Antimicrobial Neutralization Ability of Buffered Peptone Water Compared to Neutralizing Buffered Peptone Water on Salmonella-inoculated Broiler Carcasses

Introduction: The United States Department of Agriculture (USDA) recently amended the protocol for poultry testing to utilize neutralizing buffered peptone water (nBPW) as the rinse fluid for broiler carcass pathogen testing in an effort to improve the capacity for pathogen detection during routine testing. Application of antimicrobial interventions during poultry harvest may interfere with the detection of microbial pathogens due to carryover of antimicrobials into carcass rinse solutions.

Purpose:   The purpose of this study was to compare the antimicrobial neutralizing ability of BPW versus nBPW on broiler carcasses inoculated with a mixture of antibiotic-resistant Salmonella enterica serovars.

Methods:   Young broiler carcasses were collected and inoculated with a Salmonella inoculum containing serovars Typhimurium, Enteritidis, and Heidelberg, resistant to 100.0 µg/ml rifampicin, at 6.0±0.4 log CFU/ml. Inoculated carcasses were treated by peracetic acid (PAA; 0.2%) or cetylpyridinium chloride (CPC; 0.8%) rinse, or a CPC rinse followed by 80 min ice-water bath (CPC₈₀; 0.8%) (n=5). Following antimicrobial application and a water rinse (50±5 ml), carcasses were drip-dried for one minute and rinsed in 100 ml BPW or nBPW. After rinsing, rinse fluids were collected and subjected to USDA-prescribed Salmonella detection procedures.

Results: Only 53.3% of the PAA-BPW-treated carcasses were presumptively positive for Salmonella, while all other treatments (PAA-nBPW, CPC-BPW, CPC-nBPW, CPC₈₀-BPW, CPC₈₀-nBPW) returned 100% of samples Salmonella-positive. The effectiveness of BPW was lower (P<0.001) than nBPW in capacity to neutralize antimicrobials on broiler carcasses. The rinse fluid by antimicrobial intervention combination BPW-PAA had lower (P<0.001) Salmonella detection than all other combinations of rinse fluids and antimicrobials.

Significance: Use of nBPW is anticipated to increase pathogen detection from poultry carcasses treated with antimicrobial interventions, though food safety impacts of nBPW use in routine testing remain unknown.