BIOE 500 Spring 2026 - Graduate Student Katie Koprowski

Gram Typing Bacteria Panels in Whole Blood Using a Biphasic Duplex-LAMP Assay

Abstract: Timely identification of bacteria in bloodstream infections is critical for guiding appropriate antibiotic treatment. However, current clinical workflows entail blood culture (1–5 days), followed by gram staining, PCR, and antibiotic susceptibility testing. These steps delay actionable results, often leading clinicians to prescribe broad-spectrum antibiotics without results from the above tests, contributing to the rising threat of antimicrobial resistance. Specifically, rapid information of even presence of gram-positive and/or gram-negative bacteria would help clinicians choose a specific antibiotic regiment after bacteriaemia is suspected. Here, we developed a rapid, culture-free method that identifies bacterial gram type from whole blood at a sensitivity of 1-5 CFU/L within 1.5 h. The assay features a duplex probe-based Detection of Amplification by Release of Quenching (DARQ) Loop-Mediated Isothermal Amplification (LAMP) system targeting seven of the most common bloodstream pathogens in blood cultures in published hospital reports. The two DARQ probes distinguish a panel of four of the most common gram-negative bacteria (E. coli, S. marcescens, P. mirabilis, K. pneumoniae) from three of the most common gram-positive bacteria (Methicillin-susceptible S. aureus, Methicillin-resistant S. aureus, S. epidermidis). Coupled with our “biphasic” sample preparation technique reported earlier (4 μL sample volume), the assay eliminates the need for blood culture, extraction & purification, provides gram type information, all the while achieving 1–5 CFU/μL sensitivity.

By Katie Koprowski, Department of Bioengineering, Faculty Advisor: Rashid Bashir