Development of a Quantitative Methodology to Estimate the Number of Enteropathogenic Campylobacter on Fresh Poultry Products
While there are numerous infectious agents associated with food-borne infection and intoxication, the major pathogens of concern to consumer safety, i.e., cause the greatest threat from disease for humans, are Campylobacter jejuni/coli, Salmonella spp., Escherichia coli 0157:H7, and Listeria monocytogenes 3–6,10,12–14. The currently accepted methodologies for qualitative (and, where available, quantitative) analyses are at best: slow, cumbersome, costly, and manpower intensive. For example, the currently accepted “gold standard” method for quantitation of Salmonella spp. is the most probable number test (MPN), an analytical method with which additional drawbacks are recognized13–15. At best, the MPN provides an estimate of a range of statistically probable numbers, not an exact count, of specific viable target microorganisms contained in a given unit sample. Also, the MPN is only as reliable as the ability of the selective broth medium to support detectable growth of as few as one cell. To obtain this MPN estimate, the sample has to be serially diluted in such a manner that a more dilute sample will result in fewer positive tubes as indicated by growth and specific isolation and confirmation tests for the target organism. These requirements are not readily achievable for the enteropathogenic campylobacters, given their fastidious nature1. Direct spread plating and filtration techniques frequently have been applied to the task of isolating and semi-quantifying campylobacters from environmental sources1,2,7–9,16, but applications for rapid detection and enumeration from food sources have not been developed. Our laboratories’ objective was to develop an alternative approach(es) to the existing methodologies, e.g., MPN, in an effort to quantify the four target pathogens, Campylobacter jejuni/coli, Salmonella spp., Escherichia coli 0157:H7, and Listeria monocytogenes in raw meat and poultry samples.
KeywordsMuch Probable Number Sample Wash Mixed Cellulose Ester Poultry Carcass Target Coloni
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