Environmental ocurrence of Salmonella Dublin in Midwest U.S. dairy-beef operations: Associations with biosecurity and farm management
Year: 2026
Type: article
Abstract: Salmonella Dublin ( S . Dublin) affects both cattle health and public safety due to its host adaptation, antimicrobial resistance, and persistence in subclinical carriers. Although well documented in dairy systems, its epidemiology in U.S. dairy-origin cattle raised for beef (dairy-beef) remains understudied. To design and validate a multiplex PCR (mPCR) assay for environmental detection of S . Dublin, apply mPCR alongside culture to estimate environmental occurrence in dairy-beef farms, and identify farm-level practices associated with detection. Previously described S . Dublin targets were screened in silico and analytically validated in vitro. A cross-sectional study was conducted on 65 convenience-sampled Midwest dairy-beef farms. Environmental boot swabs (n = 265) were tested using mPCR and culture. Farm- and sample-level positive proportions were estimated using Bayesian beta-binomial models accounting for unequal sampling. Farm-level predictors were evaluated using multivariable negative binomial regression with an offset for total samples collected per farm. The mPCR assay showed high analytical specificity; only serovar Dublin isolates produced the complete three-target profile. In field samples, mPCR detected S . Dublin on 35.4% of farms versus 6.2% by culture. The overall proportion of mPCR-positive environmental samples across the sampled operations was 11.1% (95% CrI: 3.8–20.6%). Detection was significantly higher on farms with frequent calf introductions and where employees had regular contact with outside livestock. In this sampled population, environmental occurrence of S . Dublin was common and associated with calf movement frequency and personnel contact patterns. The validated mPCR supports targeted environmental surveillance to inform biosecurity efforts in dairy-beef systems. • Salmonella Dublin was detected on 35% of enrolled Midwest dairy-beef farms using environmental boot swabs. • Multiplex PCR (mPCR) identified Salmonella Dublin in the environments of more farms than culture. • Environmental contamination with S . Dublin was detected across pre- and post-weaned areas, including the milk-mixing room. • Frequent calf introductions and employee contact with outside livestock increased the likelihood of S . Dublin detection in farm environments.
Source: Preventive Veterinary Medicine
Institution: The Ohio State University
Language: English
Subfield: Food Science
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,280
Award: G807043998
OpenAlex ID: W7154683614