On-chip acoustophoretic isolation of microflora including S. typhimurium from raw chicken, beef and blood samples

Ngamsom, Bongkot; Lopez-Martinez, Maria J.; Raymond, Jean-Claude; Broyer, Patrick; Patel, Pradip; Pamme, Nicole

Abstract

Pathogen analysis in food samples routinely involves lengthy growth-based pre-enrichment and selective enrichment of food matrices to increase the ratio of pathogen to background flora. Similarly, for blood culture analysis, pathogens must be isolated and enriched from large excess of blood cells to allow further analysis. Conventional techniques of centrifugation and filtration are cumbersome, suffer from low sample throughput, are not readily amenable to automation and carry a risk of damaging biological samples. We report on-chip acoustophoresis as a pre-analytical technique for the resolution of total microbial flora from food and blood samples. The resulting ‘clarified’ sample is expected to increase the performance of downstream systems for the specific detection of the pathogens. A microfluidic chip with three inlets, a central separation channel and three outlets was utilized. Samples were introduced through the side inlets, buffer through the central inlet. Upon ultrasound actuation, large debris particles (10–100 μm) from meat samples were continuously partitioned into the central buffer channel, leaving the “clarified” outer sample streams containing both, the pathogenic cells and the background flora (ca. 1 μm) to be collected over a 30 min operation cycle before further analysis. The system was successfully tested with Salmonella typhimurium-spiked (ca. 103 CFU mL⁻¹) samples of chicken and minced beef, demonstrating a high level of the pathogen recovery (60–90%). When applied to S. typhimurium contaminated blood samples (107 CFU mL⁻¹), acoustophoresis resulted in a high depletion of the red blood cells (99.8%) which partitioned in the buffer stream, whilst sufficient numbers of the viable S. typhimurium remained in the outer channels for further analysis. These results indicate that the technology may provide a generic approach for pre-analytical sample preparation prior to integrated and automated downstream detection of bacterial pathogens.

Citation

Ngamsom, B., Lopez-Martinez, M. J., Raymond, J.-C., Broyer, P., Patel, P., & Pamme, N. (2016). On-chip acoustophoretic isolation of microflora including S. typhimurium from raw chicken, beef and blood samples. Journal of microbiological methods, 123, 79-86. https://doi.org/10.1016/j.mimet.2016.01.016

• Journal Article Type: Article
• Acceptance Date: Jan 29, 2016
• Online Publication Date: Feb 4, 2016
• Publication Date: Apr 1, 2016
• Deposit Date: Feb 5, 2016
• Publicly Available Date: Nov 23, 2017
• Journal: Journal of microbiological methods
• Print ISSN: 0167-7012
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 123
• Pages: 79-86
• DOI: https://doi.org/10.1016/j.mimet.2016.01.016
• Keywords: Acoustophoresis, Microbial flora resolution, Salmonella typhimurium, Sample preparation
• Public URL: https://hull-repository.worktribe.com/output/384965
• Publisher URL: http://www.sciencedirect.com/science/article/pii/S0167701216300161
• Additional Information: This article is maintained by: Elsevier; Article Title: On-chip acoustophoretic isolation of microflora including S. typhimurium from raw chicken, beef and blood samples; Journal Title: Journal of Microbiological Methods; CrossRef DOI link to publisher maintained version: http://dx.doi.org/10.1016/j.mimet.2016.01.016; Content Type: article; Copyright: Copyright © 2016 Elsevier B.V. All rights reserved.
• Contract Date: Nov 23, 2017