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K Weist

Publications and source records attributed to K Weist.

At least 19 recordsLinked to original sources
PubMed2007

[Prevention and control of the spread of vancomycin-resistant enterococci: results of a workshop held by the German Society for Hygiene and Microbiology].

The incidence of vancomycin-resistant enterococci (VRE), especially E. faecium, is increasing in several German hospitals and some facilities have experienced VRE outbreaks. The German National Nosocomial Infection Surveillance System has also noticed a sharp increase in the incidence of nosocomial VRE infections per 10,000 patients from 0.5 in 2003 to 11.0 in 2005 accompanied by a rise in VRE-associated mortality. However, the reasons of this increase remain unknown. As VRE may cause severe nosocomial infections, transmission must be restricted. This article provides the guidelines as defined by the workshop of the German Society for Hygiene and Microbiology for the prevention of VRE transmission in both, endemic and epidemic, settings. The following topics are discussed: indication for VRE screening, microbiological diagnostics, general infection control measures (isolation precautions and use of protective clothing) and additional hygiene measures in the nosocomial VRE outbreak setting.

Cross Infection↗
PubMed2006

[Control of methicillin-resistant S. aureus by active surveillance. Results of a workshop held by the Deutsche Gesellschaft für Hygiene und Mikrobiologie].

In Germany, methicillin-resistant S. aureus (MRSA) is increasing continuously. To control the spread of MRSA, active surveillance and admission screening are recommended. In most cases, screening cultures of patients at risk for MRSA will be sufficient. Screening of all patients admitted to an ICU is cost-effective when the incidence of MRSA and nosocomial MRSA infections is high (>2 cases/100 patients and 0.3 MRSA infections/100 patients, respectively): Under these circumstances, a decrease in the incidence of nosocomial MRSA infections of 50% leads to cost-effectiveness at costs of 16 Euro/sample (including subsequent costs). If the incidence of nosocomial MRSA infections decreases by 75%, costs of 24 Euro/sample (including subsequent costs) are cost-effective. If the incidence of MRSA is high, screening by PCR may be cost-effective for patients at high risk for MRSA, especially if they are isolated prophylactically. Recently, PCR methods have been developed which allow the specific identification of MRSA even from nasal swabs.

Cost-Benefit Analysis↗
PubMed2005

[Incidence of transmission of pathogens in intensive care units. Results of the SIR 3 study].

The objective of this study was to determine the incidence of episodes of transmission of nosocomial pathogens and of those pathogens leading to nosocomial infections. Over a period of 18 months all patients from 5 intensive care units (ICUs) who stayed for more than 2 days were included in this study. Surveillance of nosocomial infections was carried out and all isolates of 10 of the most frequent pathogens in ICUs (indicator pathogens) were collected and typed. A total of 28,498 patient days and 431 nosocomial infections were observed (incidence density 15.1 per 1,000 patient days), among them 278 caused by 1 of the selected indicator pathogens. A total of 141 episodes of transmissions were identified, corresponding to an incidence of episodes of transmission of 5.0 per 1,000 patient days and 41 nosocomial infections were transmission-associated, corresponding to 14.5% of all nosocomial infections. The data of this study demonstrate that even in ICUs with average nosocomial infection rates, some nosocomial infections could be avoided.

Anesthesia↗
PubMed2005

Effectiveness of a hospital-wide selective screening programme for methicillin-resistant Staphylococcus aureus (MRSA) carriers at hospital admission to prevent hospital-acquired MRSA infections.

Screening of potential MRSA-positive patients at hospital admission is recommended in German and international guidelines. This policy has been shown to be effective in reducing the frequency of nosocomial MRSA transmissions in the event of an outbreak, but the influence of screening on reducing hospital-acquired MRSA infections in a hospital setting where MRSA is endemic is not yet well-documented. This study describes the effect of hospital-wide screening of defined risk groups in a 700-bed acute care hospital during a period of 19 months. In a cohort study with a 19-month control period, the frequencies of hospital-acquired MRSA infections were compared with and without screening. In the control period, there were 119 MRSA-positive patients, of whom 48 had a hospital-acquired MRSA infection. On the basis of this frequency, a predicted total of 73.2 hospital-acquired MRSA infections was calculated for the screening period, but only 52% of the expected number (38 hospital-acquired MRSA infections) were observed, i.e., 48% of the predicted number of hospital-acquired MRSA infections were prevented by the screening programme. The screening programme was performed with minimal effort and can therefore be recommended as an effective measure to help prevent hospital-acquired MRSA infections.

Aged↗
PubMed2003

Inducibility and potential role of MecA-gene-positive oxacillin-susceptible Staphylococcus aureus from colonized healthcare workers as a source for nosocomial infections.

To determine the carrier rate of methicillin-susceptible mecA-positive Staphylococcus aureus (dormant MRSA) among healthcare workers (HCWs), 447 nurses and physicians from 13 general wards and intensive care units were investigated for nasal or oropharyngeal S. aureus carriage during one year whenever an MRSA patient was treated. Induction of phenotypic resistance in all mecA-positive oxacillin-susceptible aureus was attempted by 24 h exposure to oxacillin and cefotaxime. Organisms from the broth tube with the highest antibiotic concentration and visible growth after incubation were re-exposed for a total of seven repetitive exposures. Two mecA-negative oxacillin-susceptible S. aureus served as negative control. A population analysis before and after antibiotic exposure was performed. A third of the HCWs were found to be S. aureus carriers. Only three nurses were MRSA positive (0.7%). Seven isolates of dormant MRSA were isolated in six nurses and one doctor (1.6%). After four days of repetitive antibiotic exposure six of seven dormant MRSA were highly resistant to oxacillin. Resistance of the two control S. aureus without the mecA gene was not changed by repetitive antibiotic exposure. Two of the seven dormant MRSA were clonally related as shown by pulsed-field gel electrophoresis (PFGE). The PFGE pattern of one dormant MRSA (HCW) was identical to an MRSA (HCW). The pattern of another dormant MRSA was indistinguishable from an MRSA isolated from a patient who was treated at the same time on the same ward suggesting transmission from the HCW to the patient. Dormant MRSA may be isolated twice as often as MRSA from HCWs. Transmission to patients is possible, which may lead to clinical infections. It might be useful to screen methicillin-susceptible S. aureus isolates from HCWs for the mecA gene when recurrent infections with MRSA occur on a ward and a source cannot be found.

Bacterial Proteins↗
PubMed2003

Comparison of PCR-based methods for typing Escherichia coli.

OBJECTIVE: To establish a library typing system appropriate for studying cross-transmission of Escherichia coli. METHODS: Eighteen epidemiologically unrelated isolates were genotyped by means of pulsed-field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), repetitive (rep) PCR, and fluorescent amplified fragment length polymorphism (AFLP). Fingerprints were analyzed either by Pearson correlation or, in the case of AFLP, by Dice coefficients employing the novel 'uncertain band' software tool from GelCompar II. During a nine-month period, 112 isolates taken from 93 patients hospitalized in five intensive care units were analyzed by use of the two most discriminative PCR typing methods. RESULTS: Genotyping by RAPD and rep-PCR revealed insufficient discrimination. Among 18 epidemiologically unrelated strains with 17 different PFGE patterns, IS3 rep-PCR and AFLP distinguished 10 and 18 types, respectively. Comparison of the different methods for analysis of AFLP fingerprints showed that the Dice coefficients, which ignore 'uncertain bands', offered the best concordance with visual interpretation. Consecutive isolates originating from the same patient differed in less than three fragments. CONCLUSIONS: AFLP analysis showed the highest discriminative capacity for PCR typing of E. coli isolates. Analysis of fingerprints employing the Dice coefficients proved the most efficient method for an automated software-based retrieval of visually indistinguishable genotypes in an AFLP fingerprint database.

Bacterial Typing Techniques↗
PubMed2001

[Infections caused by Stenotrophomonas maltophilia (SMA) in intensive care patients--a prospective case-control study].

BACKGROUND AND OBJECTIVE: The importance of Stenotrophomonas maltophilia (SMA) as an etiologic frequently polyresistant pathogen in severe nosocomial infections has increased. METHODS: In our prospective study we evaluated the risk factors of nosocomial infections by SMA in our internal intensive care unit (ICU) over a one year period from July 1997 to June 1998. RESULTS: 111 patients (80 men, 31 women, mean age +/- SD: 58.0 +/- 13.3 years) were treated for more than 5 days in the ICU. SMA were cultured in 16/111 patients (13 men, three women, mean age 57.8 +/- 3.4 years) out of bronchial secretions (68%), sputum (19%) and pleural fluid (13%). Univariate analysis resulted in 15 different risk factors (p < 0.05); however, multivariate analysis provided three independent risk factors: chronic obstructive pulmonary disease (OR 95% CI [1.91; infinity]), length of stay in the ICU (OR 95% CI [1.07; 1.26]) and therapy with carbapenems before admittance to ICU (OR 95% CI [0.56; 153]). Four of 16 patients died due to an SMA-infection, two by purulent exacerbations of a chronic bronchitis and two by sepsis. Molecular typing of 18 SMA isolates in 15 patients resulted in 9 different genetic types and a clonal dissemination could only be confirmed in three patients. CONCLUSIONS: In respiratory ICU SMA infections are favored by severe COPD, length of stay in the ICU and by selection pressure of applicated antibiotics, especially carbapenems.

APACHE↗
PubMed2000

An outbreak of pyodermas among neonates caused by ultrasound gel contaminated with methicillin-susceptible Staphylococcus aureus.

OBJECTIVE: To investigate an outbreak of methicillin-susceptible Staphylococcus aureus (MSSA) infections in a neonatal clinic. DESIGN: Prospective chart review, environmental sampling, and genotyping by two independent methods: pulsed-field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR). A case-control study was performed with 31 controls from the same clinic. SETTING: A German 1,350-bed tertiary-care teaching university hospital. RESULTS: There was a significant increase in the incidence of pyodermas with MSSA; 10 neonates in good physical condition with no infection immediately after birth developed pyodermas. A shared spatula and ultrasound gel were the only identified infection sources. The gel contained MSSA and was used for hip joint sonographies in all neonates. PFGE and RAPD-PCR patterns from 6 neonates and from the gel were indistinguishable and thus genetically related clones. The case-control study revealed no significant risk factor with the exception of cesarean section (P=.006). The attack rate by days of hip-joint sonography between April 15 and April 27, 1994, was 11.8% to 40%. CONCLUSIONS: Inappropriate hygienic measures in connection with lubricants during routine ultrasound scanning may lead to nosocomial S. aureus infections of the skin. To our knowledge this source of S. aureus infections has not previously been described.

Case-Control Studies↗
PubMed1999

Catheter-associated primary bloodstream infections: epidemiology and preventive methods.

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.

Catheterization, Central Venous↗
PubMed1999

Evaluation of the BBL Crystal MRSA ID System for detection of oxacillin resistance in Staphylococcus aureus.

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.

Evaluation Studies as Topic↗
PubMed1998

Evaluation of mannitol salt agar for detection of oxacillin resistance in Staphylococcus aureus by disk diffusion and agar screening.

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%.

Culture Media↗
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↗
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↗