Prevalence of Arcobacter species in Texas Gulf Coast oysters and water

Abstract

Arcobacter species have been recently suggested as foodborne pathogens. Although little is known about the transmission of arcobacters to humans, contaminated water has been cited as the most common risk factor associated with Arcobacter illness. Arcobacters have been isolated from a variety of water sources in several countries, including the United States, and have recently been recovered from brackish water. The distribution of Arcobacter species in shellfish remains unknown. Analyses of 168 oyster and 120 water samples for Arcobacter species from 7 different locations throughout Galveston Bay, Texas, were conducted from October 2001 until January 2002. The initial 30 oyster and 20 water samples were obtained from two private leases and were analyzed using the recently developed JM protocol. The remaining 138 oyster and 100 water samples were harvested from three approved and two conditionally approved areas and were evaluated utilizing an m-PCR assay. No arcobacters were found. There is no standard protocol for the isolation of Arcobacter spp., so the JM protocol was evaluated for its usefulness for isolation from oysters and bay water. In a comparison study of pork, poultry, oysters, and bay water, this method proved unsuitable for oysters and bay water, as all JM agar plates were completely overgrown by contaminants, including species from the genera Stenotrophomonas, Vibrio, Acientobacter, Sphingomonas, Psuedomonas, and Aeromonas. The pinpoint colonies typical of arcobacters were not visible. Since the JM method was unsuccessful, an m-PCR assay developed for detection in poultry was evaluated as an alternative method. In a comparison study of the two methods, no differences were found between pork and poultry samples tested, indicating that the m-PCR was equally suitable for identification. The detection level of the m-PCR assay was determined to be 10³ cfu g⁻¹ oyster. Lack of Arcobacter species detection might be attributed to several factors, including absence of arcobacters, sub-optimal environmental conditions, lack of method sensitivity, and competition from indigenous microflora. Further analysis needs to be conducted to elucidate the true prevalence of these microorganisms in this environment. This research is the first known attempt to determine the prevalence of Arcobacter species in shellfish.