First detection of Salmonella spp. in backyard production farms from central Chile

Objective The purpose of this study was to detect the presence of circulating Salmonella spp. on backyard production systems (BPS) with poultry or swine breeding in central Chile Introduction Characteristics and conditions of backyard production systems (BPS) transform them into potential maintainers of priority zoonotic agents, like Salmonella spp., highly important agent because of its impact in animal and public health (1). Methods A stratified and proportional random sampling approach was performed (2), based on 15 provinces from the study area (regions of Valparaiso, Metropolitana and LGB O’Higgins). 329 BPS sampled (equivalent to 1,744 samples). Stool content inoculated in test tubes with peptone water (APT, Difco®) supplemented with Novobiocin (Sigma®), incubated for 18 to 24 hours at 37° C. Subcultured on modify semisolid Rappaport Vassiliadis (MSRV, Oxoid®) agar supplemented with Novobiocin, incubated for 24 to 48 hours at 41.5° C. Samples compatible with growth and/or diffusion were sub-cultured by exhaustion on Xylose Lysine Deoxychocolate (XLD, Difco®) agar and then incubated for 24 hours at 37° C (3). Confirmation made by conventional PCR for invA genes (4). Serotypes were predicted using a combination of PCR and sequencing, aimed directly at genes coding for O, H1 and H2 antigens (5). Results 1,744 samples were collected belonging to the 329 BPS. 15 positive BPS (4.6%) detected. Serotypes detected correspond to Salmonella Typhimurium (21.7%), followed by Salmonella Enteritidis (13.0%) and Salmonella Infantis (13.0%), Salmonella Hadar or Istanbul (8.7%), Salmonella [z42] or Tenessee (4.4%), Salmonella Kentucky (4.4) and unknown (34.8%) (Table 1). Conclusions This is the first evidence of serotypes of Salmonella spp. circulating at a regional level in BPS from central Chile. A relevant pathogen for public health.