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Biomedical subjects

H Rüden

Publications and source records attributed to H Rüden.

At least 127 records · Page 7Linked to original sources
PubMed1996

[Nosocomial infections in Germany--assessment and prevention. NIDEP Study, 1: On prevalence in surgery].

One aim of the NIDEP study (nosocomial infections in Germany: surveillance and prevention) was to determine in part 1 (surveillance) the prevalence of nosocomial infections (NI) in patients in surgical departments of 72 representatively selected hospitals in Germany. The surveillance was carried out by four previously validated physicians who applied the CDC criteria for NI. The overall rate of NI was 3.8%. Urinary tract infections (1.45%) and surgical wound infections (1.34%) were the most common NI. The highest rate of wound infections was noted after amputations (7.2%), conventional appendectomies (4.1%) or operations on the colon or rectum (3.8%). The use of perioperative antibiotics varied widely depending on the kind of operation and was not in accordance with international guidelines in all hospitals.

Adolescent↗
PubMed1996

[Postoperative wound infections in surgery--prevalence in Germany (Nosocomial Infections in Germany--Assessment and Prevention Study)].

Part of the NIDEP study was to determine the prevalence of surgical site infections in the surgical departments of 72 representatively selected hospitals. Four physicians, trained and validated in detecting nosocomial infections, carried out the surveillance, based on the CDC criteria for nosocomial infections. The prevalence of surgical site infections was 1.34% for all surgical patients (n = 5377) and 2.13% for all operated patients (n = 3383). Lower rates were found in patients with a low ASA score, clean wounds, and an average duration of the operation. Most surgical site infections were noted after amputations (7.2%), operations on colon or rectum (4.1%), and appendectomies (3.8%).

Cross Infection↗
PubMed1995

[Field study to obtain Legionella-free water from showers and sinks of a transplantation unit by a system of water filters].

The efficiency of filters for elimination of Legionella was examined in a ten month field study. Showers and sinks of twelve patient rooms were equipped with nylon 66-polyamid filters. Before filtration the total number of colonies was very high with an arithmetical mean of 1131 cfu/ml. This could be reduced by filtration at the sinks (mean = 205 cfu/ml). After equipping showers with filters we found a significant increase in the total number of colonies (mean = 1961 cfu/ml). In non-filtered water we found Legionella in nearly 90% of the 648 samples, the concentration extended to 300 cfu/ml (mean = 51 cfu/ml). After filtration the concentration of Legionella was up to 280 cfu/ml in 7.3% of the 665 samples. We calculated a logistic regression model to examine the effects of the age of the filters and the duration of their use since the last sterilization. These parameters were calculated from the time of the break through or retrograde contamination with Legionella. There were clear differences between shower and sink filters. Assuming a 5% probability of break through or retrograde contamination with Legionella, the sink filters should be sterilized every 3 weeks without regards to the age of the filters. In contrast the shower filters may be used for 3 weeks if they are sterilized weekly. If weekly sterilization is not feasible they should be used for 2 weeks only. In our study it was not possible to achieve Legionella-free water by changing either the frequency of sterilization or the age of the filters.

Baths↗
PubMed1995

[Air microbial burden at garbage sorting facilities].

At two german garbage sorting facilities, germ concentrations in the air were analyzed at different working environments (waste reception, manual sorting). At plant A, maximum concentrations of total bacteria (14700 CFU/m3), gram-negative bacteria (7279 CFU/m3) and moulds (> 84806 CFU/m3) occurred in the air at the final manual sorting belts. Referring to concentrations of total bacteria and moulds, concentrations in the air at the final sorting belts were significantly higher (p < 0.001) than at the other working environments. At plant B, the counts of total bacteria reached 7173 CFU/m3 in the air at the waste reception site and 5512 CFU/m3 at the manual sorting belt. Maximum concentrations for gram-negative bacteria were 247 resp. 206 CFU/m3 and 70919 resp. 60848 CFU/m3 for moulds. At the waste reception site, the aerial concentrations of total bacteria lay highly significantly (p < 0.001) and of moulds significantly (p < 0.05) above aerial concentrations at the manual sorting belt. As causes, an intensive mechanical pretreatment of recycle material at plant A and whirling up of sedimentary dust of the floor during manual sweeping of the material on to the transportation at plant B are discussed.

Air Microbiology↗
PubMed1994

Photochemical decomposition of organic compounds in water after UV-irradiation: investigation of positive mutagenic effects.

It should be investigated whether UV-disinfection of natural and contaminated organic substances in surface and drinking water may generate a positive mutagenic effect. Selected organic pesticides (atrazine, simazine, metobromurone, methabenzthiazurone, dichlorprop) and organic compounds naturally present in water (phenylalanine, tyrosine, polysaccharides) were examined in Ames-test (bacterial strains TA 98 and TA 100) and sister chromatid exchange (SCE)-test (V79 cells) before and after UV-irradiation. UV-irradiation with low- and high-pressure mercury vapor lamps was carried out in parallel experiments. Based on results in Ames- and SCE-test a mutagenic activity was not obtained for all samples, neither before nor after UV-irradiation.

Animals↗
PubMed1994

[Composting facilities. 2. Aerogenic microorganism content at different working areas of composting facilities].

At two composting facilities (plants D and E), contamination of the air with total bacteria and mould fungi, and in addition with gram-negative bacteria (only at plant D) was analyzed at different indoor sites and outdoor in the vicinity. Statistical validity of the determination of contents of microorganisms in air samples was guaranteed by the collection and analysis of 30 parallel samples. At plant D, total bacteria concentrations in outdoor air ranged from 106 to 15,618 CFU/m3 air (median: 495 CFU/m3 air), gram-negative bacteria concentrations ranged up to 71 CFU/m3 air (median: below the detection limit of 35 CFU/m3 air), and mould fungi reached 7,138 CFU/m3 air (median: 141 CFU/m3 air). Highest concentrations of total bacteria above the upper detection limit (> 84,806 CFU/m3 air, sample volume: 28.3 l) and of mould fungi (38,940 CFU/m3 air) occurred at the place where three months old compost was mixed, highest concentrations of gram-negative bacteria (14,134 CFU/m3 air) were measured during mixing of fresh compost (younger than 8 days). Maximum and median values of the examined microorganisms ranged so high that special protective means for personnel working directly beneath the mixing process seem to be necessary under hygienic aspects. Raw and clean air at the composting filter at plant D showed highly significant differences concerning air concentration of gram-negative bacteria and mould fungi, indicating a good separation efficiency for these types of microorganisms. Maximum and median values of gram-negative bacteria and mould fungi concentrations (all < 1,000 CFU/m3 air) measured in clean air behind the composting filter lie in the range of normal outdoor air. Merely total bacteria show statistical significant differences to outdoor air with median values of clean air of 1,979 CFU/m3 air (edge of filter) resp. 3,110 CFU/m3 air (upside the filter) and with maximum values of above 30,000 CFU/m3 air in each case. In the outdoor air at plant E, total bacteria concentrations ranged from 362 to 7,633 CFU/m3 air (median: 1,312 CFU/m3 air), mould fungi ranged from 115 to 4,072 CFU/m3 air (median: 345 CFU/m3 air). Highest concentrations of total bacteria and mould fungi (all analyses above the upper detection limit of 21,201 CFU/m3 air; sample volume: 113,2 l) occurred during shredding of a mixture of kitchen and green wastes and of shrubs. During experimental shredding of separately collected panty diapers air concentrations of total bacteria ranged from about 19,000 CFU/m3 air to > 21,201 CFU/m3 air.(ABSTRACT TRUNCATED AT 400 WORDS)

Air Microbiology↗
PubMed1994

[Composting facilities. 1. Microbiological quality of compost with special regard to disposable diapers].

At three different composting facilities, co-composting of used panty diapers with an addition of 10% (weight) to the usual plant input was investigated for various hygienic and microbiological parameters. In nearly any case, a sufficient degree of germ reduction above 99.9% could be observed by determination of reduction rates of B. subtilis spores. The concentrations of "total microorganisms" ranged from 3.9 x 10(5) to 3.3 x 10(11) colony forming units per gram compost (CFU/g) in composts without and from 3.3 x 10(5) to 4.7 x 10(9) CFU/g in composts with panty diapers in the input. The concentrations of "gram-negative bacteria" ranged from 3.3 x 10(4) to 1.3 x 10(9) CFU/g (without panty diapers) resp. from 3.3 x 10(5) to 3.5 x 10(8) CFU/g (with panty diapers), the concentrations of "fecal streptococci" from 1.7 x 10(3) to 7.7 x 10(7) CFU/g (without panty diapers) resp. from 1.4 x 10(4) to 1.4 x 10(8) CFU/g (with panty diapers). Facultatively pathogenic microorganisms showed a broad variety, but no common trend in composts with and without panty diapers in the input. Statistical validity of the determination of contents of microorganisms in compost samples was guaranteed by the collection and analysis of 20 parallel samples with an average sample mass of 10 to 15 kg. From the analyzed quantitative and qualitative hygienic-microbiological parameters, it can be concluded that no negative hygienic-microbiological effects, caused by the addition of 10% (weight) of used panty diapers in the input, have to be expected. Under the aspects of epidemiologic hygiene, composting of used panty diapers together with usual input materials seems to cause no increased risks under the tested conditions. Under the aspect of consumer protection, there is no increase in the risk of infection when using compost produced with addition of panty diapers, compared to compost produced without panty diaper addition to the input.

Bacillus subtilis↗
PubMed1994

[Bacteria-reducing properties of copper-containing and non-copper-containing materials. II. Relationship between microbiocide effect of copper-containing materials and copper ion concentration after contamination with moist and dry hands].

The bactericide quality of different materials containing copper (copper, brass, brass-sheet) was tested and particularly the effect of humidity and copper-concentration was examined. In first examinations (I. communication) (19) the materials were contaminated by hands, which were dipped into a suspension of different microorganisms (Micrococcus luteus, Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Enterobacter cloacae, Pseudomonas aeruginosa). The survival rate of the microorganisms on the surfaces was determined after defined exposure times (0, 5, 30, 60, 120 min). The following ways of contaminating the test materials were chosen: single contamination with wet hands, repeated contamination with wet and dry hands. In this examination the results were tested for statistical significance and in parallel experiments the copper-concentration on the surfaces of the materials was determined. Materials containing copper contaminated with wet hands show a significant bactericide effect after an exposure time of 120 min. The bactericide effect on Micrococcus luteus and Pseudomonas aeruginosa is inhibited after contamination with dry hands. This results can not be explained by a different copper-concentration on the surfaces of the materials, because a statistically significant difference of copper-ion concentrations between contamination with wet and dry hands could not be obtained.

Bacteria↗
PubMed1993

[Bacterial reducing qualities of copper-containing and non-copper-containing materials. I. Contamination and sedimentation in humid and dry conditions].

In this examination the bactericide qualities of different materials were tested. Particularly the effect of humidity was examined. 3 materials containing copper ("copper", "brass" and "brass sheet") and 2 materials not containing copper ("polyamide B" and "high-grade steel") were tested. The surfaces of the 5 types of material were contaminated with a suspension of 2 different bacteria species (Staphylococcus aureus and Micrococcus luteus). After defined exposure times the survival rate of the microorganisms on the surfaces was determined by the standardized method of the "Guidelines of the German Society of Hygiene and Microbiology". Additionally the sedimentation of airborne microorganisms on the materials was tested by determining the number of colony-forming-units after defined exposure times. In further examinations the materials were contaminated by hands, which were dipped into a suspension of different microorganisms (Micrococcus luteus, Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Enterobacter cloacae and Pseudomonas aeruginosa). The following ways of contaminating the test materials were chosen: single contamination with wet hands, repeated contamination with wet and dry hands. After defined exposure times the survival rate of the microorganisms on the surfaces was determined. The results show, a bactericide quality of copper depends on the percent of copper-content of the tested materials, exposure time, humidity, frequency of contamination and bacteria species. Humidity and only single contamination cause a reduction of bacteria. Reduction of gram-negative bacteria is more easily than reduction of gram-positive bacteria. Enterococcus faecium shows the highest, Pseudomonas aeruginosa the lowest reduction rate of bacteria in the following sequence: Enterococcus faecium, Escherichia coli, Enterobacter cloacae, Micrococcus luteus, Staphylococcus aureus and Pseudomonas aeruginosa.

Air Microbiology↗
PubMed1993

[The effect of the ventilation rate on air particle and air microbe concentration in operating rooms with conventional ventilation. 1. Measurement without surgical activity].

The question was if a reduction of airborne particles and bacteria in conventionally (turbulently), ventilated operating theatres in comparison to Laminar-Airflow (LAF) operating theatres does occur at high air-exchange-rates. Within the framework of energy consumption measures the influence of air-exchange-rates on airborne particle and bacteria concentrations was determined in two identical operating theatres with conventional ventilation (wall diffusor panel) at the air-exchange-rates 7.5, 10, 15 and 20/h without surgical activity. This was established by means of the statistical procedure of analysis of variance. Especially for the comparison of the air-exchange-rates 7.5 and 15/h statistical differences were found for airborne particle concentrations in supply and ambient air. Concerning airborne bacteria concentrations no differences were found among the various air-exchange-rates. Explanation of variance is quite high for non-viable particles (supply air: 37%, ambient air: 81%) but negligible for viable particles (bacteria) with values below 15%.

Air Microbiology↗
PubMed1993

[The effect of the ventilation rate on the air particle and air microbe concentration in operating rooms with conventional ventilation. 2. Measurement during surgical activity with respect to surgical personnel number and surgical activity phases].

For measurements with surgical activity, it was investigated if the air-exchange-rate has a significant influence on airborne particle and bacteria concentrations in two conventionally ventilated operating theatres. Next to that the influence of number of personnel in the operating theatre and the various operating phases were calculated (explanation of variance). Statistical differences were found for airborne particle concentrations and a few for airborne bacteria concentrations in supply and ambient air. From the hygienic point of view these differences must be considered to be irrelevant because of the little margin (less than one lg-step) between the values. The comparison of all air-exchange-rates as well as that between the two air-exchange-rates in the two operating theatres show that the number of personnel present in the operating theatre has the most influence on airborne particle concentrations variance. Concerning airborne bacteria concentrations explanation of variance by the treatment factors air-exchange-rate, personnel and operating phase is negligible. Summarizing the low (7.5 and 10/h) and high (15 and 20/h) air-exchange-rates did not increase the explanation of variance for airborne particle and bacteria concentrations although the differences were on a significant level.

Air Microbiology↗
PubMed1993

The efficacy of low temperature plasma (LTP) sterilization, a new sterilization technique.

The efficacy of low temperature plasma (LTP) sterilization, a newly developed sterilization procedure was tested. Following experiments were carried out: Determination of the most resistant test organism, influence of 10% and 20% defibrinated sheep blood or varying salt concentrations on the efficacy of the sterilization process, influence of the carrier position in the sterilization chamber and in the sterilization pouches, influence of a loaded sterilization chamber, comparative efficacy of EO and LTP, steel carriers with a blood burden of 0%, 5% and 10%, comparative efficacy of EO and LTP, strip carriers in endoscopes, blood burden 0% and 10%, with and without adaptors, evaluation of two bioindicator models. B. pumilus was the test spore that overall seemed to be most resistant to the sterilization procedure. Supplementation of the test suspension with blood or saline crystals resulted in significantly reduced efficacy and has to be avoided in practical operation. The fully loaded sterilization chamber or the position of germ carriers on the shelves had no negative influence on the effectivity of the sterilization process. There were no significant differences between EO and LTP, the blood burden not exceeding 5%. 10% blood burden resulted in a significantly weaker action of LTP. For sterilization of long lumens adaptors containing hydrogen peroxide are necessary. An appropriate bioindicator tube model is introduced.

Aspergillus niger↗
PubMed1992

[Effectiveness of instrument disinfectants under increased protein exposure and for standing times up to two weeks].

To examine the possibility of prolongation of the standing times of instrument disinfectants, in vitro tests under high albumin exposure and tests in clinical practice were done. Concerning in vitro tests: The bactericidal effectiveness of 7 commercial preparations for instrument disinfection with different basic substances was determined in quantitative suspension tests and of 8 preparations in practice-oriented tests according to the guidelines for testing and approval of instrument disinfectants by the DGHM (German Society for Hygiene and Microbiology). Tests were carried out under increased albumin exposure and at prolonged standing times up to 12 days. The instrument disinfectants showed microbicidal efficacy up to 12 days at working concentrations slightly increased in relation to the concentrations listed by the DGHM. Concerning tests in clinical practice: In 4 clinical wards (intensive care unit, cystoscopy unit, urological operation unit, gastroenterological endoscopy unit with ERPC) the preparations for instrument disinfection were tested up to 12 days in respect to the protein exposure and the disinfecting activity of the working solution. The working solution was not renewed during the 12 days. The inserted instruments were recorded. Concentration of the disinfectants and the protein concentration were daily determined. Disinfecting activity was examined by practice-oriented microbiological tests. The highest protein exposure was 0.098% after a standing time of 12 days. A loss in concentration of disinfectants could not be found. Nevertheless independent from the protein exposure there was a loss in disinfecting activity of the tap water diluted specimens from the clinical practice. Loss in activity could not be seen in the specimen from laboratory parallel tests, which were diluted by water of standard hardness. The loss in disinfecting activity of the tap water diluted preparation from the gastroenterological endoscopy unit versus a dilution by water of standard hardness could be confirmed in control experiments (practice-oriented tests with S. aureus over a period of 5 days).

Albumins↗
PubMed1991

Investigations into the efficacy of different procedures for surgical hand disinfection between consecutive operations.

In order to examine whether thorough surgical hand disinfection (handwashing plus hand disinfection) between consecutive operations is necessary, tests were carried out simulating normal clinical conditions. The tests were performed according to the guidelines for the evaluation of disinfection procedures of the German Society for Hygiene and Microbiology. Surgical hand disinfection was as follows: handwashing with soap without antimicrobial additives and subsequent 5-min disinfection with 60% n-propanol. This was followed by simulated operations of 30 or 120 min duration with a 30-min break between operations, during which half of the test group kept on the surgical gloves, while the other half removed them. The second surgical hand disinfection was done without prior handwashing by 50% of the test group. The disinfection time was reduced from 5 to 1 min by 50% of the test group. The results were evaluated by means of explorative data analysis and inductive statistical methods. Removing the surgical gloves during the interoperative break did not result in significantly higher numbers of colony forming units (cfu) compared with retaining the gloves. This was also the case after a subsequent handwashing. At the second surgical hand disinfection, after a simulated operation of 60 min duration (including break), there was no significant difference in the numbers of cfus between the test group who had washed their hands and those who had not. Reducing the disinfection time from 5 min to 1 min was not associated with a significant increase in the number of cfus. However, after a simulated operating time of 150 min (including the break), the second surgical hand disinfection with handwashing resulted in a significantly lower number of microorganisms than disinfection alone. In half the tests, the numbers of cfu were significantly lower when the test group disinfected their hands for 5 min rather than 1 min.

1-Propanol↗
PubMed1991

Physiological characterization and identification of Listeria species.

A total of 136 strains of the genus Listeria were physiologically characterized using 329 miniaturized tests. Overall similarities of all strains were determined by numerical taxonomic techniques using the UPGMA algorithm and the SSM and SJ coefficients. A total of 10 clusters (2 or more strains) and 1 single-member cluster were defined at the 95.1 to 95.8% similarity levels (SSM). The same clusters were found at the 76.8% to 77.8% similarity levels (SJ). Strains of L. seeligeri, L. welshimeri, L. ivanovii, L. murrayi and L. grayi were found in separate clusters and formed homogeneous taxospecies. In contrast, strains of L. monocytogenes and L. innocua formed five heterogeneous clusters and one single-member cluster. For differentiation of the phena the following tests are useful: utilization of D-xylose, D-xylitol, D-ribose, D-galactose, alpha-methyl-D-mannoside, methyl-alpha-D-glucopyranoside, inulin and L-rhamnose, acid production from D-glucuronate, alpha-D-galacturonate, alpha-methyl-D-mannoside, methyl-alpha-D-glucopyranoside, D-xylose, L-lyxose, D-sucrose, alpha-D-melizitose, D-tagatose, and D-ribose and hydrolysis of pNP-alpha-D-glucopyranoside, pNP-alpha-D-mannopyranoside and 2-deoxythymidine-5'-pNP-phosphate. Independent of the assignment of some strains of L. monocytogenes and L. innocua to the same cluster, members of these species can be separated by hydrolysis of D-alanine-p-nitroanilide.

Cluster Analysis↗