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Biomedical subjects

H E Müller

Publications and source records attributed to H E Müller.

At least 73 records · Page 4Linked to original sources
PubMed1988

Experimental studies of detection and processing of Legionella spp. in public drinking water supplies.

Studies were conducted to improve the detection and processing of Legionella spp. in public drinking water supplies. The survival of legionellas was the best in tap water samples, stored at 4 degrees C. Comparing investigations showed that the most cells could be recovered from glassware whereas plastics adsorbed legionellas up to 80-90 percent on their surfaces. A method of enrichment and isolation of legionellas from large volumes of tap water samples was developed using precipitation by Fe(OH)3. Finally, a comparison of BCYE alpha-agar containing different mixtures of antibiotics revealed that the supplement of vancomycin, polymyxin, and glycine (VPG) gave better results than of cephalothin, colistin, vancomycin, and cycloheximide (CCVC), especially, because of the different growth of various serogroups of Legionella pneumophila on the CCVC medium.

Culture Media↗
PubMed1988

Occurrence and parameters of frequency of Legionella in warm water systems of hospitals and hotels in Lower Saxony.

A total of 1241 water samples was investigated from 103 hospitals and 62 hotels in Lower Saxony 1985-87. 331 of 949 samples from hospitals and 26 of 292 samples from hotels were Legionella positive. All together 70% of the hospitals and 18% of the hotels investigated were Legionella positive, and 836 strains of Legionella were isolated (Table 1). As they could be diagnosed they belong to L. pneumophila SG1 306 strains, SG2 36 strains, SG3 127 strains, SG4 45 strain, SG5 29 strain, SG6 106 strains, SG9 13 strains and SG10 13 strains. Further 134 strains belonging to L. pneumophila but not to SG1-SG12 show cross reactions with serogroups 5, 8, and 10. Finally, 16 strains belong to L. dumoffii and 1 strain to L. anisa (Table 2). The following parameters of water samples were studied, too: temperature, pH value, conductivity, concentration of iron, of organic matter, of other bacteria, occurrence of amoebas, and the materials of water plumbing systems. Most samples contained concentrations of Legionella in the range of 10(1)-10(3) CFU/ml, highest concentrations were 10(5) CFU/ml (Fig. 1). Most frequently, Legionella were isolated within the range of temperature of 35-45 degrees C. However, a few of the water samples were positive for Legionella even up to 66 degrees C (Fig. 3). The conductivity has no and the pH value (Fig. 2) has only little influence on the occurrence of Legionella. There is a positive correlation between concentration of iron and frequency of Legionella (Fig. 4). Also organic matter (Fig. 6) and amoebas (Table 3) seem to enhance the occurrence of Legionella. Plumbing systems consisting of copper showed an inhibitory effect on Legionella during the first five years, whereas no effect could be detected in older systems (Fig. 5).

Amoeba↗
PubMed1987

[Comparative studies of the kinetics of hygienically relevant microorganisms in activated sludge].

Several samples were taken regularly from 14 different activated sludge ponds in 11 municipal wastewater treatment plants (Table 1). During 7 days, the samples were supplied with oxygen continuously by stirring and the following parameters were determined daily in the filtrate and also in the insoluble sludge: total bacterial plate count grown at 36 degrees C; additionally the oxidase-positive bacteria; the gram-negative bacteria grown on MacConkey agar; also the lactose-positive bacteria of these; C. coli; aerobic endospore-forming bacteria; and protozoa. Furthermore, salmonellae were determined in some aerated and non-aerated samples. The sludge index (SI) as the quotient of volume and dry weight of sludge, in addition the optical density of the sludge-free filtrate was measured. The total bacterial plate count, the count of gram-negative rods, and the lactose-positive enterobacteria were found to be reduced in 12 of the 14 investigated series. The amount of E. coli diminished in as many as 13 of the 14 series and the oxidase-positive bacteria dropped in 11 of 13 cases. The concentration of aerobic spore-forming bacteria remained constant or increased. A propagation of salmonellae was observed only under anaerobic conditions in sludge (Fig. 4). An analysis of the bacterial dynamics shows that the propagation of all bacteria occurs mainly in the free water. Also the reduction of bacteria is more in the free water than in the insoluble flocs of sludge (Table 2). Hence it follows that the flocs are not the centres of microbial activity although most bacteria (medium 76%) are attached to them. Moreover, we found characteristic relations between SI and optical density of the filtrate for the different wastewater treatment plants. There is also a positive correlation between the frequency of protozoa in sludge and the SI (Fig. 2). The SI is correlated positively also with the reduction rate of the most groups of bacteria, excluding the aerobic spore-forming bacteria (Fig. 3). This fact shows a conflict of two possibilities. On the one hand, the reduction of bacteria in wastewater is being improved by increasing SI but the deposition of such sludge is poor. On the other hand, sludge with a lower SI is settling better but the removal of bacteria by protozoa is diminished. Altogether, the sedimentation of flocs is the most important step of elimination of fecal bacteria from wastewater. The process reduces the concentration by the factor 10. Therefore, the successive sedimentation of raw sewage and activated sludge is about 10 time more effective than the simultaneous sedimentation.

Animals↗
PubMed1987

[Quantitative studies of the elimination of Salmonellae by biological wastewater treatment].

The wastewater pretreatment plant of Braunschweig works as a conventional, one step activated sludge plant without primary settling tanks. There were about 37,000 m3 per day of effluent during our investigations. During some months daily quantitative determinations of salmonellae were performed in the raw wastewater, in the activated sludge, and in the effluent. The mean concentrations of salmonellae were in the raw wastewater 2 X 10(5)/l and in the effluent after 11h of aeration and then settling 2 X 10(4) cells/l. The concentrations of salmonellae varied about the factor 10(3) (limits 10(2) to 10(5)). A small peak in the spring, a big peak in the late summer, and a week pattern were observed. The most salmonellae were adsorbed to unsoluble flocs of sludge, about 30-35% of the salmonellae only were found freely in the water and from that about 60% were concentrated round the flocs. Therefore, one step of settling removes about 90% of all salmonellae. In generally terms, the settling seems to be the most important step of removal of salmonellae from wastewater. Furthermore, the rate of removal is depending of the concentration. High concentrations of salmonellae cause a strong reduction and conversely. An immediate removal of salmonellae was observed in about 60%, however, there was a propagation of salmonellae in 30% of all samples, especially under conditions of low aeration, in an anaerobic environment, respectively.

Abattoirs↗
PubMed1986

Quantitative differences in the infectiousness and pathogenicity of 187 Salmonella serotypes or species.

The present paper makes use of the epidemiological statistical data from 372,496 salmonellae isolated in man and 63,345 isolations from non-human material, e.g. animal foodstuffs, domestic animals and food of animal origin, surface waters and drainage waters. There were a total of 187 different serotypes. The data are derived from publications of the Federal Health Office, Berlin, for the period 1972-76; the Center for Disease Control, Atlanta, Georgia for the years 1968-74; and from various publications and our own studies between 1954-76. On the basis of theoretical deduction and by inductive procedures, Salmonella quotients were derived as quantitative statistical values for the infectiousness or pathogenicity of the individual serotypes in man or in animals. They result from the relative frequency of a serotype in man in relation to the relative frequency in non-human material, in animal food or surface water. The Salmonella quotients for the pathogenicity in animals can also be calculated in a similar way. The values vary about the factor 10(5) in the individual serotypes. It is inferred from this that infectiousness and pathogenicity vary by the same order of size. The Salmonella quotients are constant over many years and evidently also all over the world for most serotypes. Salmonella quotients with numerical values less than 1 indicate a depletion of the corresponding serotype in man. Numerical values greater than 1 indicate an accumulation. Conclusions can hence be drawn with regard to lower or higher infectiousness and pathogenicity.

Animals↗
PubMed1986

Occurrence and clinical significance of tyrosine clearing positive Citrobacter freundii in human faecal specimens.

59 tyrosine clearing positive Citrobacter strains were isolated from a total of 2062 human faecal specimens, specifically from 1167 healthy people and from 895 patients suffering from different gastrointestinal syndromes. All strains were identified biochemically as Citrobacter freundii. Citrobacter diversus 100% positive for tyrosine clearing could not be isolated in any case. Citrobacter freundii was found twice as frequently in stools of healthy human beings than of patients. There is a statistical significance of p less than 0.05 for the occurrence of tyrosine clearing Citrobacter freundii in healthy persons.

Citrobacter↗
PubMed1986

Proteus penneri showing a green colour reaction with Kovacs' indole reagent.

All 33 investigated strains of Proteus penneri gave a green colour reaction with Kovacs' indole reagent after an incubation of about three days at 36 degrees C. Furthermore, 26% of the 51 strains of Proteus mirabilis studied also showed the green colour reaction but somewhat more weakly. The initial compound of this reaction seems to be a product of tryptophan metabolism which is formed only under aerobic conditions.

Culture Media↗
PubMed1986

Isolation of Serratia fonticola from birds.

Eight hundred and sixty-seven strains of gram-negative rods obtained from fecal specimens of 90 wild European birds were isolated on selective media. Eighteen of these were identified as Serratia fonticola both biochemically and by DNA hybridization. The biochemical characteristics of the new strains are compared with published results.

Animals↗
PubMed1986

Production and degradation of indole by gram-negative bacteria.

The indole reaction is performed in various modifications with regard both to the reagents and to the media used. Especially the medium has hitherto attracted little attention and there are divergent recommendations for its composition. The comparison of some broths without and with addition of tryptophan after incubation with different indole-positive species revealed that tryptone without tryptophan yielded stronger reactions than with tryptophan added. Other broths showed stronger reactions with tryptophan. Investigations revealed that numerous indole-positive as well as indole-negative species possess an enzyme system degrading indole. It is induced after one or two days of incubation and acts slowly. All species of the Morganella-Proteus-Providencia group possess it, as does Serratia. Some other species show different characteristics. The production of indole from peptone containing tryptophan and the degradation of indole by such species of bacteria are due to figures showing one or more peaks depending on time. Any false indole reactions described up to now may also be explained by the antagonism of the two enzyme systems. Therefore, the indole reaction should be standardized with regard to the medium used to avoid some of these difficulties.

Culture Media↗
PubMed1986

Occurrence and pathogenic role of Morganella-Proteus-Providencia group bacteria in human feces.

A total of 2,693 fecal specimens, with 1,422 from healthy persons and 1,271 from patients suffering from enteric diseases, was investigated to isolate species of the Morganella-Proteus-Providencia group and to evaluate the role of these bacteria in intestinal disorders. Most strains were isolated from two media, i.e., blood agar and tryptophan agar. Two of the species were more frequently found in diarrheal cases than in healthy controls. These species were Morganella morganii and Proteus mirabilis. Two new species of Enterobacteriaceae, i.e., Proteus penneri and Providencia rustigianii, were found in 33 and 5 people, respectively. However, these two species were not found more frequently in the diarrheal cases.

Culture Media↗
PubMed1985

[Hygienic aspects of agricultural land applications of wastewater and sewage sludge].

Wastewater can be removed either by introducing it into rivers or by land application. Both methods are burdened with different hygienic risks. Generally, the danger of disease infections associated with agricultural land application of wastewater is overestimated. On the other hand, the potential health hazard caused by the introduction of wastewater into rivers or coastal waters are underevaluated. Reasons of hygiene are given, however, the main cause of the hygiene risk is due to cultural and social aspects.

Agricultural Workers' Diseases↗
PubMed1985

Detection of hydrogen peroxide produced by microorganisms on an ABTS peroxidase medium.

Previously published methods to detect the production of hydrogen peroxide by microorganisms have been of limited usefulness for routine diagnosis because the sensitivity of some of these procedures does not allow the isolation of single H2O2-producing colonies. The new medium containing 2,2'-azino-di (3-ethyl benzthiazoline-6-sulphonic acid) and horseradish peroxidase is more sensitive and faster than established methods.

Benzothiazoles↗