Publications by authors named "Peter Tilley"

Objective: To evaluate the effectiveness of empiric antibiotic protocols for peripartum bacteremia at a quaternary institution by describing incidence, microbial epidemiology, clinical source of infection, susceptibility patterns, and maternal and neonatal outcomes.

Methods: Retrospective chart review of peripartum patients with positive blood cultures between 2010 and 2018.

Results: The incidence of peripartum bacteremia was 0.

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As part of the COVID-19 pandemic, clinical laboratories have been faced with massive increases in testing, resulting in sample collection systems, reagent, and staff shortages. We utilized self-collected saline gargle samples to optimize high throughput SARS-CoV-2 multiplex polymerase chain reaction (PCR) testing in order to minimize cost and technologist time. This was achieved through elimination of nucleic acid extraction and automation of sample handling on a widely available robotic liquid handler, Hamilton STARlet.

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Article Synopsis
  • Metagenomic techniques have revealed that various tissues previously thought to be sterile, including amniotic fluid, may actually harbor microorganisms, raising questions about the sterile womb hypothesis.
  • * The sterile womb hypothesis suggests that amniotic fluid must be free of microbes due to its role in protecting the fetus from maternal immune responses.
  • * The study introduces a new metagenomic method to detect microorganisms in small samples while minimizing contamination, confirming that mid-gestational amniotic fluid contains no detectable microorganisms, thus supporting the sterile womb hypothesis.
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The diagnostic sensitivity of observed and unobserved self-collected saline gargle samples for the molecular detection of SARS-CoV-2 in adults and school-aged children was evaluated against a reference standard of health care worker collected nasopharyngeal flocked swab. A total of 46 participants had a positive nasopharyngeal swab sample; of these, 10 were in the observed phase and 36 were in the unobserved phase. Only one matching saline gargle sample tested negative and this was in the unobserved phase, giving an overall sensitivity of 98%.

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To increase the repertoire of PCR based laboratory developed tests (LDTs) for the detection of SARS-CoV-2, we describe a new multiplex assay (SORP), targeting the SARS-CoV-2's, Spike and ORF8 genes. The widely used human RNaseP internal control was modified to specifically co-amplify the RNaseP mRNA. The SORP triplex assay was tested on a cohort (n = 372; POS = 144/NEG = 228) of nasopharyngeal flocked swab (NPFS) specimens, previously tested for the presence of SARS-CoV-2 using a PCR assay targeting E and RdRp genes.

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We assessed the performance, stability, and user acceptability of swab-independent self-collected saliva and saline mouth rinse/gargle sample types for the molecular detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in adults and school-aged children. Outpatients who had recently been diagnosed with COVID-19 or were presenting with suspected COVID-19 were asked to have a nasopharyngeal (NP) swab collected and provide at least one self-collected sample type. Participants were also asked about sample acceptability using a five-point Likert scale.

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Introduction: Early empiric treatment with broad-spectrum antimicrobials is common in neonatal intensive care units (NICU) due to the non-specific clinical presentation of infection. However, excessive and inappropriate antimicrobial use can lead to the emergence of drug-resistant organisms and adverse neonatal outcomes. This study aims to develop and implement a nationwide NICU-specific antimicrobial stewardship programme (ASP) to promote judicious antimicrobial use and control the emergence of multidrug-resistant organisms (MDROs) in Canada.

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The etiology of central nervous system (CNS) infections such as meningitis and encephalitis remains unknown in a large proportion of cases partly because the diversity of pathogens that may cause CNS infections greatly outnumber available test methods. We developed a metagenomic next generation sequencing (mNGS)-based approach for broad-range detection of pathogens associated with CNS infections suitable for application in the acute care hospital setting. The analytical sensitivity of mNGS performed on an Illumina MiSeq was assessed using simulated cerebrospinal fluid (CSF) specimens (n = 9).

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complex (Bcc) bacteria, currently consisting of 23 closely related species, and , can cause serious and difficult-to-treat infections in people with cystic fibrosis. Identifying bacteria to the species level is considered important for understanding epidemiology and infection control, and predicting clinical outcomes. Matrix-assisted laser desorption/ionization time-of-flight MS (MALDI-TOF) is a rapid method recently introduced in clinical laboratories for bacterial species-level identification.

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Background: The incidence of antibiotic-resistant urinary tract infections (UTIs) in children is increasing. The purpose of this study was to describe the incidence, clinical characteristics, and risk factors for third-generation cephalosporin-resistant UTIs presenting to the paediatric emergency department (ED).

Methods: This was a retrospective cohort study conducted at British Columbia Children's Hospital.

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Background: Kingella kingae has emerged as a significant cause of osteoarticular infections in young children. Pharyngeal colonization is considered a prerequisite for invasive K. kingae infection.

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Unlabelled: Clostridium difficile is the leading cause of healthcare-associated infections worldwide. The diagnosis of C. difficile infection (CDI) in pediatric oncology patients is complex as diarrhea is common, and there is a high rate of colonization in infants and young children.

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Commercial multiplex assays, built on different chemistries and platforms are widely available for simultaneous detection of pathogens that cause respiratory infections. However, these tests are often difficult to implement in a resource limited setting because of high cost. In this study, we developed and validated a method for simultaneous testing of common respiratory pathogens (Respanel) by real-time PCR in a convenient, strip-tube array format.

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Background: Our objective was to evaluate the appropriateness of antibiotic prescriptions in the neonatal intensive care unit using standardized criteria and determine the effects of an antimicrobial stewardship program (ASP) on patterns of antibiotic usage.

Methods: A retrospective audit of antibiotic use from July 2010 to June 2013 was conducted, focusing on prescriptions of vancomycin, cefotaxime, meropenem and linezolid for >3 calendar-days. We evaluated the appropriateness of each course of antibiotic treatment based on the Centers for Disease Control and Prevention 12-Step Guidelines to Prevent Antimicrobial Resistance (steps 4, 6 and 9).

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Pathogen immune responses are profoundly attenuated in fetuses and premature infants, yet the mechanisms underlying this developmental immaturity remain unclear. Here we show transcriptomic, metabolic and polysome profiling and find that monocytes isolated from infants born early in gestation display perturbations in PPAR-γ-regulated metabolic pathways, limited glycolytic capacity and reduced ribosomal activity. These metabolic changes are linked to a lack of translation of most cytokines and of MALT1 signalosome genes essential to respond to the neonatal pathogen Candida.

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Background: Polymerase chain reaction (PCR) testing of saliva swabs has been shown to be an attractive method to screen for congenital cytomegalovirus (CMV) infection. However, few data are available regarding the impact of pre-analytic methods on CMV DNA recovery from saliva samples under various conditions.

Objectives: The purpose of this study was to evaluate the impact of various transport media and transport conditions on the recovery of CMV DNA from spiked and clinical saliva samples from newborns using PCR testing.

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Article Synopsis
  • - Sodium bicarbonate is often mixed with lidocaine to make injections less painful, but in Canada, the vials are much larger than needed and are supposed to be single-use to avoid contamination.
  • - A study tested the growth of harmful bacteria in the sodium bicarbonate vials and found that while bacteria levels decreased after 7 days, they could still survive, raising concerns about potential transmission if vials are reused.
  • - The findings suggest that sodium bicarbonate should be treated as a single-use product, and to minimize waste, hospitals could consider using smaller vials or pre-mixing lidocaine with sodium bicarbonate.
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  • LAMP is a fast, cost-effective method for amplifying DNA/RNA, widely used in low-resource settings, but it struggles with false positives due to indirect detection methods.
  • A new method called FLOS-LAMP enhances accuracy by using a fluorescent probe that only lights up when it binds to the target DNA, significantly reducing false positives.
  • FLOS-LAMP has shown high sensitivity (96.8%) and specificity (100%) in detecting the Varicella-zoster virus, proving its effectiveness and versatility for various applications.
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Background. In the fall of 2014, a North American outbreak of enterovirus D68 resulted in a significant number of pediatric hospital admissions for respiratory illness throughout North America. This study characterized the clinical presentation and risk factors for a severe clinical course in children admitted to British Columbia Children's Hospital during the 2014 outbreak.

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We report a case of septic arthritis caused by a Bacillus species, B. pumilus, occurring in a healthy child. This organism rarely causes serious infections and has only been described in newborns and immunocompromised individuals or as a skin infection.

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Background.: Early definitive identification of infectious pathogens coupled with antimicrobial stewardship interventions allow for targeted and timely administration of antimicrobials. We investigated the combined impact of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) technology and an antimicrobial stewardship program (ASP) in pediatric patients with blood stream infections (BSIs).

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Background: Quantitative, viral load monitoring for BK virus (BKV) by real-time PCR is an important tool in the management of polyomavirus associated nephropathy in renal transplant patients. However, variability in PCR results has been reported because of polymorphisms in viral genes among different subtypes of BKV, and lack of standardization of the PCR assays among different laboratories. In this study we have compared the performance of several laboratory developed PCR assays that target highly conserved regions of BKV genome with a commercially available, RealStar(®) BKV PCR Kit.

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