Publications by authors named "Derek MacFadden"

Background: Antimicrobial-resistant (AMR) pathogens represent an ongoing global health burden. Colonization is often a prerequisite for infection, but the risk of infection after AMR colonization is not well understood. Using population-level health administrative data, we sought to investigate the risk of infection with the same AMR organism after detection of colonization.

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Background: To investigate the prevalence of concomitant bacterial infection across common viral infections.

Methods: This population-based cohort study included patients infected with influenza A and B (FLUA, FLUB) and respiratory syncytial virus (RSV) in Ontario between 2017 and 2019 and patients with SARS-CoV-2 between 2020 and 2021. Specific bacteria present in concomitant infections were identified.

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Unlabelled: Timely diagnostic tools are needed to improve antibiotic treatment. Pairing metagenomic sequencing with genomic neighbor typing algorithms may support rapid clinically actionable results. We created resistance-associated sequence elements (RASE) databases for and .

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Background: Bloodstream infections are associated with substantial morbidity and mortality. Early, appropriate antibiotic therapy is important, but the duration of treatment is uncertain.

Methods: In a multicenter, noninferiority trial, we randomly assigned hospitalized patients (including patients in the intensive care unit [ICU]) who had bloodstream infection to receive antibiotic treatment for 7 days or 14 days.

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Objectives: Although surgical site infection (SSI) is a commonly used quality metric after lower-limb revascularization surgery, outcomes associated with development of this complication are poorly characterized. We conducted a systematic review and meta-analysis of studies reporting associations between development of an SSI after these procedures and clinical outcomes and healthcare resource use.

Methods: We searched MEDLINE, Embase, CENTRAL, and Evidence-Based Medicine Reviews (inception to April 4th, 2023) for studies examining adjusted associations between development of an SSI after lower-limb revascularization surgery and clinical outcomes and healthcare resource use.

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Background: Recent work demonstrated that detection of SARS-CoV-2 on the floor of long-term care facilities is associated with impending COVID-19 outbreaks. It is unknown if similar results will be observed in hospitals.

Methods: Floor swabs were prospectively collected weekly from healthcare worker-only areas (eg, staff locker rooms) at two hospitals in Ontario, Canada for 39 weeks.

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Article Synopsis
  • The study analyzed the risk factors and outcomes for patients with Gram-negative bloodstream infections (GN-BSI) who experience persistent bacteraemia, which is when bacteria remain in the bloodstream after initial treatment.
  • Out of 8807 hospitalized patients, 600 (6.8%) exhibited persistent bacteraemia, linked to factors like having a permanent catheter, antimicrobial resistance, ICU admission, and specific types of infections.
  • The research found that patients with persistent bacteraemia had significantly higher mortality rates within 30 days (17.2%) and 90 days (25.5%) compared to those without, suggesting the need for better risk assessment tools for these patients.
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Article Synopsis
  • The study aimed to validate a simple EMR-based SEPSIS score designed to predict sepsis outcomes in a large cohort of patients across multiple hospitals in Toronto, addressing the limitations of existing scores.
  • It involved a retrospective analysis of patients admitted with sepsis over two time periods, assessing in-hospital mortality, ICU admission, and length of stay, with the SEPSIS score incorporating four lab-based predictors.
  • The findings revealed that the SEPSIS score had comparable effectiveness to established scoring systems (qSOFA and NEWS2) in predicting mortality and other significant clinical outcomes, suggesting its utility in clinical settings.
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Background: It is unclear whether antibiotics impact delirium outcomes in older adults with pyuria or bacteriuria in the absence of systemic signs of infection or genitourinary symptoms.

Methods: We registered our systematic review protocol with PROSPERO (CRD42023418091). We searched the Medline and Embase databases from inception until April 2023 for studies investigating the impact of antimicrobial treatment on the duration and severity of delirium in older adults (≥60 years) with pyuria (white blood cells detected on urinalysis or dipstick) or bacteriuria (bacteria growing on urine culture) and without systemic signs of infection (temperature > 37.

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Background: The rapid global emergence of the COVID-19 pandemic in early 2020 created urgent demand for leading indicators to track the spread of the virus and assess the consequences of public health measures designed to limit transmission. Public transit mobility, which has been shown to be responsive to previous societal disruptions such as disease outbreaks and terrorist attacks, emerged as an early candidate.

Methods: We conducted a longitudinal ecological study of the association between public transit mobility reductions and COVID-19 transmission using publicly available data from a public transit app in 40 global cities from March 16 to April 12, 2020.

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Background: The use of adjunctive antibiotics directed against exotoxin production in Staphylococcus aureus bacteremia (SAB) is widespread, and it is recommended in many guidelines, but this is based on limited evidence. Existing guidelines are based on the theoretical premise of toxin suppression, as many strains of S. aureus produce toxins such as leukocidins (eg, Panton-Valentine leukocidin, toxic shock syndrome toxin 1, exfoliative toxins, and various enterotoxins).

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Objectives: Data supporting routine infectious diseases (ID) consultation in gram-negative bloodstream infection (GN-BSI) are limited. We evaluated the association between ID consultation and mortality in patients with GN-BSI in a retrospective population-wide cohort study in Ontario using linked health administrative databases.

Methods: Hospitalized adult patients with GN-BSI between April 2017 and December 2021 were included.

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Article Synopsis
  • Floor swabs from six elementary schools in Ottawa were tested for the SARS-CoV-2 virus.
  • The results indicated no link between test positivity and student grade levels, absenteeism, pediatric hospitalizations, or community wastewater levels.
  • Interestingly, schools in areas with a history of higher COVID-19 rates had fewer positive swabs, but this result was not statistically significant.
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Background: Coronavirus disease 2019 (COVID-19) vaccination has been associated with reduced outpatient antibiotic prescribing among older adults with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We assessed the impact of COVID-19 vaccination on outpatient antibiotic prescribing in the broader population of older adults, regardless of SARS-CoV-2 infection status.

Methods: We included adults aged ≥65 years who received their first, second, and/or third COVID-19 vaccine dose from December 2020 to December 2022.

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Article Synopsis
  • A study investigated the effectiveness of follow-up blood cultures (FUBCs) on mortality rates in patients with Gram-negative bloodstream infections (GN-BSI) in Ontario, Canada, determining that their utility is controversial due to previous observational studies' limitations.
  • The analysis included over 34,000 hospitalized adults, revealing that 25.8% received FUBCs, with no significant difference in 30-day mortality rates between those who did and those who did not (10.1% vs. 8.9%).
  • Results also indicated that patients receiving FUBCs had longer hospital stays (11 days vs. 7 days) and fewer days alive outside the hospital, suggesting that while FUBCs
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Background: Self-reported penicillin allergy labels are common and often inaccurate after assessment. These labels can lead to reduced use of first-line beta-lactam antibiotics and worse outcomes. We measured the impact of a previously performed inpatient proactive systematic penicillin allergy de-labelling program on subsequent antibiotic use.

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Tools to advance antimicrobial stewardship in the primary health care setting, where most antimicrobials are prescribed, are urgently needed. The aim of this study was to evaluate OPEN Stewarship (Online Platform for Expanding aNtibiotic Stewardship), an automated feedback intervention, among a cohort of primary care physicians. We performed a controlled, interrupted time-series study of 32 intervention and 725 control participants, consisting of primary care physicians from Ontario, Canada and Southern Israel, from October 2020 to December 2021.

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An interrupted time-series study design was implemented to evaluate the impact of antibiotic stewardship interventions on antibiotic prescribing among veterinarians. A total of 41 veterinarians were enrolled in Canada and Israel and their prescribing data between 2019 and 2021 were obtained. As an intervention, veterinarians periodically received three feedback reports comprising feedback on the participants' antibiotic prescribing and prescribing guidelines.

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Decision Support Tools for Antibiotic PrescribingChoosing the right antibiotic is challenging. Unnecessarily broad-spectrum antibiotic treatment promotes antimicrobial resistance; inappropriately narrow-spectrum antibiotic use can lead to treatment failure. A cluster-randomized trial of a model-informed clinical decision support tool is proposed for guiding empiric antibiotic therapy for hospitalized patients with suspected infection.

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Article Synopsis
  • * Over 14 months, they collected nearly 5,000 swabs, finding a significant correlation between positive floor swabs and the identification of Covid-19 outbreaks, especially during outbreak periods.
  • * The results indicate that floor sampling could be a valuable tool for early detection of Covid-19 outbreaks, with many positive swabs occurring days before the official outbreak identification.
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Objectives: International Classification of Diseases (ICD) codes are commonly used to identify cases of diabetic ketoacidosis (DKA) in health services research, but they have not been validated. Our aim in this study was to assess the accuracy of ICD, 10th revision (ICD-10) diagnosis codes for DKA.

Methods: We conducted a multicentre, cross-sectional study using data from 5 hospitals in Ontario, Canada.

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Background: Resource utilization and costs can impede proactive assessment and de-labeling of penicillin allergy among inpatients.

Methods: Our pilot intervention was a proactive penicillin allergy de-labeling program for new inpatients with penicillin allergy. Patients deemed appropriate for a challenge with a low-risk penicillin allergy history were administered 250 mg amoxicillin and monitored for 1 h.

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Background: Empiric antibiotic treatment selection should provide adequate coverage for potential pathogens while minimizing unnecessary broad-spectrum antibiotic use. We sought to pilot a sepsis treatment algorithm to individualize antibiotic recommendations, and thereby improve early antibiotic de-escalation while maintaining adequacy of coverage (Early-IDEAS).

Methods: In this observational study, the Early-IDEAS decision support algorithm was derived from previous Gram- negative and Gram-positive prediction rules and models along with local guidelines, and then applied to prospectively identified consecutive adults within 24 hours of suspected sepsis.

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Bacterial infections are a significant cause of morbidity and mortality worldwide. In the wake of the COVID-19 pandemic, previous studies have demonstrated pandemic-related shifts in the epidemiology of bacterial bloodstream infections (BSIs) in the general population and in specific hospital systems. Our study uses a large, comprehensive data set stratified by setting [community, long-term care (LTC), and hospital] to uniquely demonstrate how the effect of the COVID-19 pandemic on BSIs and testing practices varies by healthcare setting.

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