Concentration-dependent Neutralization of Antimicrobials Used in Poultry Processing Allowing Survival of Campylobacter spp.

Introduction: Antimicrobials applied to poultry carcasses during harvest and fabrication may result in residues of antimicrobials being carried over into carcass rinsing fluid, decreasing the likelihood of pathogen detection during routine testing. Antimicrobial neutralizers, when used, may assist the detection of pathogens, like Campylobacter spp., on fresh poultry.

Purpose: The purpose of this study was to test the abilities of antimicrobial-specific neutralizers applied, at systematically increasing concentrations, to cetyl pyridinium chloride (CPC)- or peracetic acid (PAA)-exposed Campylobacter jejuni to determine minimum neutralizer concentrations necessary to allow pathogen survival.

Methods: Campylobacter jejuni were inoculated to a target of approximately five log CFU/ml in double strength Mueller Hinton Broth (2X MHB) and, then, immediately exposed to CPC at 0.1 to 0.8% (w/v; final concentration), or PAA at 0.0125 to 0.2% (0.2%=2,000 ppm; final concentration). For CPC, a combination of lecithin and Tween 20 was added to buffered peptone water (BPW) at 0.125 to 2.0X their standard concentrations in Dey-Engley (D/E) Neutralizing Buffer. For PAA, disodium phosphate (Na₂HPO₄) and potassium monophosphate (KPO₄) were added at 0.25 to 3.0X their standard concentrations in BPW. Sodium thiosulfate was also added at 0.15 to 1.8% (w/v) to neutralize peroxy-radicals. Test tubes were incubated for 24 h at 35°C and, then, inspected for turbidity as indicative of pathogen growth or inhibition.

Results: At 0.8% CPC, 1X CPC-neutralizer additions were required to observe growth for Campylobacter isolates across replicates. Conversely, for PAA the addition of neutralizers to the 2X application was required to allow Campylobactersurvival at 2,000 ppm applied PAA.

Significance: Increasing concentrations of sanitizers consistently required higher concentrations of neutralizers to counteract sanitizer antimicrobial activity, allowing Campylobacter growth and detection. Antimicrobial neutralizers, when added to poultry rinsing fluids, may improve the detection of viable Campylobacter from fresh poultry.