Prevalence and antimicrobial resistance patterns of Salmonella isolated from poultry farms in southeastern United States

Authors: VELASQUEZ, C - Purdue University; MACKLIN, K - Purdue University; KUMAR, S - University Of Georgia; BAILEY, M - Purdue University; EBNER, P - Purdue University; OLIVER, H - Purdue University; MARTIN-GONZALEZ, F - Purdue University; SINGH, M - University Of Georgia

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2018
Publication Date: 6/1/2018
Citation: Velasquez, C.G., Macklin, K.S., Kumar, S., Bailey, M., Ebner, P.E., Oliver, H.F., Martin-Gonzalez, F.S., Singh, M. 2018. Prevalence and antimicrobial resistance patterns of Salmonella isolated from poultry farms in southeastern United States. Poultry Science. 97(6):2144-2152. https://doi.org/10.3382/ps/pex449.
DOI: https://doi.org/10.3382/ps/pex449

Interpretive Summary: Salmonella is the most common food-borne pathogen that has been associated with poultry and poultry products. Its’ impact on public health is sever and more specifically resistance to antimicrobials can make it challenging to treat patients with salmonellosis. This study determined the antimicrobial resistance of Salmonella from poultry as it related to on-farm practices including biosecurity. Changes to biosecurity practices were suggested to the farmers and Salmonella prevalence was determined to evaluate the effective of these changes. Four poultry farms were sampled by collecting samples from the farm that included samples from chickens and the farm environment. Prevalence of Salmonella was 3-4% during pre-recommendations and ranging from 5-14% post-recommendations. Seven percent of the Salmonella isolates exhibited resistance to at least one of the eight antimicrobials tested. One isolate of exhibited multidrug resistance (3 different antibiotics). Results suggest that irrespective of implementation of improved biosecurity practices, seasonal variation can cause changes in the prevalence of Salmonella on the farms and resistance to clinically important antimicrobials used to treat salmonellosis is a concern to public health.

Technical Abstract: Salmonella spp. are among the most common foodborne pathogens, and increase in the occurrence of antimicrobial drug-resistant Salmonella poses a severe risk to public health. The main objective of this study was to determine changes in Salmonella prevalence and their antimicrobial resistance on poultry farms following recommendations to changes in biosecurity practices. Four poultry farms were sampled by collecting cloacal swabs, drag swabs, and litter samples prior to recommended biosecurity changes (March–April) and post recommendations (October– November). Prevalence of Salmonella was 3 to 4% during pre-recommendations, while the prevalence was higher (P > 0.05), ranging from 5 to 14% during post recommendations. Higher Salmonella prevalence was observed for pre- and post-recommendation phases by sample type in cloacal and drag samples -5% for farm 1, drag swab -6% on farm 2, cloacal swab -6% for farm 3, and drag swab -17% on farm 4. The PCR confirmed Salmonella were serotyped and tested for antimicrobial resistance. Six serotypes of Salmonella were identified with S. Enteritidis (52%) being the most prevalent, followed by S. Berta (38%), S. Mbandaka (7%), S. Typhimurium (2%), S. Kentucky (0.4%), and S. Tennessee (0.4%). A total of 7% isolates exhibited resistance to at least one of the 8 antimicrobials. Higher resistance was observed for tetracycline, streptomycin, and nalidixic acid. A single isolate of S. Mbandaka exhibited multidrug resistance to tetracycline, amoxicillin/clavulanic acid, and ampicillin. Based on these prevalence results, it can be inferred that, irrespective of implementation of improved biosecurity practices, seasonal variation can cause changes in the prevalence of Salmonella on the farms. Resistance to clinically important antimicrobials used to treat salmonellosis is a concern to public health.