Rapid Detection of Salmonella Typhimurium During Cell Attachment on Three Food-Contact Surfaces Using Long-Read Sequencing

<i>Salmonella</i> spp. are pathogenic microorganisms linked to foodborne outbreaks associated with eggs and egg products. <i>Salmonella</i> can resist sanitation of egg processing equipment and form biofilms on food-contact surfaces. A major challenge for controlling <i>Salmonella</i> is the ability to detect the cells during the early stages of attachment to indicate that interventions are needed to sanitize the surface. This research investigated the use of long-read sequencing to identify <i>Salmonella</i> during the early stages (0-5 h) of cell attachment to three common food-contact surfaces-stainless steel, silicone, and nylon-and compared it with traditional microbiological methods. Results of the conventional plate counts showed that the detection of <i>Salmonella</i> began after three hours of incubation, with less than 1 log CFU/cm² of growth. Silicone had the highest number of <i>Salmonella</i> attached (0.87 log CFU/cm²), followed by stainless steel (0.70 log CFU/cm²). Long-read whole genome sequencing identified attached <i>Salmonella</i> on stainless steel, silicone, and nylon after only one hour of incubation. The results of this study suggest that long-read sequencing could be a very useful method for detecting <i>Salmonella</i> at low concentrations in the processing environment during the early stages of cell attachment to food-contact surfaces, allowing for correct sanitation intervention.