Biomedical subjects
Publications and source records attributed to H Rüden.
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The incidence of catheter-associated primary bloodstream infections (BSIs) in Germany as defined by the CDC (Centers for Disease Control) has been determined on the basis of (a) a national prevalence study in a representative sample of 72 hospitals (NIDEP), and (b) an incidence study in which data about the use and duration of insertion of central venous catheters (CVC) and of catheter-associated BSI were collected from 25 intensive-care units (ICUs) participating in the hospital infection surveillance system (KISS+) and analyzed. The first study showed primary bloodstream infection to be the fourth most frequent nosocomial infection at 8.3% of all nosocomial infections. With an ICU prevalence of 2.1%, primary BSI comprises 12.8% of all nosocomial infections observed in ICU patients. The second study showed a 60.4% prevalence of CVC use in German ICUs. An analysis of 55,400 CVC days in 14,988 ICU patients in the KISS hospitals yielded 2.2 CVC-associated BSIs per 1,000 CVC days (CI95 1.8-2.6). The rates of CVC-associated BSI on individual hospital wards were very variable and indicates a reduction potential. A reduction in the number of infections of about one-third would prevent 1,000-1,400 deaths due to CVC-associated BSI annually as well as about 40,000 to 60,000 extra days of hospital stay and the associated costs.
Nosocomial infection (NI) was prospectively studied in hospitalized neonates during a 10-month period. The Centers for Disease Control (CDC) criteria (some specified for neonates) were used for surveillance. Forty-nine of 677 infants experienced 73 episodes of NI. The overall incidence was 10.8 NI/100 patients and 6.5 NI/1,000 patient days. The average monthly NI number did not correlate with patient load. Very low birth weight (VLBW) infants showed a higher NI incidence (81.8 NI/100 patients and 11.1 NI/1,000 patient days), also elevated if adjusted for their inherently longer neonatal intensive care unit (NICU) stay. The most common NI sites in the VLBW stratum were sepsis and necrotizing enterocolitis (NEC), the latter occurring in a seasonal cluster. It can be concluded that surveillance for NIs should focus on VLBW infants and include the evaluation of NEC, as it behaves like a nosocomial disease.
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Nosocomial infections (NI) are a major problem, and numerous measures are being recommended for preventing NIs in Germany. However, the evidence for the efficacy of many currently recommended measures is incomplete or has been established for certain sub-groups of patients or specific conditions only. In view of this situation, it is necessary to improve the established measures for preventing NIs. Since many procedures and components of infection control involve additional expenditure, their deployment can only be justified if their efficiency has been demonstrated or is highly likely on the basis of rational considerations.
OBJECTIVE: To investigate how many nosocomial infections would be missed if surveillance activities were restricted to patients having either microbiology reports or antibiotic administration. DESIGN: Analysis of data from a large prevalence study on nosocomial infections (Nosocomial Infections in Germany-Surveillance and Prevention). SETTING: A total of 14,966 patients were investigated in medical, surgical, obstetric-gynecologic, and intensive-care units of 72 German hospitals representatively selected according to size. Five hundred eighteen patients (3.5%) had at least one nosocomial infection. Microbiology reports were available for 56.6% of these patients on the prevalence day, and 86.3% received antibiotics. RESULTS: Only 31 nosocomially infected patients (6%) would have been missed by using either microbiology reports or antibiotic treatment as an indicator. These indicators of nosocomial infections had a high diagnostic sensitivity for nosocomial pneumonia (98.8%), urinary tract infections (96.3%), and primary bloodstream infections (95.3%), but a lower sensitivity for wound infections (85.4%). Thus, 97.4% of all nosocomial infections were found with this method in intensive-care units and 96.1% in medicine units, but only 89.7% in surgical departments. In 9 (12.5%) of 72 hospitals, the overall sensitivity would have been <80% using a combination of the two indicators. For this reason, the situation in one's own hospital should be checked before using this method. CONCLUSIONS: After checking the situation in one's own hospital, the "either-or" approach using the two indicators "microbiology report" and "antibiotic administration" can be recommended as a time-saving measure to diagnose pneumonia, urinary tract, and primary bloodstream infections. For wound infections, additional information obtained by changing dressings or participating in ward rounds is necessary to achieve satisfactory sensitivity in the surveillance of nosocomial infections. Of course, it is necessary that the surveillance staff discard all false positives to ensure a satisfactory specificity.
AIMS: To evaluate the BBL Crystal MRSA ID System for detection of oxacillin resistance in Staphylococcus aureus. METHODS: 52 methicillin resistant S aureus (MRSA) from five different countries and 85 methicillin susceptible S aureus (MSSA) were included. The species was confirmed by tube coagulation and detection of the clumping factor using the Staphaurex Plus. Clonal non-identity of the MRSA isolates was shown by pulsed field gel electrophoresis. MIC values (oxacillin) were determined using the Etest. Polymerase chain reaction was carried out to detect the mecA gene. The BBL Crystal MRSA ID System was carried out according to the manufacturer's instructions. RESULTS: The BBL Crystal MRSA ID System showed fluorescence in 45 of 52 MRSA (sensitivity 86.5%; negative predicitive value 92.2%), and the specificity was 97.6% (positive predicitive value 95.7%). Two of seven MRSA that failed to show fluorescence had MIC values (oxacillin) of 4 mg/litre. CONCLUSIONS: The BBL Crystal MRSA ID System is a valuable test for detecting oxacillin resistance in S aureus. Its major advantage is the short time (4-5 hours) required to perform the test when organisms are grown on tryptic soy agar or sheep blood agar. Difficulties may arise in borderline resistant isolates.
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Aseptic operations as well as operations on infected sites can be done in the same operating room. Two or more theatres can share common facilities such as X-ray equipment, scrub-up or anaesthesia areas. Sophisticated air locks with double doors, which separate the protective zone from the operating room are not necessary to maintain a good hygienic standard. Nevertheless the new requirements for theatre design by the German "Gesetzliche Unfallversicherungen" are much higher. In this commentary we try to summarize scientific evidence regarding design of a theatre and infection control.
Hand disinfectants containing chlorhexidine are thought to be less bactericidal against methicillin-resistant Staphylococcus aureus (MRSA) than methicillin-susceptible Staphylococcus aureus (MSSA). We report an in vitro comparison between three distinct MRSA strains and three MSSA strains. The bactericidal efficacy of chlorhexidine digluconate, 'Hibiscrub' and 'Hibisol' against Staphylococcus aureus was determined in a quantitative suspension test. Logarithmic reduction factors (RF) were calculated for each of six parallel experiments. Chlorhexidine digluconate and 'Hibisol' showed RF > 5 at most concentrations and reaction times but 'Hibiscrub' did not. MRSA was found to be significantly less susceptible than MSSA to chlorhexidine digluconate, 'Hibiscrub' and 'Hibisol' (P < 0.05; two-tailed t-test for independent samples). 'Hibisol' was significantly more effective against MRSA than 'Hibiscrub' (P < 0.05). Hand disinfectants containing both alcohol and chlorhexidine (e.g., 'Hibisol') are more effective against MRSA than scrubs based only on chlorhexidine ('Hibiscrub') and should be used in clinical practice.
The nosocomial infection (NI) rate in German hospitals was studied in order to create reference data for comparison in hospitals where ongoing surveillance is impossible. The study was designed as a one-day prevalence study. Patients in 72 selected hospitals (inclusion criteria: acute care hospitals with departments for general medicine, surgery, obstetrics/gynaecology) were examined by four external investigators (physicians trained and validated in the diagnosis of NI). A total of 14,996 patients were studied. The overall prevalence rate was 3.5% (CI 3.1-3.9) with a variation of 0-8.9% between hospitals. The commonest NI were: urinary tract infection (42.1%), lower respiratory tract infection (20.6%), surgical site infections (15.8%) and primary sepsis (8.3%). The highest prevalence rate (15.3%) was found in intensive care ward patients, followed by surgery (3.8%), general medicine (3.0%) and gynaecology/obstetrics (1.4%). The infection rate varied significantly with hospital size. A microbiology laboratory report was only available for 56.5% of patients thought to have an NI, and there were remarkable differences between hospitals with and without an on-site microbiology laboratory. Because of this and other methodological reasons the NI prevalence rates reported here may represent the absolute minimum of nosocomially infected patients in Germany.
Agreement on criteria for defining nosocomial infections is essential when surveillance is intended for quality assurance. The CDC criteria for patients < 12 months old were compared with locally developed criteria for neonates in a 10-month study of nosocomial infections in a Berlin University hospital. Six hundred and seventy-seven neonates were observed prospectively for 11,936 patient days. The overall nosocomial infection incidence rate was 13.2%. Because of the observed strength of agreement between the CDC and local criteria for central line-associated primary bloodstream infections and for ventilator-associated pneumonias (recommended by the NNIS system for inter-hospital comparisons) and the preference of the clinicians for the local criteria, we decided to use the latter for an ongoing surveillance system which nonetheless would retain the possibility for comparison with NNIS-data.
The prevalence of noncentral and central lines and the prevalence of nosocomial primary bloodstream infections was investigated in 72 representative German hospitals (NIDEP Study). Data from a total of 14,966 patients were documented. On the prevalence day, it amounted to 23.9% for noncentral and 5.1% for central lines. The total prevalence of nosocomial primary bloodstream infections was 0.3%, 8.3% of all nosocomial infections recorded were primary bloodstream infections. The device utilization rate of vascular catheters was retrospectively observed for both the prevalence day and another 6 days. The device utilization rate was 27.3% for peripheral and 6.1% for central catheters with higher rates in west Germany. The associated incidence density of primary nosocomial bloodstream infections per 1000 catheter-days was 0.3 for noncentral and 0.8 for central lines. In 61.4%, the primary bloodstream infections were microbiologically confirmed. In 52.6% of cases, Gram-positive bacteria were isolated (Staphylococcus aureus: 15.8%, other coagulase negative Staphylococcus species: 34.2%) and in 47.4%, Gram-negative ones (mostly: Escherichia coli: 13.2% and Klebsiella species: 10.5%). Prevention to reduce nosocomial bloodstream infections is possible by antimicrobial establishing specially trained infusion therapy teams, using antimicrobial or antiseptic impregnated bloodstream catheters and a strict review of the indication for a vascular catheter together with a minimization of catheter days.
OBJECTIVE: To demonstrate the limits of comparison of national prevalence rates of nosocomial infections. DESIGN AND SETTING: Critical analysis of prevalence rates and methods of the Nosocomial Infections in Germany (NIDEP) study and other prevalence surveys with particular attention to the selection of patients, the qualification and training of the investigators, and the methods of identifying nosocomial infections. RESULTS: The lowest prevalence rate was found in Germany (3.5%), the highest in Belgium (9.3%). These differences may not be accurate, because variations in methods allow for differing explanations. CONCLUSIONS: Because of numerous methodological factors, comparison of infection rates between countries should be avoided. In contrast to other prevalence studies, the methodology of the German-NIDEP study permits registration of only certain infections, which is the main reason for the low rate.
OBJECTIVE: To determine whether an investigator effect remained on the first German study on the prevalence of nosocomial infections Nosokomiale Infektionen in Deutschland Erfassung und Prävention (NIDEP), despite extensive validation efforts. DESIGN: Two validation methods were applied: bedside validation and validation by case studies. In both cases, the results of the four investigators were compared with the diagnosis of gold standard observers. SETTING: Validation measures were applied before, intermittently, during, and at the end of the surveillance period in 72 acute-care hospitals with 14,966 patients. RESULTS: The overall sensitivity in the bedside-validation periods was 89.0%; the overall specificity was 99.5%. For validation by case studies, overall sensitivity was 95.6%, and overall specificity was 92.8%. At the end of the surveillance, a remarkable investigator effect was found. CONCLUSION: Despite validation results that were assessed as satisfactory, based on available literature, an investigator effect was observed. This underlines the need for data validation and the formulation of recommendations for data validation. Clarification of the Centers for Disease Control and Prevention criteria for pneumonia and primary bloodstream infection and the inclusion of some diagnostic test results may reduce or prevent an investigator effect in future studies.
We compared the abilities of Enterococcus faecium strains (three vancomycin-resistant enterococci [VRE] and five vancomycin-susceptible enterococci [VSE]) and Enterococcus faecalis strains (one VRE and 10 VSE) to survive under dry conditions. Bacterial suspensions of the strains were inoculated onto polyvinyl chloride and stored under defined conditions for up to 16 weeks. All strains survived for at least 1 week, and two strains survived for 4 months. A statistical model was used to distribute the 19 resulting survival curves between two types of survival curves. The type of survival curve was not associated with the species (E. faecalis versus E. faecium), the source of isolation (patient versus environment), or the susceptibility to vancomycin (VRE versus VSE). Resistance to dry conditions may promote the transmissibility of a strain, but VRE have no advantages over VSE with respect to their ability to survive under dry conditions.
Mannitol salt agar was evaluated for detection of oxacillin resistance in 136 Staphylococcus aureus isolates. All mecA-positive isolates (n = 54) were correctly categorized as oxacillin resistant by the disk diffusion test (1-microgram disk; zone diameter, < 16 mm); the specificity was 97.6%. Agar screening (2 micrograms of oxacillin per ml) revealed a sensitivity of 98.1% and a specificity of 95.1%.