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Andreas F Widmer - One of the best experts on this subject based on the ideXlab platform.
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Variability in Contact precautions to control the nosocomial spread of multi-drug resistant organisms in the endemic setting: a multinational cross-sectional survey.
Antimicrobial Resistance and Infection Control, 2018Co-Authors: Danielle Vuichard Gysin, Barry Cookson, Henri Saenz, Markus Dettenkofer, Andreas F WidmerAbstract:Definitions and practices regarding use of Contact precautions and Isolation to prevent the spread of gram-positive and gram-negative multidrug-resistant organisms (MDRO) are not uniform. We conducted an on-site survey during the European Congress on Clinical Microbiology and Infectious Diseases 2014 to assess specific details on Contact precaution and implementation barriers. Attendants from 32 European (EU) and 24 non-EU countries participated (n = 213). In EU-respondents adherence to Contact precautions and Isolation was high for Methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Enterobacteriaceae, and MDR A. baumannii (84.7, 85.7, and 80%, respectively) whereas only 68% of EU-respondents considered any Contact precaution measures for extended-spectrum-beta-lactamase (ESBL) producing non-E. coli. Between 30 and 45% of all EU and non-EU respondents did not require health-care workers (HCW) to wear gowns and gloves at all times when entering the room of a patient in Contact Isolation. Between 10 and 20% of respondents did not consider any rooming specifications or Isolation for gram-positive MDRO and up to 30% of respondents abstain from such interventions in gram-negative MDRO, especially non-E. coli ESBL. Understaffing and lack of sufficient Isolation rooms were the most commonly encountered barriers amongst EU and non-EU respondents. The effectiveness of Contact precautions and Isolation is difficult to assess due to great variation in components of the specific measures and mixed levels of implementation. The lack of uniform positive effects of Contact Isolation to prevent transmission may be explained by the variability of interpretation of this term. Indications for Contact Isolation require a global definition and further sound studies.
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rate of transmission of extended spectrum beta lactamase producing enterobacteriaceae without Contact Isolation
Clinical Infectious Diseases, 2012Co-Authors: Sarah Tschudinsutter, Reno Frei, Marc Dangel, Anne Stranden, Andreas F WidmerAbstract:Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are emerging worldwide. Contact Isolation is recommended; however, little is known about the rate of transmission without Contact Isolation in the non-epidemic setting. Therefore, we aimed to estimate the rate of spread (R(0)) of ESBL-producing Enterobacteriaceae in a tertiary care center with 5 intensive care units.; In this observational cohort study performed from June 1999 through April 2011, all patients at the University Hospital Basel, Switzerland, who were hospitalized in the same room as a patient colonized or infected with an ESBL-producing Enterobacteriaceae for at least 24 hours (index case) were screened for ESBL carriage by testing of rectal swab samples, swab samples from open wounds or drainages, and urine samples from patients with foley catheters. Strains with phenotypic evidence for ESBL were confirmed by polymerase chain reaction. Nosocomial transmission was assumed when the result of screening for ESBL carriage in a Contact patient was positive and molecular typing by pulsed-field gel electrophoresis (PFGE) revealed clonal relatedness with the strain from the index patient.; Active screening for ESBL carriage could be performed in 133 consecutive Contact patients. Transmission confirmed by PFGE occurred in 2 (1.5%) of 133 Contact patients, after a mean exposure to the index case of 4.3 days.; The estimated rate of spread of ESBL-producing Enterobacteriaceae-in particular, Escherichia coli-was low in a tertiary care university-affiliated hospital with high levels of standard hygiene precautions. The low level of nosocomial transmission and the rapid emergence of community-acquired ESBL challenge the routine use of Contact Isolation in a non-epidemic setting, saving resources and potentially improving patient care.
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Rate of Transmission of Extended-Spectrum Beta-Lactamase–Producing Enterobacteriaceae Without Contact Isolation
Clinical Infectious Diseases, 2012Co-Authors: Sarah Tschudin-sutter, Reno Frei, Marc Dangel, Anne Stranden, Andreas F WidmerAbstract:Extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are emerging worldwide. Contact Isolation is recommended; however, little is known about the rate of transmission without Contact Isolation in the non-epidemic setting. Therefore, we aimed to estimate the rate of spread (R(0)) of ESBL-producing Enterobacteriaceae in a tertiary care center with 5 intensive care units.; In this observational cohort study performed from June 1999 through April 2011, all patients at the University Hospital Basel, Switzerland, who were hospitalized in the same room as a patient colonized or infected with an ESBL-producing Enterobacteriaceae for at least 24 hours (index case) were screened for ESBL carriage by testing of rectal swab samples, swab samples from open wounds or drainages, and urine samples from patients with foley catheters. Strains with phenotypic evidence for ESBL were confirmed by polymerase chain reaction. Nosocomial transmission was assumed when the result of screening for ESBL carriage in a Contact patient was positive and molecular typing by pulsed-field gel electrophoresis (PFGE) revealed clonal relatedness with the strain from the index patient.; Active screening for ESBL carriage could be performed in 133 consecutive Contact patients. Transmission confirmed by PFGE occurred in 2 (1.5%) of 133 Contact patients, after a mean exposure to the index case of 4.3 days.; The estimated rate of spread of ESBL-producing Enterobacteriaceae-in particular, Escherichia coli-was low in a tertiary care university-affiliated hospital with high levels of standard hygiene precautions. The low level of nosocomial transmission and the rapid emergence of community-acquired ESBL challenge the routine use of Contact Isolation in a non-epidemic setting, saving resources and potentially improving patient care.
Roger Lewis - One of the best experts on this subject based on the ideXlab platform.
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WHEEL/RAIL Contact Isolation DUE TO TRACK CONTAMINATION
2020Co-Authors: Roger Lewis, Rob Dwyer-joyce, J LewisAbstract:An experimental study has been carried out to investigate the effect of sanding on the electrical Isolation of a wheel/rail Contact. Sand is applied to the wheel/rail interface to increase adhesion in both braking and traction. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train ‘shorting out’ the track circuit. Sand in the wheel/rail interface means that Contact between the wheelsets and the track may be compromised, inhibiting train identification. Static tests were performed using sections cut from wheels and rail and dynamic tests on a twin disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. The electrical circuit used was a simplified simulation of the TI21 track circuit. The application of sand was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the amount of sand applied, below which there is a measurable, but not severe, change in voltage, but above which the Contact conductance decreases by an order of magnitude. A model of electrical Isolation has been developed assuming either full disc separation by a sand layer or partial disc Contact with some sand present. Idealisations inherent in both test methods mean that they represent a severe case. Given these limitations, it is likely that the test methods, at their present stage of development, should be used as a means to qualitatively assess the relative effects on electrical Isolation of different contaminants.
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Static wheel/rail Contact Isolation due to track contamination
Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit, 2006Co-Authors: Roger Lewis, J MasingAbstract:Train detection can be by means of track circuits. Signaling block occupancy is triggered by the wheelset of the train `shorting out' the track circuit. Contaminants in the wheel/rail interface mean that Contact between the wheelsets and the track may be compromised, inhibiting train identification. This paper reports on an experimental study that was conducted to investigate the effect of contaminants such as sand and leaves on the electrical Isolation of a wheel/rail Contact. Tests were performed using sections cut from wheels and rail sections loaded together hydraulically with different combinations of contaminants in wet and dry conditions. The electrical circuit used was a simplified simulation of the TI21 track circuit. The sand results indicated that a transition exists in the amount of sand in the Contact above which Isolation occurred. This amount is higher than the specified sand application rate for train operation at 4.5 m/s (10 mile/h). At lower speeds, there is a possibility that this amount could enter the Contact if the applied sand rate is not reduced, leading to Isolation. Dead leaves presented the greatest problem in terms of Isolation. The addition of sand used to mitigate the problem of adhesion loss caused by leaf fall made the likelihood of Isolation greater. With water, breakdown loads were lower and partial conductance was seen to occur, although it is not clear whether these levels of conductance could be detected by a track circuit. Loads used represented an average value for the tread Contact. It was clear that for tests with dead leaves particularly, the breakdown loads were around this level. The problem could get worse with train masses gradually reducing, leading to lower wheel/rail Contact forces. The test method used here is shown to be suitable for qualitatively assessing relative effects of different contaminants on electrical Isolation. It can also be used to provide information for assessing where greater attention to leaf clearance is needed.
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Static wheel/rail Contact Isolation due to track contamination
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 2006Co-Authors: Roger Lewis, J MasingAbstract:An experimental study has been carried out to\r\ninvestigate the effect of sanding on the electrical\r\nIsolation of a wheel/rail Contact. Sand is applied to the\r\nwheel/rail interface to increase adhesion in both braking\r\nand traction. Train detection, for signalling purposes,\r\ncan be by means of track circuits. Signalling block\r\noccupancy is triggered by the wheelset of the train\r\n‘shorting out’ the track circuit. Sand in the wheel/rail\r\ninterface means that Contact between the wheelsets and\r\nthe track may be compromised, inhibiting train\r\nidentification.\r\n\r\nStatic tests were performed using sections cut\r\nfrom wheels and rail and dynamic tests on a twin disc\r\nmachine where rail and wheel steel discs are loaded\r\ntogether and driven under controlled conditions of\r\nrolling and slip. The electrical circuit used was a\r\nsimplified simulation of the TI21 track circuit.\r\n\r\nThe application of sand was carried out under a\r\nrange of mild and severe test conditions. The results\r\nindicated that a transition exists in the amount of sand\r\napplied, below which there is a measurable, but not\r\nsevere, change in voltage, but above which the Contact\r\nconductance decreases by an order of magnitude. A\r\nmodel of electrical Isolation has been developed\r\nassuming either full disc separation by a sand layer or\r\npartial disc Contact with some sand present.\r\n\r\nIdealisations inherent in both test methods mean\r\nthat they represent a severe case. Given these\r\nlimitations, it is likely that the test methods, at their\r\npresent stage of development, should be used as a\r\nmeans to qualitatively assess the relative effects on\r\nelectrical Isolation of different contaminants.
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Disc machine study of Contact Isolation during railway track sanding
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 2003Co-Authors: Roger Lewis, Rob Dwyer-joyce, J LewisAbstract:An experimental study has been carried out to investigate the effect of sanding on the electrical Isolation of a wheel/rail Contact. Sand is applied to the wheel/rail interface to increase adhesion in both braking and traction. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train 'shorting out' the track circuit. Sand in the wheel/rail interface means that Contact between the wheelsets and the track may be compromised, inhibiting train identification. Tests were performed on a twin-disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. Sand was fed into the disc Contact through a standard compressed air sanding valve. The electrical circuit used was a simplified simulation of the TI21 track circuit. The application of sand with and without water to the discs was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the sand flowrate below which there is a measurable, but not severe, change in voltage, but above which the Contact conductance decreases by an order of magnitude and the voltage tends towards its open-circuit value. The total Isolation time also showed a similar transition. Contact resistance was modelled assuming full disc separation by a sand layer and partial disc Contact with some sand present. Traction was monitored during the tests. A wet Contact showed approximately half the traction of a dry Contact. The addition of sand increased the traction to levels observed in a dry Contact. Idealizations inherent in the test method mean that it represents a severe case. The disc geometry is smaller than a wheel/rail Contact and both are in rotational motion. The sand nozzle was placed closer to the interface, leading to greater sand entrainment and low inductance. A fast data acquisition rate made the test circuit more sensitive to small fluctuations in Isolation than an actual track circuit. Given these limitations, it is likely that the test method, at its present stage of development, should be used as a means to assess qualitatively the relative effects on electrical Isolation of different contaminants.
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disc machine study of Contact Isolation during railway track sanding
Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit, 2003Co-Authors: Roger Lewis, R S Dwyerjoyce, J LewisAbstract:Sanding is often applied to the wheel/rail interface to increase adhesion in braking and traction. This study reports on an experimental study to investigate the effect of sanding on the electrical Isolation of a wheel/rail Contact. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train 'shorting out' the track circuit. Sand in the wheel/rail interface means that Contact between the wheelsets and the track may be compromised, inhibiting train identification. Tests were performed on a twin-disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. Sand was fed into the disc Contact through a standard compressed air sanding valve. A simplified simulation of the TI21 track electrical circuit was used. The application of sand with and without water to the discs was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the sand flowrate below which there is a measurable, but not severe, change in voltage, but above which the Contact conductance decreases by an order of magnitude and the voltage tends towards its open-circuit value. The total Isolation time also showed a similar transition. Contact resistance was modeled assuming full disc separation by a sand layer and partial disc Contact with some sand present. Traction was monitored during the tests. A wet Contact showed approximately half the traction of a dry Contact. The addition of sand increased the traction to levels observed in a dry Contact. Despite some limitations, the test method shows promise as a means to assess qualitatively the relative effects of different contaminants on electrical Isolation.
Emma S Mcbryde - One of the best experts on this subject based on the ideXlab platform.
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mathematical modelling of vancomycin resistant enterococci transmission during passive surveillance and active surveillance with Contact Isolation highlights the need to identify and address the source of acquisition
BMC Infectious Diseases, 2018Co-Authors: Agnes Loo Yee Cheah, Allen C Cheng, Denis Spelman, Roger L Nation, David C M Kong, Emma S McbrydeAbstract:Clinical studies and mathematical simulation suggest that active surveillance with Contact Isolation is associated with reduced vancomycin-resistant enterococci (VRE) prevalence compared to passive surveillance. Models using pre- and post-intervention data that account for the imperfect observation and serial dependence of VRE transmission events can better estimate the effectiveness of active surveillance and subsequent Contact Isolation; however, such analyses have not been performed. A mathematical model was fitted to surveillance data collected pre- and post-implementation of active surveillance with Contact Isolation in the haematology-oncology ward. We developed a Hidden Markov Model to describe undetected and observed VRE colonisation/infection status based on the detection activities in the ward. Bayesian inference was used to estimate transmission rates. The effectiveness of active surveillance was assumed to be via increased detection and subsequent Contact Isolation of VRE positive patients. We estimated that 31% (95% credible interval: 0.33–85%) of the VRE transmissions were due to cross-transmission between patients. The ratio of transmission rates from patients with Contact Isolation versus those without Contact Isolation was 0.33 (95% credible interval: 0.050–1.22). The majority of the VRE acquisitions in the haematology-oncology ward was estimated to be due to background rates of VRE, rather than within ward patient to patient acquisition. The credible interval for cross-transmission was wide which results in a large degree of uncertainty in the estimates. Factors that could account for background VRE acquisition include endogenous acquisition from antibiotic selection pressure and VRE in the environment. Contact Isolation was not significantly associated with reduced VRE transmission in settings where the majority of VRE acquisition was due to background acquisition, emphasising the need to identify and address the source of acquisition. As the credible interval for the ratio of VRE transmission in Contact isolated versus non-Contact isolated patients crossed 1, there is a probability that the transmission rate in Contact Isolation was not lower. Our finding highlights the need to optimise infection control measures other than active surveillance for VRE and subsequent Contact Isolation to reduce VRE transmission. Such measures could include antimicrobial stewardship, environmental cleaning, and hand hygiene.
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The role of general quality improvement measures in decreasing the burden of endemic MRSA in a medical-surgical intensive care unit.
Intensive Care Medicine, 2010Co-Authors: Michelle Ananda-rajah, Emma S Mcbryde, Kirsty L. Buising, Leanne Redl, Christopher Macisaac, John F. Cade, Caroline MarshallAbstract:Purpose To determine whether any of several quality improvement interventions with none specifically targeting methicillin-resistant Staphylococcus aureus (MRSA) were associated with a decline in endemic MRSA prevalence in an intensive care unit (ICU) where active screening and Contact Isolation precautions for known MRSA colonised patients are not practised.
Robert G. Sawyer - One of the best experts on this subject based on the ideXlab platform.
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Contact Isolation in surgical patients: a barrier to care?
Surgery, 2003Co-Authors: Heather L. Evans, Mary M. Shaffer, Michael G. Hughes, Robert L. Smith, Tae W. Chong, Daniel P. Raymond, Shawn J. Pelletier, Timothy L. Pruett, Robert G. SawyerAbstract:Background. Contact Isolation is commonly used to prevent transmission of resistant organisms. We hypothesized that Contact Isolation negatively impacts the amount of direct patient care. Methods. For 2 hours per day over a 5-week period, a single observer recorded provider/patient Contact in adjacent isolated and nonisolated patient rooms on both the surgical intensive care unit (ICU) and surgical wards of a university hospital. Number of visits, Contact time, and compliance with Isolation were recorded, as was illness severity as assessed by APACHE II score. Results. Isolated patients were visited fewer times than nonisolated patients (5.3 vs 10.9 visits/h, P
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Contact Isolation in surgical patients a barrier to care
Surgery, 2003Co-Authors: Heather L. Evans, Mary M. Shaffer, Michael G. Hughes, Robert L. Smith, Tae W. Chong, Daniel P. Raymond, Shawn J. Pelletier, Timothy L. Pruett, Robert G. SawyerAbstract:Background. Contact Isolation is commonly used to prevent transmission of resistant organisms. We hypothesized that Contact Isolation negatively impacts the amount of direct patient care. Methods. For 2 hours per day over a 5-week period, a single observer recorded provider/patient Contact in adjacent isolated and nonisolated patient rooms on both the surgical intensive care unit (ICU) and surgical wards of a university hospital. Number of visits, Contact time, and compliance with Isolation were recorded, as was illness severity as assessed by APACHE II score. Results. Isolated patients were visited fewer times than nonisolated patients (5.3 vs 10.9 visits/h, P <.0001) and had less Contact time overall (29 ± 5 vs 37 ± 3 min/h, P =.008), in the ICU (41 ± 10 vs 47 ± 5 min/h, P =.03), and on the floor (17 ± 3 vs 28 ± 4 min/h, P =.039), in spite of higher mean APACHE II scores in the isolated (10.1 ± 1.0 vs 7.6 ± 0.8, P =.05). Among floor patients with APACHE II scores greater than 10, patients in the isolated group had nearly 40% less Contact time per hour than patients in the nonisolated group (19 ± 4 vs 34 ± 7 min/h, P =.05). Conclusion. Because of the significantly lower Contact time observed, particularly among the most severely ill of floor patients, we propose a reexamination of the risk-benefit ratio of this infection control method. (Surgery 2003;134:180-8.)
J Lewis - One of the best experts on this subject based on the ideXlab platform.
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WHEEL/RAIL Contact Isolation DUE TO TRACK CONTAMINATION
2020Co-Authors: Roger Lewis, Rob Dwyer-joyce, J LewisAbstract:An experimental study has been carried out to investigate the effect of sanding on the electrical Isolation of a wheel/rail Contact. Sand is applied to the wheel/rail interface to increase adhesion in both braking and traction. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train ‘shorting out’ the track circuit. Sand in the wheel/rail interface means that Contact between the wheelsets and the track may be compromised, inhibiting train identification. Static tests were performed using sections cut from wheels and rail and dynamic tests on a twin disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. The electrical circuit used was a simplified simulation of the TI21 track circuit. The application of sand was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the amount of sand applied, below which there is a measurable, but not severe, change in voltage, but above which the Contact conductance decreases by an order of magnitude. A model of electrical Isolation has been developed assuming either full disc separation by a sand layer or partial disc Contact with some sand present. Idealisations inherent in both test methods mean that they represent a severe case. Given these limitations, it is likely that the test methods, at their present stage of development, should be used as a means to qualitatively assess the relative effects on electrical Isolation of different contaminants.
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Disc machine study of Contact Isolation during railway track sanding
Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 2003Co-Authors: Roger Lewis, Rob Dwyer-joyce, J LewisAbstract:An experimental study has been carried out to investigate the effect of sanding on the electrical Isolation of a wheel/rail Contact. Sand is applied to the wheel/rail interface to increase adhesion in both braking and traction. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train 'shorting out' the track circuit. Sand in the wheel/rail interface means that Contact between the wheelsets and the track may be compromised, inhibiting train identification. Tests were performed on a twin-disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. Sand was fed into the disc Contact through a standard compressed air sanding valve. The electrical circuit used was a simplified simulation of the TI21 track circuit. The application of sand with and without water to the discs was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the sand flowrate below which there is a measurable, but not severe, change in voltage, but above which the Contact conductance decreases by an order of magnitude and the voltage tends towards its open-circuit value. The total Isolation time also showed a similar transition. Contact resistance was modelled assuming full disc separation by a sand layer and partial disc Contact with some sand present. Traction was monitored during the tests. A wet Contact showed approximately half the traction of a dry Contact. The addition of sand increased the traction to levels observed in a dry Contact. Idealizations inherent in the test method mean that it represents a severe case. The disc geometry is smaller than a wheel/rail Contact and both are in rotational motion. The sand nozzle was placed closer to the interface, leading to greater sand entrainment and low inductance. A fast data acquisition rate made the test circuit more sensitive to small fluctuations in Isolation than an actual track circuit. Given these limitations, it is likely that the test method, at its present stage of development, should be used as a means to assess qualitatively the relative effects on electrical Isolation of different contaminants.
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disc machine study of Contact Isolation during railway track sanding
Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit, 2003Co-Authors: Roger Lewis, R S Dwyerjoyce, J LewisAbstract:Sanding is often applied to the wheel/rail interface to increase adhesion in braking and traction. This study reports on an experimental study to investigate the effect of sanding on the electrical Isolation of a wheel/rail Contact. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train 'shorting out' the track circuit. Sand in the wheel/rail interface means that Contact between the wheelsets and the track may be compromised, inhibiting train identification. Tests were performed on a twin-disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. Sand was fed into the disc Contact through a standard compressed air sanding valve. A simplified simulation of the TI21 track electrical circuit was used. The application of sand with and without water to the discs was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the sand flowrate below which there is a measurable, but not severe, change in voltage, but above which the Contact conductance decreases by an order of magnitude and the voltage tends towards its open-circuit value. The total Isolation time also showed a similar transition. Contact resistance was modeled assuming full disc separation by a sand layer and partial disc Contact with some sand present. Traction was monitored during the tests. A wet Contact showed approximately half the traction of a dry Contact. The addition of sand increased the traction to levels observed in a dry Contact. Despite some limitations, the test method shows promise as a means to assess qualitatively the relative effects of different contaminants on electrical Isolation.