Cantaloupe facilitates transmission of Salmonella typhimurium between adult house flies

Authors: THOMSON, JESSICA - Kansas State University; Yeater, Kathleen; ZUREK, LUDEK - Kansas State University; Nayduch, Dana

Submitted to: Entomological Society of America Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/8/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Salmonella enterica ser. Typhimurium (S. Typhimurium) is a pathogen harbored by livestock that can contaminate fresh produce, such as cantaloupe, and cause food-borne illnesses. We previously demonstrated that house flies acquire and harbor S. Typhimurium after exposure to cattle manure containing this pathogen. Fly to fly, fly to food, food to fly and fly to food to fly transmission of this pathogen has not been investigated. Because house flies are attracted to human food, we investigated the transmission of S. Typhimurium from Salmonella-inoculated flies to cantaloupe, from inoculated cantaloupe to flies, and between inoculated and control flies in the presence and absence of cantaloupe. Mated female house flies were exposed to manure inoculated with sterile PBS (CF) or S. Typhimurium (SF) for 12 h. We predicted that S. Typhimurium would be transferred from inoculated food to control flies (CF), from inoculated flies (SF) to food, and from fly-food-fly (SF-food-CF) and that transmission success would increase with exposure/contact time. To test transmission of S. Typhimurium, flies were placed in jars containing either: 1) a single SF with fresh cantaloupe (fly-food transmission); 2) four CF with S. Typhimurium-inoculated cantaloupe (food-fly transmission); or 3) a single SF with four CF with and without fresh cantaloupe (fly-fly transmission, with and without food). Our experiments demonstrated that S. Typhimurium multiplied on cantaloupe, was transferred to and acquired from cantaloupe by flies, and that the presence of cantaloupe facilitated fly to fly transmission. Understanding bacterial transmission between flies and food can help in assessing the role flies play in health and food safety for this pathogen.

Technical Abstract: Salmonella enterica ser. Typhimurium (S. Typhimurium) is a pathogen harbored by livestock that can contaminate fresh produce, such as cantaloupe, and cause food-borne illnesses. We previously demonstrated that house flies acquire and harbor S. Typhimurium after exposure to inoculated cattle manure. However, fly to fly transmission of bacteria has not been demonstrated. Because house flies are attracted to human food, we investigated the transmission of S. Typhimurium from inoculated flies to cantaloupe, from inoculated cantaloupe to flies, and between inoculated and control flies in the presence and absence of cantaloupe. We hypothesized that S. Typhimurium is transferred from inoculated food to control flies (CF), from inoculated flies (SF) to food, and from fly-food-fly (SF-food-CF) and that transmission success would increase with exposure time. Mated female house flies were exposed to manure inoculated with sterile PBS (CF) or S. Typhimurium (SF) for 12 h. To test transmission of S. Typhimurium, flies were placed in jars containing either: 1) a single SF with fresh cantaloupe (fly-food transmission); 2) four CF with S. Typhimurium-inoculated cantaloupe (food-fly transmission); or 3) a single SF with four CF with and without fresh cantaloupe (fly-fly transmission, with and without food). Our results indicate that S. Typhimurium multiplies on cantaloupe, S. Typhimurium is transferred to and acquired from cantaloupe by flies, and the presence of cantaloupe facilitates fly to fly transmission. Understanding bacterial transmission between flies and food can help in assessing the role flies play in health and food safety for this pathogen.