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

Salmonella spp. are pathogenic microorganisms linked to foodborne outbreaks associated with eggs and egg products. Salmonella can resist sanitation of egg processing equipment and form biofilms on food-contact surfaces. A major challenge for controlling Salmonella 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 Salmonella 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 Salmonella began after three hours of incubation, with less than 1 log CFU/cm2 of growth. Silicone had the highest number of Salmonella attached (0.87 log CFU/cm2), followed by stainless steel (0.70 log CFU/cm2). Long-read whole genome sequencing identified attached Salmonella 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 Salmonella at low concentrations in the processing environment during the early stages of cell attachment to food-contact surfaces, allowing for correct sanitation intervention.