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Cooper B.S.,University of Oxford | Cooper B.S.,Mahidol University | Kypraios T.,University of Nottingham | Batra R.,King's College London | And 3 more authors.
PLoS Computational Biology | Year: 2012

An important determinant of a pathogen's success is the rate at which it is transmitted from infected to susceptible hosts. Although there are anecdotal reports that methicillin-resistant Staphylococcus aureus (MRSA) clones vary in their transmissibility in hospital settings, attempts to quantify such variation are lacking for common subtypes, as are methods for addressing this question using routinely-collected MRSA screening data in endemic settings. Here we present a method to quantify the time-varying transmissibility of different subtypes of common bacterial nosocomial pathogens using routine surveillance data. The method adapts approaches for estimating reproduction numbers based on the probabilistic reconstruction of epidemic trees, but uses relative hazards rather than serial intervals to assign probabilities to different sources for observed transmission events. The method is applied to data collected as part of a retrospective observational study of a concurrent MRSA outbreak in the United Kingdom with dominant endemic MRSA clones (ST22 and ST36) and an Asian ST239 MRSA strain (ST239-TW) in two linked adult intensive care units, and compared with an approach based on a fully parametric transmission model. The results provide support for the hypothesis that the clones responded differently to an infection control measure based on the use of topical antiseptics, which was more effective at reducing transmission of endemic clones. They also suggest that in one of the two ICUs patients colonized or infected with the ST239-TW MRSA clone had consistently higher risks of transmitting MRSA to patients free of MRSA. These findings represent some of the first quantitative evidence of enhanced transmissibility of a pandemic MRSA lineage, and highlight the potential value of tailoring hospital infection control measures to specific pathogen subtypes. © 2012 Cooper et al.


Iwashyna T.J.,Monash University | Iwashyna T.J.,University of Michigan | Iwashyna T.J.,Center for Clinical Management | Hodgson C.L.,Monash University | And 10 more authors.
Critical Care and Resuscitation | Year: 2015

We hypothesise that there exists a substantial and growing group of “persistently critically ill” patients who appear to be intensive care unit-dependent because of a cascade of critical illnesses rather than their original ICU admitting diagnosis. These persistently critically ill patients are those who remain in the ICU because of ongoing complications of care that continue after their reason for admission has been treated and is no longer active. We believe such patients can be distinguished from patients currently labelled as “chronic critical illness” or “prolonged mechanical ventilation”. We further believe that their primary problem is not simply failure to wean from mechanical ventilation due to muscle weakness and impaired gas exchange. We outline a program of clinician consultation, epidemiological research, consensus conference and validation to develop a useful definition of persistent critical illness, with the aim of supporting investigations in preventing persistence, and improving the care of patients so affected. © 2015, Critical Care and Resuscitation. All rights reserved.


Iwashyna T.J.,Monash University | Iwashyna T.J.,University of Michigan | Iwashyna T.J.,Center for Clinical Management Research | Hodgson C.L.,Monash University | And 7 more authors.
Critical Care and Resuscitation | Year: 2015

Objective: To identify the characteristics of patients with “persistent critical illness” (PerCI), as perceived by Australian and New Zealand intensive care unit clinicians. Patients with PerCI were defined as those whose reason for being in the ICU was now more related to their ongoing critical illness than their original reason for admission to the ICU. Design and participants: Using a web-based survey, we recruited clinicians affiliated with the Australian and New Zealand Intensive Care Society (ANZICS) Clinical Trials Group (CTG) who cared for adults. Clinicians included doctors, nurses, physiotherapists, dietitians, research managers and others. We used the ANZICS-CTG mailing list to email a single request for anonymous participation. Results: A total of 101 eligible clinicians responded to our survey. PerCI was believed to develop after a median of 10 days (IQR, 7–14 days), and to be somewhat uncommon (occurring in 10% of all ICU patients [IQR, 5%–15%], and in 50% of all patients with a prolonged ICU length of stay [IQR, 20%–60%]). Ninety per cent of respondents thought that patients with PerCI required ongoing invasive mechanical ventilation, and the most common problems were thought to be respiratory insufficiency (68%), delirium (59%) and acquired neuromuscular disease (54%). Ten per cent of patients with PerCI were expected to be alive and well and at home 6 months after ICU discharge, with another 15% alive and at home but requiring significant help. The remainder were expected to die within 6 months or to need institutional care. Conclusion: Patients with PerCI appear to be an identifiable group of ICU patients, with definable characteristics, substantial stress associated with their care, and poor perceived long-term outcomes. © 2015, Critical Care and Resuscitation. All rights reserved.


Delisle S.,Hopital du Sacre Coeur | Francoeur M.,Hopital du Sacre Coeur | Albert M.,Hopital du Sacre Coeur | Ouellet P.,The Intensive Care Unit | And 2 more authors.
Respiratory Care | Year: 2011

BACKGROUND: The available predictors of spontaneous-breathing-trial (SBT) success/failure lack accuracy. We devised a new index, the CORE index (compliance, oxygenation, respiration, and effort). OBJECTIVE: To compare the CORE index to the CROP index (compliance, rate, oxygenation, and pressure), airway-occlusion pressure 0.1 s after the start of inspiratory flow (P 0.1), and rapid shallow breathing index (RSBI) for predicting SBT success/failure in a critical care environment. METHODS: With 47 mechanically ventilated patients recovering from respiratory failure, of various causes, we prospectively examined the SBT success/failure prediction accuracy and calculated receiver operating characteristic curves, sensitivity, specificity, and likelihood ratios of CORE, CROP, P 0.1, and RSBI. RESULTS: The specificities were CORE 0.95, P 0.1 0.70, CROP 0.70, and RSBI 0.65. The sensitivities were CORE 1.00, CROP 1.00, P 0.1 0.93, and RSBI 0.89. The areas under the receiver operating characteristic curve were CORE 1.00 (95% CI 0.92-1.00), CROP 0.91 (95% CI 0.79-0.97), P 0.1 0.81 (95% CI 0.67- 0.91), and RSBI 0.77 (95% CI 0.62- 0.88). The positive likelihood ratios were CORE 20.0, CROP 3.3, P 0.1 3.1, and RSBI 2.5. The negative likelihood ratios were CORE 0.0, CROP 0.0, P 0.1 0.1, and RSBI 0.2. CONCLUSIONS: The CORE index was the most accurate predictor of SBT success/failure. © 2011 Daedalus Enterprises.

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