Abstract

Title: Phenotypic Comparison of Salmonella Phage Isolated from Open versus Close Animal Production Systems Authors: Dácil Rivera, Fernando Dueñas, Rodolfo Tardone, Viviana Toledo, Christopher Hamilton-West, Andrea Moreno Switt. Introduction: The genus Salmonella represent a worldwide distributed pathogen that can be transmitted to humans mainly as foodborne or by contact with infected animals. Salmonella diversity is represented by 2,600 serovars, which show geographic and animal host distribution. Bacteriophages are abundant and widely distributed; through constant host lysis, phage play important roles driving host diversity. The ability of phages to lyse different hosts can be tested, this allowing to evaluate the affinity of phages in a given environment to certain Salmonella serovars, through of Host range test. Purpose: The purpose of this study was to compare the host range of Salmonella phages obtained from open and closed animal systems in Chile Methods: We isolated Salmonella and phages; for phage isolation we used as host the predominant Salmonella serovar in Chile (Enteritidis, Typhimurium, Infantis, and Heidelberg). Our study systems included i) backyard poultry and pigs (n=35), ii) industrial pigs (n=36), iii) backyard cattle (n=47), iv) industrial cattle (n=160), v) wild bird in peri – urban locations (n=49), vi) wild bird – wetland (n=271), and vii) backyard – South American camelids (n=49). The host range was characterized with a panel of 23 Salmonella serovars and analyzed through hierarchical clustering. Narrow host range was defined for phages lysing 1–4 hosts, and wide host range for phages lysing 5–23 hosts. Results: Salmonella was found in all systems, except for industrial cattle. Phages were isolated in all systems in a proportion of three times more often than Salmonella (93 Salmonella versus 322 phages). Phage host range differ by system, the widest host range was found in backyard cattle, wild bird – wetland, backyard poultry, all open systems with low human intervention. While in close systems, phages lysed Salmonella serovar commonly associated with human cases; contrastingly the open systems lysed serovars not frequently isolated in Chile. Significance: This is the first study that conduct a wide comparison of Salmonella and its phages in different animal systems. Differences described here could indicate the potential application of using phages as prediction tools to investigate Salmonella diversity.