David Campbell Richardson

David Campbell Richardson
William Osler Health System

About

64
Publications
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1,826
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Publications

Publications (64)
Article
Full-text available
Background Older adults are at increased risk of mortality from influenza infections. We estimated influenza vaccine effectiveness (VE) against mortality following laboratory-confirmed influenza. Methods Using a test-negative design study and linked laboratory and health administrative databases in Ontario, Canada, we estimated VE against all-caus...
Article
IntroductionAnnual influenza vaccination is recommended for older adults, but evidence regarding the impact of repeated vaccination has been inconclusive.AimWe investigated vaccine effectiveness (VE) against laboratory-confirmed influenza and the impact of repeated vaccination over 10 previous seasons on current season VE among older adults.Methods...
Article
Background: Annual influenza immunization is recommended for people with chronic obstructive pulmonary disease (COPD) by all major COPD clinical practice guidelines. We sought to determine the seasonal influenza vaccine effectiveness (VE) against laboratory-confirmed influenza-associated hospitalizations among older adults with COPD. Methods: We...
Article
Full-text available
Background: Recent studies have demonstrated the possibility of negative associations between prior influenza vaccines and subsequent influenza vaccine effectiveness (VE), depending on season and strain. We investigated this association over 4 consecutive influenza seasons (2011-2012 through 2014-2015) in Canada. Methods: Using a matched test-ne...
Article
Purpose: Seasonal influenza vaccination is recommended for patients with cancer despite concerns of disease or treatment-associated immunosuppression. The objective of this study was to evaluate vaccine effectiveness (VE) against laboratory-confirmed influenza for patients with cancer. Patients and methods: We conducted an observational test-neg...
Article
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Background: The Serious Outcomes Surveillance Network of the Canadian Immunization Research Network (CIRN SOS) has been performing active influenza surveillance since 2009 (ClinicalTrials.gov identifier: NCT01517191). Influenza A and B viruses are identified and characterized using real-time reverse-transcriptase polymerase chain reaction (RT-PCR)...
Article
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Background Linking data on laboratory specimens collected during clinical practice with health administrative data permits highly powered vaccine effectiveness (VE) studies to be conducted at relatively low cost, but bias from using convenience samples is a concern. We evaluated the validity of using such data for estimating VE. Methods We created...
Article
Background: The effectiveness of influenza vaccination in reducing influenza-related hospitalizations among patients with COPD is not well described, and influenza vaccination uptake remains suboptimal. Methods: Data were analyzed from a national, prospective, multicenter cohort study including patients with COPD, hospitalized with any acute res...
Article
Background: Carbapenemase-producing Enterobacteriaceae (CPE) infections are a rapidly evolving global threat. With bacteremia mortality rates exceeding 40%, limited consensus exists regarding optimal antimicrobial treatment. Objectives: To characterize our institution’s CPE bacteremia population and describe the antimicrobial regimens used for trea...
Article
Background: Respiratory illnesses are a major contributor to pediatric hospitalizations, with influenza and respiratory syncytial virus (RSV) causing substantial morbidity and cost each season. We compared the characteristics and outcomes of children 0-59 months of age who were hospitalized with laboratory-confirmed influenza or RSV between 2009 a...
Article
Background: Ongoing assessment of influenza vaccine effectiveness (VE) is critical to inform public health policy. This study aimed to determine the VE of trivalent influenza vaccine (TIV) for preventing influenza-related hospitalizations and other serious outcomes over three consecutive influenza seasons. Methods: The Serious Outcomes Surveilla...
Article
Background: Acute myocardial infarction can be triggered by acute respiratory infections. Previous studies have suggested an association between influenza and acute myocardial infarction, but those studies used nonspecific measures of influenza infection or study designs that were susceptible to bias. We evaluated the association between laborator...
Article
Full-text available
Background: The Serious Outcomes Surveillance (SOS) Network was established to monitor seasonal influenza complications among hospitalized Canadian adults and to assess the effectiveness of influenza vaccination against severe outcomes. Here we report age- and strain-specific vaccine effectiveness (VE) in preventing severe outcomes during a season...
Article
Full-text available
Uncertainty remains regarding the magnitude of effectiveness of influenza vaccines for preventing serious outcomes, especially among young children. We estimated vaccine effectiveness (VE) against laboratory-confirmed influenza hospitalizations among children aged 6–59 months. We used the test-negative design in hospitalized children in Ontario, Ca...
Data
Additional descriptive characteristics of fully vaccinated, partially vaccinated and unvaccinated hospitalized children. (DOCX)
Data
Influenza circulation periods, recommended vaccine strains, and dominant circulating subtypes, by season. (DOCX)
Data
Classification of complex chronic conditions derived from Feudtner’s and applied to CIHI-DAD at ICES, including codes applied to ICD-10-CA. (DOCX)
Data
List of included ICD-10-CA codes to define ARI hospitalizations. (DOCX)
Data
Additional descriptive characteristics of influenza test-positive and influenza test-negative hospitalized children. (DOCX)
Data
Unadjusted vaccine effectiveness estimates. (DOCX)
Data
Impact of misclassification of vaccination status on VE estimates, by a) changing sensitivity and b) changing specificity. (DOCX)
Article
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Background: Consideration of cost determinants is crucial to inform delivery of public vaccination programs. Objectives: To estimate the average total cost of laboratory-confirmed influenza requiring hospitalization in Canadians prior to, during, and 30 days following discharge. To analyze effects of patient/disease characteristics, treatment, a...
Article
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Background Recent controversy has arisen from observational studies suggesting a potential negative association between prior influenza vaccination and subsequent influenza vaccine effectiveness (VE). As immunologic theories suggest this impact could vary by season/strain, we investigated this association over 4 influenza seasons in Canada. Method...
Article
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Background Antiviral treatment of influenza in outpatient settings is associated with modest improvement in outcomes but benefit in inpatient settings remains unclear. We assessed the impact of antiviral treatment on the severe outcomes death and intensive care unit (ICU) admission and/or need for mechanical ventilation (MV) in hospitalized influen...
Article
Full-text available
Background Influenza virus activity varies seasonally and within season. Epidemiology of serious influenza outcomes is contingent on the prevalent circulating strain/s and susceptible age group/s. Given the strain variability over the 2011–2012 through 2013–2014 seasons in Canada, this study examined the clinical and epidemiological profiles of dif...
Article
Full-text available
Background Influenza vaccination programs aim to prevent serious outcomes. Given that frailty may impact recovery from influenza, we examined frailty as a predictor of recovery in older adults hospitalized with acute respiratory illness. Methods Data came from the Canadian Immunization Research Network (CIRN) Serious Outcomes Surveillance (SOS) Ne...
Article
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Background CPE are a growing threat worldwide. Screening to identify colonization is critical to control transmission in hospitals, but the sensitivity of screening of different anatomic sites to detect colonization remains uncertain. We describe the results of CPE screening by anatomic site in a study of duration of colonization in Toronto, Canada...
Article
Background: Influenza is an important cause of morbidity and mortality among older adults. Even so, effectiveness of influenza vaccine for older adults has been reported to be lower than for younger adults, and the impact of frailty on vaccine effectiveness (VE) and outcomes is uncertain. We aimed to study VE against influenza hospitalization in o...
Article
Background: Data on factors associated with the use of antiviral medication to treat influenza in both children and adults are limited. Objectives: To describe trends in antiviral use, analyze factors associated with antiviral treatment of hospitalized patients with influenza, and to compare use based on guidelines. Study design: A retrospecti...
Article
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Here, we present the draft genome sequences of two strains (K068 and C860) of the genospecies “ Haemophilus quentini .” The isolates were recovered from blood cultures of a newborn neonate and an elderly patient with septicemia in Ontario, Canada.
Article
OBJECTIVE To measure transmission frequencies and risk factors for household acquisition of community-associated and healthcare-associated (HA-) methicillin-resistant Staphylococcus aureus (MRSA). DESIGN Prospective cohort study from October 4, 2008, through December 3, 2012. SETTING Seven acute care hospitals in or near Toronto, Canada. PARTICI...
Article
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A male patient was admitted in a community hospital in Ontario, Canada, with an infected sacral ulcer after returning from India, where he was hospitalized. Carbapenem resistant Escherichia coli (isolated from blood cultures), Enterobacter cloacae and Providencia stuartii (from urine samples) were recovered, all positive for blaNDM-1. Comparative N...
Conference Paper
Background: Diagnosis of influenza in the elderly may be complicated by atypical presentations. We compared the characteristics of community-dwelling adults aged ≥60 years presenting to EDs during the 2011/12 and 2012/13 influenza seasons. Methods: We identified patients presenting to six EDs with influenza-compatible symptoms. Clinical character...
Article
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During the 2013/14 influenza season in Canada, 631 of 654 hospitalisations for laboratory-confirmed influenza enrolled in sentinel hospitals were due to Influenza A. Of the 375 with known subtype, influenza A(H1N1) accounted for 357. Interim unmatched vaccine effectiveness adjusted for age and presence of one or more medical comorbidities was deter...
Article
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Methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infections (BSI) are associated with considerable morbidity and mortality, especially with persistent (PB) or recurrent bacteremia (RB). OBJECTIVE: To determine the frequency of PB and RB in patients with MRSA BSI, and to characterize the isolates from these patients. METHODS: Surveill...
Article
In 1995, a publicly funded pneumococcal vaccination program for 23-valent polysaccharide vaccine (PPV23) was introduced in Ontario. Conjugate vaccines were authorized in 2001 (PCV7), 2009 (PCV10) and 2010 (PCV13). From 1995-2011, active, population-based surveillance for invasive pneumococcal disease (IPD) was conducted in Metropolitan Toronto and...
Conference Paper
Background: Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) is distinct from healthcare-associated MRSA (HA-MRSA) in its epidemiology and microbiologic characteristics. This study describes MRSA transmission and body site colonization patterns within households (HH) of known colonized/infected individuals. Methods: Inde...
Article
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Background: New Delhi metallo-ß-lactamase (NDM) has emerged worldwide in clinically relevant gram-negative bacteria. We report an outbreak of NDM-producing Klebsiella pneumoniae in patients with no prior travel history to endemic regions. Methods: Five NDM-1-producing K. pneumoniae colonizing and/or clinically infecting patients in a community t...
Article
After recent hospitalization in India (New Delhi and Mumbai), 2 patients, on their return to Canada, presented with lower urinary tract infections due to multiresistant Klebsiella pneumoniae that produced New Delhi metallo-β-lactamase and CTX-M-15. The organisms belonged to clones ST147 and ST340, and were positive for aac(6')-Ib-cr, as well as for...
Article
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Neuraminidase inhibitors (NAIs), oseltamivir and zanamivir have played an essential role in the prophylaxis and treatment of influenza.…
Article
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To the Editor: The New Delhi metallo-beta-lactamase (NDM-1) was first characterized in 2009 from Klebsiella pneumoniae and Escherichia coli isolated from a patient in Sweden who had received medical care in New Delhi, India (1). Further studies have shown broad dissemination of this beta-lactamase gene (blaNDM-1) in India, Pakistan, Bangladesh, and...
Article
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Phenotypic and genotypic methods were used to characterize extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli isolated in 2007 from 11 different Canadian medical centers. Of the 209 ESBL-producing E. coli isolates tested, 148 (71%) produced CTX-M-15, 17 (8%) produced CTX-M-14, 5 (2%) produced CTX-M-3, and 1 produced CTX-M-27. Overall,...
Conference Paper
Background: Invasive MRSA infections cause significant mortality. VA is used for treatment; however, Rx failure may occur in susceptible (susc) isolates due to hVISA or tolerance (TO). The prevalence of reduced susc or TO to VA was determined. Methods: Consecutive invasive MRSA were evaluated. Susc. methods included broth microdilution (BMD) GPN3F...
Article
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We compared the results of Gram staining and culture of cerebrospinal fluid to results obtained with a rapid PCR assay for the diagnosis of meningococcal meningitis in 281 cases of suspected bacterial meningitis. PCR had a sensitivity of 97% compared to a sensitivity of 55% for culture, and the PCR specificity was 99.6%. PCR results were available...
Article
With the advent of molecular diagnostics culture-negative endocarditis caused by the organism Tropheryma whippelii is an increasingly described entity. We describe two patients with afebrile, culture-negative endocarditis caused by T. whippelii who had neither the gastrointestinal nor arthritic manifestations of Whipple's disease. Whipple's disease...
Article
Full-text available
Microscopy has been the traditional reference standard for malaria diagnosis. However, difficulty in maintaining the required technical skills, particularly in areas where malaria is not endemic, has prompted the development of rapid nonmicroscopic diagnostic assays based on the detection of malaria parasite antigen in whole blood. In this study, w...
Article
Full-text available
To determine if susceptibility testing of Streptococcus pneumoniae could detect those isolates that had one of the recognized mechanisms of fluoroquinolone resistance, 101 isolates were selected; the levofloxacin MIC for 28 of these isolates was ≥4 μg/ml. Only isolates with both parC andgyrA mutations or with no recognized resistance mechanisms wer...
Article
A 45-year-old man underwent renal transplant for end-stage renal disease complicating systemic lupus erythematosis. Within 24 hours of initiating Pneumocystis carinii pneumonia (PCP) prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) he developed fever and confusion. Cerebrospinal fluid examination revealed a pleocytosis but cultures were neg...
Article
The purpose of this study was to investigate the relationship between aspects of the feminine gender role and modes of illness behavior in patients with irritable bowel syndrome (IBS). Fifty IBS patients (34 women and 16 men) completed the Personal Attributes Questionnaire (PAQ), which assesses aspects of gender role, and the Illness Behavior Quest...
Article
Intrinsic electrical activities in various isolated segments of the mouse small intestine were recorded (i) to characterize action potential generation and (ii) to obtain a profile on the ion channels involved in initiating the slow wave type action potentials (slow waves). Gradients in slow wave frequency, resting membrane potential, and occurrenc...
Article
From 1988 to 1992, 4,182 coronary bypass grafting procedures were performed at the University of Ottawa Heart Institute. The left internal thoracic artery (ITA) was used in 2,913 patients, the right ITA in 79, and bilateral ITAs in 61 for a total of 3,053 patients with ITAs. This study assessed patients requiring angioplasty for symptomatic ITA ste...
Article
Actions of activators of glibenclamide sensitive K+ channels on canine colonic circular muscle were investigated. Cromakalim as well as its (-) enantiomer lemakalim caused inhibition of spontaneous phasic contractile activity (EC50's 4.4 +/- 0.1 x 10(-7) M and 2.3 +/- 0.4 x 10(-7) M, respectively) and of carbachol induced activity (EC50's: 9.4 +/-...

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