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H Rüden

Publications and source records attributed to H Rüden.

At least 109 records · Page 6Linked to original sources
PubMed1998

[Inactivation of chlorhexidine for in vitro testing of disinfectants].

An insufficient neutralization of chlorhexidine (4%), tested in vitro against Enterococcus faecium ATCC 6057, was suspected in the quantitative suspension test although the combination Tween 80, cysteine, histidine and saponine was assessed as sufficient for neutralising chlorhexidine. Bactericidal activity of each neutralising compound and their combinations was excluded. Sufficient neutralization was observed when all dilution steps and the corresponding agar plates were supplemented with the neutralising compounds. Successful neutralization in broth is not equivalent with successful neutralization in tryptic saline. We suggest to supplement at least the agar plates of the first dilution step with neutralising compounds when testing chlorhexidine.

Anti-Infective Agents, Local↗
PubMed1998

Investigations on the survival time of outdoor microorganisms on air filters.

Outdoor microorganism survival on air filters was examined in 16-day field investigations. Using a mobile filter testing device, samples of fiberglass pocket filters (filter class F7) were ventilated with outdoor air, and their microorganism contents were determined at 1, 2, 4, 8 and 16-day intervals. The results showed a mean survival time of microorganisms deposited on the air filters of 1 to 3 days.

Air Microbiology↗
PubMed1998

[Diagnostic training for the surveillance of nosocomial infections: what is possible and significant?].

The data of surveillance of nosocomial infections are used as clinical indicators of quality. Their diagnosis must therefore be accurate. One hundred medical records from surgical and intensive care patients were used to assess the accuracy of diagnosing nosocomial infections according to CDC definitions. All case histories included signs and symptoms of infection. There were 45 patients with a total of 60 nosocomial infections (18 urinary tract infections, 18 surgical site infections, 11 lower respiratory tract infections and 13 other infection types). After evaluating the medical records, 18 physicians independently decided whether or not there was a nosocomial infection and, if so, the type of underlying infection. Their results were compared to the diagnosis of two experienced physicians (gold standard). Twenty-five cases were assessed on each of four consecutive days and the results were discussed with the experienced physicians on the following morning. The discussions of the first day may thus have been influenced by the results of the following days. Overall sensitivity was 85.4% (Cl95 82.8-87.8%) and overall specificity was 97.1% (Cl95 95.8-98.0%). Among the most common types of nosocomial infections, urinary tract infections had the highest sensitivity (90.1%), followed by surgical site infections (87.3%) and lower respiratory tract infections (85.8%). The specificity for these types of infections was 98.2%, 98.9% and 99.5%, respectively. Although the method of investigation used does not fulfill the formal requirements of a validation study for diagnosing nosocomial infections, it seems useful for training in the diagnostics of nosocomial infections or for intermittent evaluation of criteria before starting surveillance activities. This method is useful for training the application of CDC definitions, particularly when the medical records are reduced to case studies that include only the basic information on determining the presence of a nosocomial infection in order to evaluate a large number of suspected cases in a short period of time.

Centers for Disease Control and Prevention, U.S.↗
PubMed1998

Direct detection of Pneumocysytis carinii in outdoor air: preliminary results of a field study.

P. carinii causes pneumonia in immunocompromised patients. New studies are suggestive of the de novo infections. Although P. carinii is believed to be ubiquitous it has not been detected directly from outdoor air. Therefore, outdoor air samples (n = 20) of 5 m3 were collected onto gelatin filters (pore size: 3 microns) on a cemetery using a suction pump (Sartorius MD8). Five samples were silver-stained, five samples were stained with an indirect immunfluorescence test kit, the remaining ten samples were stained with the combinations of the two individual stains. In a total of 100 m3 outdoor air one cyst resembling P. carinii was detected by the methenamine silver stain. Other cells not resembling P. carinii were found with a silver stained cell wall and positive fluorescence. The natural reservoir of P. carinii remains unknown. The indirect immunfluoresence which is common in the clinical laboratory is probably not specific enough for environmental samples.

Air Microbiology↗
PubMed1997

Comparison of screening methods to identify methicillin-resistant Staphylococcus aureus.

Screening methods to identify methicillin-resistant Staphylococcus aureus (MRSA) were compared using 96 isolates representing 17 distinct clones. The sensitivity of four commercial agglutination tests was determined in comparison to the tube coagulation test, and the results related to the presence of the coagulase gene. The broth screening test, agar dilution test and disc diffusion test were carried out, and the results related to the presence of the mecA gene. Mannitol salt agar and Iso-Sensitest agar with varying salt supplements were used. All agglutination tests had high rates of detection of Staphylococcus aureus (95.8-99.0%). Resistance in mecA gene-positive Staphylococcus aureus isolates was correctly detected by the oxacillin broth test, the agar dilution test and the disc diffusion test on mannitol salt agar, whereas on Iso-Sensitest agar detection rates were lower (between 68.5% and 94.4%, depending on the salt supplement). Incubation of the Iso-Sensitest plates for 48 hours significantly improved the rate of detection of resistance, but increased the major error rate up to 71.4%. MecA gene-positive Staphylococcus aureus isolates not detected by the disc diffusion test on Iso-Sensitest agar had significantly lower oxacillin minimal inhibitory concentration values and were significantly less resistant to a variety of antibiotics. Thus, mannitol salt agar might be a suitable medium for use in the disc diffusion and agar dilution test to detect resistance to oxacillin in Staphylococcus aureus.

Agglutination Tests↗
PubMed1997

[Breathing circuit exchange in intensive care. Once daily once weekly?].

UNLABELLED: In an investigation of infection control methods for respirator systems in 89 randomly selected German intensive care units as a part of the NIDEP study (Nosocomial Infections in Germany--Surveillance and Prevention), it was found that respirator systems were exchanged daily in about 50% of the intensive care units. However, Craven et al. found that changing circuits (including tubing and exhalation valve and the attached humidifier) every 24 h rather than every 48 h was independently associated with the occurrence of nosocomial pneumonia. On the basis of these results and recent studies, the current situation in the literature was analyzed in order to make recommendations for exchanging ventilator circuits. METHODS: Based on the extensive analysis of the literature by the Hospital Infection Control Practices Advisory Committee (HICPAC), we could limit our investigation to the years after 1994. A MEDLINE search was done, and abstracts from congresses of the past few years were considered. The main focus of the analysis was the development of pneumonia and not the contamination of the breathing circuit. The following methodological factors were analyzed for the most important published studies: design, applied definitions of pneumonia, sample size, comparability of study groups, inclusion and exclusion criteria. The results of the different studies were compared considering the potential bias factors. RESULTS AND DISCUSSION: There were nine prospective controlled studies on this topic. In all studies, the authors tried to investigate whether a longer interval between ventilator circuit exchange (more than 48 h) is safe or whether it is possible to leave the circuits unchanged (without using breathing filters). The design and results of the available studies were analyzed. The three most important studies were compared very carefully (Table 1 and 2), and a recommendation for infection control measures for ventilator circuits was made as a modification of the HICPAC guidelines. In addition, the device-associated pneumonia rates of ventilated intensive care patients in the NIDEP study were analyzed separately according to a daily or a 48-h or longer interval of ventilator circuit exchange. For patients with daily exchange, we found a device-associated rate of 17.4 per 1000 ventilator days and for those with longer intervals a rate of 7.9 per 1000 ventilator days. Only considering those patients without heat and moisture filters, the figures were 14.8 versus 6.1. These differences were not significant because of the small number of patients investigated. CONCLUSION: The available studies show clear advantages of not routinely exchanging the ventilator circuit, including tubing, exhalation valve and the attached humidifier, more often then every 7 days for an individual patient. Based on these findings, the current practice in most German intensive care units should be reevaluated.

Clinical Trials as Topic↗
PubMed1997

[Effectiveness of alcoholic hand disinfectants against methicillin resistant Staphylococcus aureus].

In order to determine the efficacy of hand disinfectants based on alcohol against three MRSA strains and 3 methicillin-susceptible S. aureus strains (MSSA), 1-propanol (60%) as well as Sterillium and Spitaderm were investigated in the quantitative suspension test at various dilutions and reactions times (15, 30 and 60s). All undiluted disinfectants revealed reduction factors > 6 against MRSA and MSSA after 30s. Diluted disinfectants (50%) were significantly less effective against MRSA at short reaction times (15 s) (p < 0.05). Sterillium in a dilution of 50% did not reach 5 reduction factors against either MRSA or MSSA after 30 s. The impact of an appropriate use of hand disinfectants in order to break chains of infections with MRSA is obvious.

1-Propanol↗
PubMed1997

[Hygiene in the surgical department--recommendations by the National Reference Center for Hospital Hygiene].

Many hygienic procedures performed in operation units are not supported by scientific investigations. The following recommendations by the National Reference Center for Hospital Epidemiology, founded by the German Ministry of Health in 1996, are based on the scientific literature and separate necessary from less necessary and unnecessary procedures.

Centers for Disease Control and Prevention, U.S.↗
PubMed1997

An analysis of two prevalence surveys of nosocomial infection in German intensive care units.

In 1995, the results of two extensive prevalence studies on hospital-acquired infections were published. Both studies included a prevalence component for German intensive care units (ICUs), but provided very different infection rates. A comparison of the methods used revealed that the data from the ICUs included in the German section of EPIC (European Prevalence of Infection in Intensive Care), reflected the situation in the ICUs of large hospitals. The situation in ICUs with fewer than 600 beds was quite different, and led to the lower overall rate of infection as seen in the NIDEP (Nosocomial Infections in Germany-Surveillance and Prevention) study. Additionally, the NIDEP data permitted the calculation of device-associated, device-day, infection rates for urinary tract infections, pneumonia and bacteraemia. The differences between the ICUs in the two hospital groups were mainly due to a lower use of patient devices with regard to urinary catheters, central venous lines and respiratory ventilators.

Bacteremia↗
PubMed1997

Analysis of risk factors for nosocomial infections--results from the first national prevalence survey in Germany (NIDEP Study, Part 1).

An analysis of risk factors for nosocomial infections (NI) was carried out using data from the first national prevalence survey on NI in Germany. Fourteen thousand, nine hundred and sixty-six patients, with a total of 543 NI, were included. Urinary tract infections (UTI), lower respiratory tract infections (LRTI), surgical site infections (SSI) and primary septicaemia (PS) were analysed. UTI were significantly associated with unconsciousness, age, prior operation, hospital size and female sex (P < 0.1). LRTI were significantly associated with chronic airway disease, intensive care units, unconsciousness, polytrauma, prior operation, cardiovascular disease, malignancy and absence of infection on admission. The department, age, diabetes mellitus, male sex and hospital size were risk factors for SSI. The department, prior operation and unconsciousness were significantly associated with PS. An investigator effect was observed for LRTI and PS. Although no final conclusions from a risk factor analysis based on prevalence data can be drawn the results support stratification of NI for routine surveillance.

Adult↗
PubMed1997

Survival of Acinetobacter baumannii on dry surfaces.

Acinetobacter spp. have frequently been reported to be the causative agents of hospital outbreaks. The circumstances of some outbreaks demonstrated the long survival of Acinetobacter in a dry, inanimate environment. In laboratory experiments, we compared the abilities of five Acinetobacter baumannii strains, three Acinetobacter sp. strains from the American Type Culture Collection (ATCC), one Escherichia coli ATCC strain, and one Enterococcus faecium ATCC strain to survive under dry conditions. Bacterial solutions of the 10 strains were inoculated onto four different material samples (ceramic, polyvinyl chloride, rubber, and stainless steel) and stored under defined conditions. We investigated the bacterial counts of the material samples immediately after inoculation, after drying, and after 4 h, 1 day, and 1, 2, 4, 8, and 16 weeks of storage. A statistical model was used to distribute the 40 resulting curves among four types of survival curves. The type of survival curve was significantly associated with the bacterial strain but not with the material. The ability of the A. baumannii strains to survive under dry conditions varied greatly and correlated well with the source of the strain. Strains isolated from dry sources survived better than those isolated from wet sources. An outbreak strain that had caused hospital-acquired respiratory tract infections survived better than the strains from wet sources, but not as well as strains from dry sources. Resistance to dry conditions may promote the transmissibility of a strain, but it is not sufficient to make a strain an epidemic one. However, in the case of an outbreak, sources of Acinetobacter must be expected in the dry environment.

Acinetobacter↗
PubMed1997

[Sick building syndrome and HVAC system: MVOC from air filters].

Growth and emissions of volatile metabolites of microorganisms on air filters are suspected to contribute to health complaints in ventilated rooms. To prove the microbiological production of volatile organic compounds (MVOC), concentrations of aldehydes and ketones were determined in two large HVAC systems. The in situ derivated aldehydes and ketones (as 2,4-dinitrophenyl-hydrazones) were analysed by HPLC and UV detection. The detection limit of each compound was 1 ppb (margin of error < 10%). Field measurements were carried out before and after the prefilters and the main filters, respectively, to investigate whether aldehydes and ketones increase in concentration after filters of HVAC systems. First results show that the compounds formaldehyde, acetaldehyde and acetone could be detected before and after the filters. The concentrations of these VOC after the filters were significantly increased--as a mean over twenty measurements--, especially as far as filters made of glass fibre are concerned. However the found concentrations were low and mostly comparable to outdoor findings. In simultaneous laboratory experiments pieces of used filter material of one HVAC system and unused filter pieces (for blank values) were examined in small incubation chambers to investigate the possible production of MVOC. For the incubation a temperature of 20 degrees C and a relative humidity of 95% was chosen. In these experiments an almost identical spectrum of compounds (formaldehyde and acetone) was found as in the field measurements. The concentrations of these compounds were higher in the chambers with the used filter pieces. The concentration of acetone ranged up to almost 12 mg/m3.--As our field experiments correspond with our laboratory experiments, we assume that the microbial production of volatile organic compounds in HVAC systems under operating conditions is possible.

Air Microbiology↗
PubMed1996

[Nosocomial infections in Germany. Microbiological diagnosis, preventive antibiotics and antibiotic therapy].

BACKGROUND: The NIDEP-study (Nosocomial Infections in Germany-Prevalence and Prevention) is the first large multicenter survey to examine the prevalence of nosocomial infections (NI) in Germany. This part of the NIDEP-study describes the frequency and quality of the microbiological diagnosis, antimicrobial chemoprophylaxis and therapy in representative German hospitals. PATIENTS AND METHOD: Prevalence of nosocomial infections in 14 966 patients of 72 randomly selected representative German hospitals was determined. Frequency, nature and results of the microbiological diagnosis, antimicrobial chemoprophylaxis and therapy were recorded simultaneously. RESULTS: The total prevalence rate of nosocomial infections was 3.5%. The most common infections were urinary tract infections (42.1%), lower respiratory tract infections (20.6%), postoperative wound infections (15.8%), and septicemia (8.3%). Microbiological evaluation was done in 56.5% of the patients with infections. Only five of the 49 hospitals with less than 400 beds and only nine of the 23 hospitals with more than 400 beds had their own microbiological department. Antimicrobial chemotherapy was administered in 17.7% of the patients. In 35.1% of the patients who were treated with antibiotics, no clinical diagnosis of infection was made, criteria for nosocomial infections were not fulfilled or microbiological evaluation was not established. Antimicrobial chemoprophylaxis was done in one third of the patients. Prophylaxis was missed in 20.6% of patients with colorectal operations, 60.1% of appendectomies, 48% of vaginal hysterectomies, and 35.5% of total hip replacements. On the other hand antimicrobial chemoprophylaxis was frequently administered in clean procedures without increased risk of postoperative wound infections. CONCLUSION: Insufficient microbiological evaluation, inadequate perioperative antimicrobial chemoprophylaxis and administration of chemotherapy without documented infection were detected in representative German hospitals.

Anti-Bacterial Agents↗
PubMed1996

[Nosocomial infections in Germany. Their epidemiology in old and new Federal Länder].

OBJECTIVE: To determine the prevalence rate of nosocomial infections in different parts of Germany. PATIENTS AND METHODS: The study involved 14,966 patients (45.9% medical, 35.9% surgical, 14.7% obstetrical/gynaecological and 3.5% intensive care) in 72 randomly chosen German hospitals (59 in the old [i.e. previously West German] and 13 in the new [i.e. East German] Federal Lands). Using the CDC criteria for the diagnosis of nosocomial infections specially trained doctors determined whether the infection was in fact nosocomial. RESULTS: There was a 3.5% prevalence rate of nosocomial infections in the entire population (95% confidence interval 3.1-3.9%). In view of the chosen methods and the in part incorrect indication of microbiological diagnosis in the included hospital, this rate of nosocomial infection is likely to be a minimum number. The prevalence rate for the most important nosocomial infections was lower in the new Lands of Federal Germany than the older ones (total prevalence of 2.7 vs 3.6%). The difference is mainly due to the less frequent employment of various devices (e.g. peripheral vascular catheters), rather than different hygienic standards in their use. CONCLUSION: The lower prevalence rate of nosocomial infections in the new Lands, because fewer devices are employed, underlines the need constantly to test the indications for their use.

Adult↗
PubMed1996

Microbiological contamination of drinking water in a commercial household water filter system.

The microbiological quality of filtered water in a commercial water filter system (Brita) was tested in households and in two laboratories. In 24 of 34 filters used in households, bacterial counts increased in the filtered water up to 6,000 cfu/ml. In 4 of 6 filters tested in the laboratory, bacterial counts in the fresh filtrate were higher than in tap water after approximately one week of use both at room temperature and at 4 degrees C, suggesting growth or biofilm formation in the filter material. In some cases colony counts in the filtered water were 10,000 times those in tap water. The filter material of 5 of 13 new commercial filters was contaminated with bacteria or moulds. National or international regulatory agencies should ensure that water filters marketed for domestic use do not allow deterioration in the microbiological quality of drinking water.

Bacteria↗
PubMed1996

[Nosocomial infections intensive care units. A nation-wide prevalence study].

UNLABELLED: In a large, multicenter survey in 1994, the prevalence of nosocomial infections in German hospitals was examined, predominant pathogens were identified, and possible risk factors evaluated. In this paper the results from the intensive care units (ICUs) are presented. METHODS: Seventy-two representative hospitals in Germany were selected by randomisation and divided into four different groups according to their size (< 200 beds; 200-400 beds; 400-600 beds; > 600 beds). During 10 months four especially trained doctors documented the patients clinical and laboratory data and possible endogenous and exogenous risk factors for nosocomial infections. For better evaluation, they discussed the cases with the responsible senior officers and health care workers and visited the patients. Diagnosis of nosocomial infection was based on CDC criteria. RESULTS: In 515 patients in 89 ICUs, 78 hospital-acquired infections were documented (15.3%). The most common were pneumonia (5.9%), bronchitis (2.7%), urinary tract infections (2.4%), and septicaemia (2.2%). Possible exogenous risk factors included: peripheral venous catheters (65.6%); catheterisation of the urinary tract (64.5%); central venous catheters (60.4%); gastric tubes (38.0%); wound drainage (28.6%) and artificial ventilation (27.6%). The most frequent concomitant diseases were cardiovascular (61.9%), diabetes (20.2%), malignancies (18.8%), pre-existing infections (15.3%), and chronic respiratory disease (14.0%). The prevalence of nosocomial infections was higher in hospitals with more than 600 beds than in smaller ones (28.3% versus 12.9%, P < 0.001). Predominant pathogens were Pseudomonas aeruginosa, enterococci, Staphylococcus aureus, Candida spp., Escherichia coli, and Klebsiella spp.. Fifty per cent of the ICUs changed ventilation tubes and 66.3% changed infusion sets daily; 34.8% of patients received drugs for the prevention of stress ulcers that neutralise or decrease production of gastric acid; only 7.6% received sucralfate. Routine microbiological surveillance of tracheal aspirates and urine was done by 25.9% and 24.6% of the ICUs, respectively. DISCUSSION: Nosocomial infections are seen far more often in ICUs than on normal wards due to the immuno-suppressed state of many ICU patients and the continuous use of invasive diagnostic and therapeutic procedures. Most of these infections are of endogenous origin. Other prevalence surveys have shown results comparable to ours. Daily changing of ventilation tubes is no longer necessary, but is still routine in many hospitals. Infusion sets were also changed more often than required. The use of selective decontamination of the digestive tract for the prevention of pneumonia is still controversial; in our study it was practised in only 1.5% of the cases. The most commonly used drugs for the prevention of stress ulcers were H2-receptor blocking agents, although it has been shown that sucralfate is the better choice, as it can help prevent nosocomial pneumonia. Routine microbiological surveillance of tracheal aspirates and urine was done in 25.9% and 24.6% of the ICUs. No study so far has shown that routine cultures of tracheal secretions and urine have a preventive effect regarding infection.

Adult↗
PubMed1996

[Hospital infections in gynecology and obstetrics. An inclusive prevalence study in Germany].

In a German multicenter survey, 2206 gynaecological patients in 72 randomly selected hospitals were examined for the prevalence of nosocomial infections and possible risk factors. Hospital-acquired infections were diagnosed in 1.45% of the patients. The most common localisation was the urinary tract (0.91%). Septicaemia, vaginitis and infections of the upper and lower airways were only rarely seen. The following endogenous risk factors were identified: diseases of the cardiovascular system (16.1%), malignancies (12.2%) preexisting infections (6.1%), obesity (5.9%), and diabetes (5.0%). The most common exogenous risk factors were peripheral venous catheters (19.9%), catheterisation of the urinary tract (7.2%) and wound drainage (28.6%). 49% of the patients who underwent caesarean section and 50% of the hysterectomy patients received antimicrobial chemoprophylaxis.

Adult↗