Matrix properties strongly influence Salmonella survival and recoverability , which in turn affects the performance of any detection method. Key factors include water activity, pH, fat and protein content, solute load (e.g. salts and sugars), and intrinsic antimicrobials found in certain matrices such as herbs and spices. Physiological factors such as strain characteristics, growth phase and stress adaptation also play a role, while storage conditions (time, temperature, humidity) can further modify outcomes. As a result, strains that are readily detected in high-moisture matrices may be far more difficult to recover from low- moisture, high-fat or acidic foods . These biological and matrix-driven effects have direct methodological consequences, including differences in enrichment efficiency and colony development on differential or chromogenic agars , particularly when cells are stressed or injured. Matrix-relevant PT therefore provides a realistic appraisal of end-to-end workflow performance – from sample preparation and enrichment through confirmation and reporting. To ensure this assessment is meaningful, PT items should reflect the laboratory’s accredited scope under ISO/IEC 17025:2017 . For Salmonella detection, this means selecting PT samples that match routinely tested food matrices, ensuring performance is evaluated under conditions that reflect real-world analytical challenges. Matrix-relevant proficiency testing for Salmonella
Notable outbreaks:
2015 Cucumbers (Mexico), 907 cases, 6 deaths ( S. Poona )
2009 Peanut butter (USA), 714 cases, 9 deaths ( S. Typhimurium ); >3600 products recalled
2023 Cantaloupes (Mexico), 407 cases, 158 hospitalisations, 6 deaths ( S. Sundsval )
2013 Tahini (Turkey), 16 cases, 1 death ( S. Montevideo, S. Mbandaka )
3
lgcstandards.com/AXIO
Made with FlippingBook Online newsletter maker