| dc.description.abstract | Salmonella has remained a persistent public health concern in the United States, despite robust food protection programs. Additionally, the spread of antibiotic resistance has created complications in the treatment of salmonellosis. The objective of these studies was to obtain a survey of poultry products to evaluate prevalence and antibiotic resistance of Salmonella, then test the isolates recovered for phenotypic traits that may relate to their survival through to the retail market. Seventy-four poultry products consisting of cut up parts, ground product, and giblets were collected from multiple groceries, categorized by labeled antibiotic usage such as conventional, no antibiotic ever (NAE), organic, or other. Salmonella was isolated from these products using a combination of 3 different enrichment and 3 different isolation media, resulting in 9 total media pathways with the goal of isolating as many Salmonella serovars as feasible. Isolates were confirmed as Salmonella using PCR and whole genome sequencing, before undergoing antimicrobial susceptibility testing. A subset of these Salmonella isolates was then tested for biofilm formation, pH resistance, and PAA minimum inhibitory concentration. The prevalence of Salmonella among the 74 meat samples was 35.1%. The majority of isolates, 88%, possessed resistance to at least one class of antibiotics, and 86.4% were resistant to three or more classes of drugs. No class of antibiotics was more or less likely to display resistance. The most resisted drug was tetracycline, and the most common serovar was Infantis. All tested isolates were capable of forming biofilms and displayed resistance to PAA and pH. Both strains of S. Enteritidis displayed strong biofilm formation abilities, both strains of S. Typhimurium displayed moderate biofilm formation, while S. Infantis had one strain with a moderate biofilm formation ability and one strain with a weak biofilm formation ability. The minimum inhibitory concentration of PAA was reduced when strains were exposed to acidic conditions prior to PAA treatment, but this effect was weaker if OH was incorporated into the PAA. This effect was consistent across serovar and strain, which were not statistically significant at determining the MIC of PAA. S. Infantis displayed a clear increase in resistance to low pH when pre-exposed to a sub-lethal acidic pH, while the same sub-lethal pH decreased resistance to acidic conditions in both S. Enteritidis and S. Typhimurium. This suggests that S. Infantis displays a more pronounced acid-shock response than other tested serovars. Salmonella isolates demonstrate resistance profiles that may contribute to their persistence in the retail market, and the isolates that are present have high levels of antibiotic resistance that can complicate treatment. Drug resistant Salmonella are commonly found in retail markets and consist of serovars known to cause human illness. Programs aiming to improve public health should focus on targeting serovars that survive to reach the retail market, as these are the bacteria that consumers will be exposed to. Understanding the phenotypic resistance profiles of serovars present in the retail market will enable a targeted response and adjustment of antimicrobial interventions that can reduce the risk of infection from products. | en_US |
