Survival persistence of the 3 common Salmonella enterica serotypes isolated from broilers' in different matrices

Broiler meat is the predominant source of Salmonella as a foodborne pathogen. Several control strategies have focused on the reduction of Salmonella spp. levels at different production stages. However, the persistence of Salmonella between consecutive flocks is still of great concern. This study was designed to under-stand the cause of reinfection in broiler flocks due to sur-vival of Salmonella in feeding lines of related matrices. Salmonella (S.) Enteritidis, S. Infantis, and S. Typhimu-rium isolated from broiler farms in North-West Germany were used. Four types of matrices (phosphate buffer saline (PBS), dietary plant fat, fat with feed mixture, and feed) were applied to evaluate Salmonella survival (with the ini-tial dose about 8.0 log10 CFU/mL) during a simulation of 4 production cycles. To evaluate the growth and survival status of Salmonella ISO 6579-1:2017 were performed (quantitatively by plate count method (PCM) and most probable number method (MPN)) and qualitatively) at 5 defined time points (x2802;7, 0, 4, 7, and 35 d). In all matri- ces and for the 3 serovars, the Salmonella count decreased at the end of the fourth cycle in comparison to the begin-ning of the experimental infection, and was still cultivated except for fat matrix. The PBS matrices showed the high-est survival level of Salmonella and did not decline drasti-cally by the end of the fourth cycle (5.93 0.00, 5.87 0.02, 5.73 0.05 log10 CFU/mL, respectively). However, the fat matrices showed the lowest survival level for the 3 isolates at d 35 since the first cycle (0 log10 CFU/mL using PCM). Regarding the fat-feed mixture, and feed matrices, there was a fluctuation in the survival rate of Salmonella (all serovars) within each cycle. For the qualitative method, the 3 serovars persisted in all matrices until the end of the fourth cycle except for fat matrices. The pres-ent study highlights the ability of Salmonella to survive for a long time in different temperatures and matrices despite efficient cleaning and disinfection processes in the feeding lines, which may influence reinfection with Salmo-nella in poultry houses.