue-reduction-test (MR-test) and the micro-TTC-test for the determination of substances as sole source of carbon in the taxonomy of Pseudomonas species (author's transl)].

Two methods are described for the determination of substances as sole source of carbon for taxonomic tools: the Methylene-Blue-Reduction-Test and the Micro-TTC-Test. Both methods are giving results superior to the technique introduced by STANIER and co-workers and used hitherto in the taxonomic classification of Pseudomonas species. The evaluation of the comparative test results is based on the criterion that a substance is useful for taxonomic purpose provided that at least 90 per cent of the strains of a species are giving homogeneous results. - The MR-Test is superior to the Micro-TTC-Test concerning the reproducibility of the results. The Micro-TTC-Test is useful as a screening technique in the routine work and the primary investigation of numerous strains.

Acetamides↗
PubMed1975

[Investigations on the standardization of polytropic substances used in microbiological test procedures. I. Suitability of vitamin-free casein hydrolysates as standardizable source of N and C for bacterial growth (author's transl)].

Comparative testing of vitamin-free casein hydrolysates produced by Merck, Difco and Sheffield showed that the products are evidently fairly well standardised by the manufacturing specifications and satisfy requirements as polytropic source of N and C for microbiological test procedures in which high degree of reproducibility is demanded. Tests were conducted with strains of E. coli, A. punctata, P. aeruginosa and Myxobacter sp. and showed that differences within the trial groups in the colony count on the nutrient medium prepared with the three vitamin-free casein hydrolysates are accidental.

Aeromonas↗