Abstract

Salmonella is a widely distributed zoonotic pathogen that can be transmitted to humans as foodborne or by animal contact. Salmonella has 2,600 serovars that show distinct distribution in different animals and geographic regions; being a few serovars (e.g., Enteritidis) globally distributed. While phages infecting Salmonella are very abundant, our understanding on Salmonella-phage diversity is very limited. The aim of this study was to investigate the diversity of Salmonella -phage systems in different animals and geographic locations in Chile. Salmonella and phages were isolated from samples obtained on continental Chile of 49 llamas and small ruminants, 10 pig farms, 35 backyard poultry, 80 wild birds, and 28 reptiles, 8 dairy farms, along with backyard cows from Eastern Island. Isolates representing the most common serovars (Enteritidis, Typhimurium, Infantis, and Heidelberg) were used to isolate phages. On the isolated phages we tested the host range using i) a set of foreign isolates (26 Salmonella serovars obtained from the US), and ii) a set of native isolates (31 Salmonella obtained from the locations studied above). We have isolated 105 Salmonella isolates (9 from pigs, 31 from poultry, 31 from wild bird, 28 from reptiles, and one from a goat). Phages were more abundant than Salmonella with 201 phage isolates obtained. Most of the phages (40-60%) were isolated in S. Enteritidis, which was also the most susceptible serovar. Host range characterization with foreign isolates displayed that phages show a narrow host range (mean=4 isolates lysed), but with native isolates, phages show a wide host range (mean=13 isolates lysed). All Salmonella of serogroups D were the most susceptible to phages. Clustering also showed a group of widely distributed phages that are very specific to Salmonella of the serogroups D. Phages from remote location as Eastern Island showed distinct host specificity. Salmonella phages appears to be adapted to local isolates; while wide host range and narrow host range phages are co-existing on animals, resistant and susceptible Salmonella are also present indicating a dynamic that need to be further investigated. Author Disclosure Block: D. Rivera: None. F. Duenas: None. R. Tardone: None. C. Caceres: None. V. Toledo: None. C. Hamilton-West: None. A.I. Moreno Switt: None.