MSACL 2026 Abstract

Bypassing Culture: Rapid Screening of Group A Streptococcal Pharyngitis

Linda Nartey(1), Victor Yuen(2), David Goodlett(1), Michael Chen(2)(3)
(1) University of Victoria, Victoria, BC, Canada (2) Vancouver Island Health Authority, Victoria, BC, Canada (3) University of British Columbia, Vancouver, BC, Canada

Michael Chen, MD MSc (Presenter) The University of British Columbia

Presenter Bio: Dr. Michael Chen is a clinical pathologist, specializing in clinical chemistry and translational mass spectrometry. He is the Department Head and Medical Director of Laboratory Medicine, Pathology and Medical Genetics at Island Health, and Provincial Discipline Lead at Provincial Health Services Authority. As a researcher, Dr Chen is the scientific director of UBC Translational Omics Lab in the Victoria General Hospital. He is also the director of Vancouver Island Biobank, and he co-chairs the BC Biobank Network. Dr. Chen’s research focuses on clinical mass spectrometry, biobanking, biomarker validation and clinical implementation.

Relevant Financial Disclosures (within past 24 months, reported on Apr 18, 2026) Ownership Interest Pataigin Inc Discussing Products? NO, presenter will NOT present educational content related to products/services of the ineligible company(ies) listed above. Conflict mitigation NOT REQUIRED.

INTRODUCTION:
Acute pharyngitis is one of the most frequent indications for primary care visits and antibiotic prescription, yet distinguishing Group A Streptococcus (GAS) from viral etiologies remains a critical diagnostic challenge. Current "gold standard" culture methods suffer from a 24–48 hour turnaround time, driving empiric prescribing and complicating antimicrobial stewardship. In the emergency department and inpatient settings, the diagnostic uncertainty leads to isolation delays, unnecessary admissions and inappropriate broad-spectrum antibiotics. Furthermore, rapid antigen tests often lack the sensitivity to rule out infection definitively. To address this gap, we propose the application of the lipidomics-based Fast Lipid Analysis Technique (FLAT) which is culture-independent. We previously published the application of FLAT in the diagnosis of urinary tract infections (UTIs) with > 95% sensitivity and specificity. Utilizing matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS) to detect membrane lipid signatures (cardiolipin) of S. pyogenes from throat swabs, FLAT reduces the timeline from days to 2 hours by performing the entire lipid extraction and chemical processing directly on the metal MALDI target plate.

METHODS:
We obtained throat swab media from 200 patients who needed GAS screening on Vancouver Island, Canada. We used the FLAT technique with lysozyme pretreatment to the peptidoglycan layer in the bacterial membrane prior to lipid extraction. The lipid extraction process was done on a MALDI plate. Briefly, 1 µL of media was spotted on a MALDI plate, acidified, incubated at 110 °C for 30 min, rinsed, and treated with norharmane matrix prior to analysis in negative linear ion mode on a Bruker Microflex. Results were compared to standard of care throat culture followed by protein-based identification using MALDI-TOF MS.

RESULTS:
In our preliminary study, FLAT showed a sensitivity and specificity of 90% and 85% respectively. The negative predictive value (NPV) was 90% suggesting the test is reliable for both ruling out infection within 2 hours. We conducted a process-based lifecycle assessment (LCA) comparing the conventional culture-based workflow and the culture independent FLAT workflow. Incorporating FLAT lipidomics-based screening into diagnostic workflows substantially reduces laboratory-associated greenhouse gas (GHG) emissions by 39% while preserving clinical diagnostic capacity.

CONCLUSION:
FLAT provides a rapid, robust, and environmentally friendly screening tool for GAS. By bypassing the culture bottleneck, this method allows for immediate clinical decision-making, significantly improving patient triage, appropriate isolation protocol and antibiotic utilization.