In-vitro synergistic effects of peracetic acid and biocides approved for use in poultry meat processing against four serotypes of non-typhoidal Salmonella enterica

Authors: McMillan, Elizabeth; Read, Quentin; Mitchell, Trevor; Harris, Caitlin; Glenn, Anthony; Pokoo-Aikins, Anthony; Meinersmann, Richard; Frye, Jonathan

Submitted to: Microbiology Spectrum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2025
Publication Date: 9/11/2025
Citation: Mcmillan, E.A., Read, Q.D., Mitchell, T.R., Harris, C.E., Glenn, A.E., Pokoo-Aikins, A., Meinersmann, R.J., Frye, J.G. 2025. In-vitro synergistic effects of peracetic acid and biocides approved for use in poultry meat processing against four serotypes of non-typhoidal Salmonella enterica. Microbiology Spectrum. https://doi.org/10.1128/spectrum.00652-25.
DOI: https://doi.org/10.1128/spectrum.00652-25

Interpretive Summary: Contaminated and undercooked chicken and turkey meat are currently estimated to cause about 25% of human Salmonella illnesses. Meat processors utilize multiple sanitizers which have been determined to be "generall regarded as safe" to reduce pathogen contamination in processing plants. The effectiveness of these sanitizers against Salmonella is well documented. However, the effectiveness of these sanitizers used in combination is less understood, despite their frequent serial use in plants. To investigate this, we exposed four serotypes of Salmonella to four sanitizers in serial: peracetic acid (PAA), cetylpiridinium chloride (CPC), calcium hypochlorite (CH), and sodium hypochlorite (SH). While results were highly variable across all serotypes, important conclusions could still be drawn: 1. When applied in combination, order of application significantly impacted PAA tolerance, 2. Application of any non-zero concentration of CH or SH resulted in significantly lower PAA tolerance across all serotypes. 3. Dilution could not be ruled out as the cause of the decrease in tolerance. The results presented in this study are an important tool for planning future confirmation studies on meat products.

Technical Abstract: During poultry meat processing, multiple biocides can be applied to reduce foodborne pathogen contamination. Previous experiments have investigated the efficacy of several biocides, but few have investigated the efficacy of multiple biocides applied in series. Here, we evaluated the synergistic effects of peracetic acid (PAA) in combination with other commonly applied biocides approved for use in U.S. poultry meat processing: cetylpyridinium chloride (CPC), calcium hypochlorite (CH), and sodium hypochlorite (SH). Serotype specific mixtures of Salmonella isolates (serotypes Typhimurium, Enteritidis, Kentucky, and Infantis) were exposed to PAA and biocides, individually and in combination, in 96-well plates using broth culture. Mixtures were exposed to the first biocide for 15 seconds, the second biocide for 15 seconds, and chemical activity was then neutralized with Dey-Engley broth. Across three trials, results were highly variable for all serotypes and combinations tested; however, responses to non-PAA biocides were uniform when applied individually. When applied in combination, order of application significantly impacted PAA tolerance (pd <0.05). Application of any non-zero concentration of CH or SH also resulted in significantly lower PAA tolerance across all serotypes (pd <0.05). Dilution could not be ruled out as the cause of the tolerance or the variability. Variable results highlight the need to test biocides on meat products to accurately evaluate efficacy for poultry meat processing.