The prevalence and mode of persistence of Salmonella on commercial poultry processing equipment was examined in this study. The equipment surfaces of six commercial processing plants were sampled over three-time periods designated as A (after processing), B (after cleaning), and C (after sanitization) and each plant was visited three times. Salmonella prevalence was greater (p<0.0001) at time A than times B and C, while there were no differences (p=0.386) between times B and C. A total of twentyive Salmonella isolates from five distinct serovars were recovered from the processing plants. Further examination of the recovered isolates showed that tolerance to sanitizing agents (chlorine and quaternary ammonium compounds, QAC) and/or biofilm formation was the possible mode of persistence. In addition, all the isolates were resistant to multiple antibiotics in different classes of drugs and more than two genes that are responsible for ⅰ). biofilm formation, ⅱ). resistance to QAC, ⅲ). oxidative stress response, and ⅳ). resistance to antibiotics were detected. Three selected isolates were further characterized based on virulence factors and antimicrobial resistance using whole genome sequencing (WGS) to possibly predict phenotypic characteristics. The WGS data correlates with phenotypic characteristics that were previously observed in the isolates including the ability to produce biofilms and resistance to antibiotics including β-lactams, aminoglycosides, and cephalosporins. WGS predicted the isolates carried resistance genes for antibiotic drug classes that were not observed phenotypically. These include macrolides and fluoroquinolone, which is a concern due to its use in treating foodborne infection. Furthermore, the genome of the three selected isolates were predicted to have over sixty virulence genes that allow Salmonella to invade, attach, and colonize the host cells. The results from this study suggest that the antimicrobials used for sanitization may be insufficient to inactivate Salmonella because of the ability to produce biofilms on processing surfaces. Most importantly, the results suggest the ability of the isolates to cause infection in humans meaning if contamination were to occur, the right antibiotic treatment could be a challenge. Further research is imperative to determine the effective antimicrobial for Salmonella biofilms.

Salmonella enterica Typhimurium is a common foodborne pathogen, and ready-to-eat (RTE) seafood is a potential source of Salmonella outbreaks. Lactic acid is a classical preservative in the meat industry and it is used with high efficacy to sanitize meat surfaces. Cetylpyridinium chloride (CPC) is a cationic quaternary ammonium compound proposed for use as a pathogen intervention substance. Cetylpyridinium chloride activity can be potentially affected by interactions between cetylpyridinium chloride and lactic acid. Lactic acid treatment (up to 1%) reduced Salmonella Typhimurium counts by less than 0.5 log cfu/g. Cetylpyridinium chloride treatment (up to 1%) reduced Salmonella Typhimurium counts by 0.9 log cfu/g. Cetylpyridinium chloride treatment at 18 and 45°C reduced populations of Salmonella Typhimurium by 1.34 and 1.14 log cfu/g. Combined treatment with cetylpyridinium chloride and lactic acid at 18 and 45°C decreased Salmonella Typhimurium counts by 0.83 log cfu/g and 1.05 log cfu/g. The single intervention of cetylpyridinium chloride was more effective than lactic acid used alone or combination of cetylpyridnium chloride and lactic acid to reduce Salmonella Typhimurium attached on ready-to-eat shrimp.

Water and a copper sulfate (CSL) solution at 27, 57 and 88°C; steam pasteurization and dielectric heating were analyzed on their effect in reducing microbial load (APC) and Salmonella Typhimurium on inshell pecans (Carya illinoinensis). The CSL solution (more effective than water alone) reduced APC by 1.5 (300 s), 2 (60 s) and 4.0 (60 s) log CFU/g at 27, 57 and 88°C, respectively; and Salmonella by 3.0 log at 27°C in 60 s. Steam reduced APC by 3.7 log in 180 s and Salmonella by 4.0 log CFU/g in 30 s. Dielectric treatment reduced APC by 3.0 log and Salmonella by 4.5 log CFU/g in 60 s. Most treatments had no effect on the pecan shell or the nut quality, except for dielectric heating, which gave a slight "roasted" or "burnt" flavor to the nuts. This study showed that a proper antimicrobial-hot water treatment, steam or dielectric heating will be effective in "pasteurizing" pecans, resulting in a safe and wholesome product.

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