Inhibition and Interactions of Campylobacter jejuni from Broiler Chicken Houses with Organic Acids.

Ross Beier,Kathleen Andrews,Tawni Crippen,Denise Caldwell,Robin Anderson,J. Byrd,David Nisbet

doi:10.3390/microorganisms7080223

Abstract

Campylobacter jejuni is a bacterium that causes major diarrheal disease worldwide and is also one of the top five foodborne pathogens encountered in the United States. Poultry is a major source of C. jejuni, and a high-risk factor for contracting campylobacteriosis. Organic acids are used in the United States during food animal processing for removal of bacterial contamination from animal carcasses. Six organic acids were evaluated in inhibition studies of 96 C. jejuni strains obtained from shoe covers used in broiler chicken houses at different poultry farms in several states by determining the susceptibilities of the C. jejuni strains, along with the pH values at the molar minimum inhibitory concentrations (MICMs). The undissociated and dissociated organic acid concentrations were calculated at the MICMs with the Henderson-Hasselbalch equation. The results for the 96 C. jejuni strains were treated similarly for each different organic acid. Campylobacter jejuni inhibition did correlate with the dissociated organic acids, but did not correlate with pH or with the undissociated organic acids. When the concentrations of dissociated organic acids decreased, the C. jejuni strains were not disinfected. A carcass wash using organic acids should have the concentration of dissociated acid species carefully controlled. It is suggested to maintain a dissociated acid concentration for propionic, l-lactic, formic, citric, butyric, and acetic acids at 24, 40, 36, 21, 23, and 25 mM, respectively, and at these dissociated organic acid levels an acid wash would be expected to remove or inhibit 97% or more of the C. jejuni bacteria studied here. However, studies must be undertaken to confirm that the suggested concentrations of dissociated organic acids are adequate to remove C. jejuni bacteria in the field vs. the laboratory. Due to propionate, l-lactate, formate, butyrate, and acetate being utilized by C. jejuni, these organic acids may not be appropriate for use as a carcass wash to remove C. jejuni surface contamination. Of all tested organic acids, dissociated citric acid was the most efficient at inhibiting C. jejuni.

Highlights

Campylobacter jejuni is a bacterial organism that causes gastroenteritis worldwide [1,2,3,4,5,6]
We evaluated the interactions of six different organic acids (OAs)—propionic, l-lactic, formic, citric, butyric, and acetic—against 96 C. jejuni potential foodborne pathogen strains, while evaluating the effects that pH and the undissociated and dissociated OA species have on the bacteria at their OA MICMs
In our study of C. jejuni inhibition by OAs, the inhibition of strains was associated with the concentration of dissociated propionic, citric, butyric, and acetic acid, and these OAs correlated with the MICMs of 97–100% of the C. jejuni strains tested

Summary

Introduction

Campylobacter jejuni is a bacterial organism that causes gastroenteritis worldwide [1,2,3,4,5,6]. Campylobacter jejuni are Gram-negative bacteria that are non-spore-forming [7] and are known to be a major cause of diarrheal disease in humans [8]. The two main Campylobacter species usually associated with human foodborne illnesses worldwide are C. jejuni and C. coli [2,11,12,13]. These two bacteria have high DNA homology [14], with related or identical antigens [15]. A C. jejuni infective dose of only about 500–800 bacteria are required for infection [25,26]

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Conclusion