A study by North Carolina State University studied the persistence of antimicrobial-resistant (AMR) Salmonella in residential broiler production systems and made comparisons with commercial systems. Ten backyard and 10 commercial farms were sampled at three time points across bird production. Both fecal (n = 10) and environmental (soil, n = 5, litter/compost, n = 5, feeder and waterer swabs, n = 6) samples were collected at each visit on days 10, 31, and 52 of production for backyard farms and days 10, 24, and 38 of production for commercial farms. Salmonella was more prevalent in commercial farm samples (52.31%) over backyard farms (19.10%). Kentucky was the most common serotype found in both backyard and commercial farms. Multidrug-resistant (MDR, resistance to ≥3 or more antimicrobial classes) isolates were found in both production systems. In contrast, ciprofloxacin- and nalidixic acid-resistant intermediate isolates were more prevalent in commercial (33%) than backyard samples (1%). Plasmids associated with MDR were found in Kentucky and Infantis isolates, particularly IncFIB(K)_1_Kpn3 megaplasmid (Infantis). Our study emphasizes the need to understand the selection pressures in disseminating megaplasmids in MDR Salmonella in distinct broiler production systems. @ https://www.liebertpub.com/doi/10.1089/fpd.2023.0181
