Point-of-care diagnosis of invasive non-typhoidal Salmonella enterica in bloodstream infections using immunomagnetic capture and loop-mediated isothermal amplification

Abstract

Invasive non-typhoidal salmonellosis is gaining worldwide attention as an emerging disease cluster among bloodstream infections. The disease has the highest burden among immunocompromised and malnourished children in resource-limited areas due to poor access to reliable and rapid diagnostics. Point-of-care (POC) diagnostics are promising for use in such low infrastructure laboratory settings. However, there still remains a major challenge for POC testing to deal with the complexity of blood matrices in rapid detection of an extremely low concentration of blood-borne pathogens. In this work, the challenges were addressed by combining magnetic bead based pathogen concentration and Loop Mediated Isothermal Amplification (LAMP) technology. Sensitivity and performance of the combined approach were determined and compared with a direct PCR method. A direct visual detection strategy, adapted using SYTO-24 DNA intercalating dye, resulted in a limit of detection (LoD) as low as 14 CFU/mL in blood samples with a total analysis time of less than 2 h, including sample preparation. This approach has the potential for wide application as a high-throughput POC testing method to analyze pathogens in clinical, food, feed and environmental samples.

Keywords: Bloodstream infections; LAMP; Pathogens; Point of care; Rapid detection; Sample concentration.