Reduction of Salmonella Infantis on skin-on, bone-in chicken thighs by cetylpyridinium chloride application and the impact on the skin microbiota

Abstract

Salmonella Infantis has been the etiological agent of numerous foodborne outbreaks of nontyphoidal Salmonella. Consequently, there is an emergent need to mitigate Salmonella Infantis among poultry. Thus, this study evaluated the efficacy of cetylpyridinium chloride (CPC) versus peroxyacetic acid (PAA), on bone-in, skin-on chicken thighs for the reduction of Salmonella and changes in the microbiota. Exactly 100 skin-on, bone-in chicken thighs (2 trials, 0 and 24 h, k = 5, n = 5, N = 50) were inoculated with 108 CFU/mL of a nalidixic acid resistant strain of S. Infantis for an attachment of 106 CFU/g. Thighs were treated with 20 s part dips (350 mL): a no inoculum, no treatment control (NINTC); no treatment control (NTC); tap water (TW); TW+CPC; TW+PAA. Following treatment, thighs were rinsed in 150 mL of nBPW, and rinsates were collected. Rinsates were spot plated for Salmonella and aerobic bacteria (APC). Log10 transformed counts were analyzed using a mixed-effects model (random effect = trial) with means separated using Tukey's HSD (P ≤ 0.05). The genomic DNA of rinsates was extracted, and the 16S rDNA was sequenced on an Illumina MiSeq. Microbiota data were analyzed using QIIME2, with data considered significant at P ≤ 0.05 (main effects) and Q≤0.05 (pairwise differences). Treatment × time interactions were observed for both Salmonella and APC (P < 0.05). The treatment of thighs with PAA and CPC reduced Salmonella and APC in respect to the controls. Numerically, thighs treated with CPC had less Salmonella (4.29 log10CFU/g) and less APC (4.56 log10CFU/g) at 24 h than all other treatments (P > 0.05). Differences in diversity metrics were not consistently observed between treatments; however, in trial 2, the NTC treated thighs were different than those treated with CPC (P < 0.05; Q < 0.05). In both trials, ANCOM, the analysis of microbiome compositional profiles, revealed shifts at both the phylum and order levels with thighs being different in the relative abundances of Proteobacteria (P < 0.05). In conclusion, treatment of skin-on poultry parts with CPC may reduce the risk of foodborne outbreaks caused by Salmonella Infantis.