Project description:Shrimp are an important and valuable commodity for aquaculture that are widely traded internationally. Widespread antibiotic use has been documented in shrimp farming and is a common source of criticism of aquaculture products. Additionally, previous reports have found some evidence of antibiotic residues in shrimp samples obtained from retail stores in the United States, which is a concern for consumers. To further understand the prevalence of antibiotics in retail shrimp in the United States, shrimp samples obtained from grocery stores across 16 states were analyzed for 74 antibiotic compounds/metabolites at a commercial laboratory. 68 samples were analyzed for a multiclass antibiotic panel which included 66 antibiotics while a subset of 15 samples were analyzed for β-lactam antibiotics, Nitrofurans, and Oxytetracycline. Samples were obtained that were labeled as being from major production countries, including India, Indonesia, Thailand, and Vietnam. No detectable antibiotic residues were found in this survey in any samples. This is contrary to previous findings in frozen shrimp analyzed for antibiotics, which typically report low levels of the prevalence of antibiotics.
Project description:Persistence of Listeria monocytogenes in retail deli environments is a serious food safety issue, potentially leading to cross-contamination of ready-to-eat foods such as deli meats, salads, and cheeses. We previously discovered strong evidence of L. monocytogenes persistence in delis across multiple states. We hypothesized that this was correlated with isolates’ innate characteristics, such as biofilm-forming capacity or gene differences.We further chose four isolates for RNA-sequencing analysis and compared their global biofilm transcriptome to their global planktonic transcriptome. Analysis of biofilm vs planktonic gene expression did not show the expected differences in gene expression patterns. Overall, L. monocytogenes persistence in the deli environment is likely a matter of poor sanitation and/or facility design, rather than isolates’ biofilm-forming capacity, sanitizer tolerance, or genomic content