On-site magnetic screening tool for rapid detection of hospital bacterial infections: Clinical study with Klebsiella pneumoniae cells

Abstract

The high numbers of mortality related to drug-resistant bacterial superbugs have highlighted the need for rapid, highly sensitive, and cost-effective screening tools, ideally in seamless and point-of-need format. Herein, we report a portable in-flow magnetic transduction-based instrument capable of rapid and highly sensitive detection of whole-bacterial cells in complex matrices. Magnetoresistive (GMR) sensors are combined with microfluidic channels and interfaced with a low noise electronic architecture. The attained practical read-out allows for the interrogation of flowing samples containing small target biological entities (<5 μm). As a proof-of-concept, the device was first optimized for the detection of Klebsiella pneumoniae cells in laboratory samples, demonstrating a 100% sensitivity and 80.8% specificity. Further testing with clinical rectal swabs collected from 40 patients admitted to the hospital emergency department has unveiled its capability for bacteria detection in highly complex matrices with 100% sensitivity, without the need for a pre-enrichment step. Despite some false positives, a screening tool for such application greatly depends on its capacity to correctly identify all positive cases with proper isolation of suspected patients. The test provides a result after 20 min of exposure to 100 μL of sample volume. The magnetic device is a highly flexible tool, being easily customized to detect other bacterial species whenever a corresponding specific recognition ligand is available.

Keywords

• Magnetic sensors
• Nanoparticle detection
• Screening diagnostics
• Immunomagnetic labeling
• Fast Whole-bacterial cell identification
• Point-of-need