Publications by authors named "Kerstin Locher"

Whole genome sequencing (WGS), used as the main method for outbreak investigations, requires substantial technical expertise and is routinely done by reference laboratories. Therefore, the actionable information is often delayed. This study is the first to assess Fourier Transform Infrared (FTIR) spectroscopy as an alternative tool to investigate nosocomial Clostridioides difficile transmission.

View Article and Find Full Text PDF

Diagnosis of joint infections is often challenging due to low specimen volumes, low sensitivity of Gram stains and long incubation times of cultures. Digital PCR (dPCR) is a molecular tool that can detect nucleic acid targets with high sensitivity and resistance to inhibition. A 3 hour dPCR assay targeting the 16S gene was performed on archived synovial fluids.

View Article and Find Full Text PDF

This proof-of-concept study aimed to assess whether digital PCR (dPCR) technology could improve the detection of M. tuberculosis complex (MTB) from formalin-fixed paraffin-embedded (FFPE) tissue when compared to real-time PCR. A laboratory developed test using real-time PCR assay targeting the MTB-IS6110 was transitioned to dPCR technology.

View Article and Find Full Text PDF
Article Synopsis
  • False positive norovirus results were suspected after using the BioFire® FilmArray® Gastrointestinal panel at six labs in British Columbia, prompting further investigation.
  • The study involved additional molecular testing and whole genome sequencing (WGS) to confirm results from BF-GIP, with 215 out of 784 results initially suspecting false positives.
  • Ultimately, it was found that BF-GIP does produce false positives for norovirus, and these cannot be reliably predicted through a review of melting curves.
View Article and Find Full Text PDF

Background: Current molecular diagnostics are limited in the number and type of detectable pathogens. Metagenomic next-generation sequencing (mNGS) is an emerging, and increasingly feasible, pathogen-agnostic diagnostic approach. Translational barriers prohibit the widespread adoption of this technology in clinical laboratories.

View Article and Find Full Text PDF

Unlabelled: This study aimed to validate Metasystems' automated acid-fast bacilli (AFB) smear microscopy scanning and deep-learning-based image analysis module (Neon Metafer) with assistance on respiratory and pleural samples, compared to conventional manual fluorescence microscopy (MM). Analytical parameters were assessed first, followed by a retrospective validation study. In all, 320 archived auramine-O-stained slides selected non-consecutively [85 originally reported as AFB-smear-positive, 235 AFB-smear-negative slides; with an overall mycobacterial culture positivity rate of 24.

View Article and Find Full Text PDF

Background: Diagnosis of Clostridioides difficile Infection (CDI) entails compatible clinical presentation and laboratory findings. We evaluated real-time polymerase chain reaction (qPCR) cycle threshold (C) as a predictor for disease severity and TcdB enzyme immunoassay (EIA) results.

Methods: Inpatients or emergency department patients who tested positive for tcdB gene by PCR were evaluated.

View Article and Find Full Text PDF

Purpose: Vaginitis is caused by bacterial vaginosis (BV), Candida vaginitis (CV) and Trichomonas vaginalis (TV). This retrospective study evaluates the performance of the Aptima CV/TV, and BV assays on the automated Panther system.

Methods: Two hundred forty-two multitest swabs were tested on the CV/TV assay and 422 on the BV assay.

View Article and Find Full Text PDF

Two commercial real-time PCR assays for the detection of Pneumocystis jirovecii were compared, the quantitative RealStar P. jirovecii assay and the qualitative DiaSorin P. jirovecii assay, the latter of which can be used without nucleic acid extraction.

View Article and Find Full Text PDF

We compared the performance of ID NOW™ COVID-19 assay nasal swabs with RT-PCR of nasopharyngeal swabs for SARS-CoV-2 in an outbreak setting, determining whether addition of RT-PCR of residual nasal swabs (rNS) (post ID NOW™ elution) would increase overall analytic sensitivity. Devices were placed at 2 long term and 1 acute care sites and 51 participants were recruited. Prospective paired nasopharyngeal and nasal samples were collected for RT-PCR and ID NOW™.

View Article and Find Full Text PDF

Objectives: The COVID-19 pandemic and ensuing public health emergency has emphasized the need to study SARS-CoV-2 pathogenesis. The human microbiome has been shown to regulate the host immune system and may influence host susceptibility to viral infection, as well as disease severity. Several studies have assessed whether compositional alterations in the nasopharyngeal microbiota are associated with SARS-CoV-2 infection.

View Article and Find Full Text PDF

Sanger sequencing of the 16S rRNA gene is routinely used for the identification of bacterial isolates. However, this method is still performed mostly in more-specialized reference laboratories, and traditional protocols can be labor intensive. In this study, 99 clinical bacterial isolates were used to validate a fast, simplified, and largely automated protocol for 16S sequencing.

View Article and Find Full Text PDF

A large gap remains between sequencing a microbial community and characterizing all of the organisms inside of it. Here we develop a novel method to taxonomically bin metagenomic assemblies through alignment of contigs against a reference database. We show that this workflow, BugSplit, bins metagenome-assembled contigs to species with a 33% absolute improvement in F1-score when compared to alternative tools.

View Article and Find Full Text PDF

Objectives: The COVID-19 pandemic has underscored the need for rapid novel diagnostic strategies. Metagenomic Next-Generation Sequencing (mNGS) may allow for the detection of pathogens that can be missed in targeted assays. The goal of this study was to assess the performance of nanopore-based Sequence-Independent Single Primer Amplification (SISPA) for the detection and characterization of SARS-CoV-2.

View Article and Find Full Text PDF

The BioFire® COVID-19 Test and Respiratory Panel 2.1 (RP2.1) are rapid, fully automated assays for the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in nasopharyngeal swabs.

View Article and Find Full Text PDF

In light of the present pandemic of novel coronavirus disease 2019 (COVID-19) and the unprecedented high demand for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing worldwide, there are shortages of established specimen collection devices for respiratory viral testing for diagnostic microbiology laboratories. This creates the need to validate unverified collection devices from manufacturers that may not be a registered supplier for medical devices. As clinical laboratories do not routinely perform quality control of established collection devices, there is a need to have a systematic, robust approach to the assessment of substitute unregistered collection swabs and viral transport media (VTM).

View Article and Find Full Text PDF

The BioFire FilmArray Respiratory Panel (FA RP) is a rapid multiplexed molecular assay approved for detection of viral and atypical bacterial pathogens in nasopharyngeal specimens. This study aimed to evaluate the performance of the BioFire FilmArray Respiratory Panel v1.7 on bronchoscopy specimens.

View Article and Find Full Text PDF