Effects of depuration of molluscs experimentally contaminated with Escherichia coli, Vibrio cholerae O1 and Vibrio parahaemolyticus

Abstract

Aims: The aim of the present study was to investigate the behaviour of two pathogenic vibrios (Vibrio cholerae O1 and Vibrio parahaemolyticus) during depuration and to compare it with that of Escherichia coli, used as an indicator of suitability for consumption. Methods and Results: Samples of Mytilus galloprovincialis were experimentally contaminated with E. coli, V. cholerae O1 and V. parahaemolyticus, depurated in a pilot plant using ozone and analysed at selected intervals. Numbers of E. coli and vibrios were estimated using an MPN method. The presence of vibrios was con®rmed by the use of PCR. The target genes used were ctx for V. cholerae O1 and the restriction fragment pR72H for V. parahaemolyticus. There was a substantially smaller reduction in the numbers of both vibrios (approximately 1 log) during the depuration process than of E. coli (approximately 3 log). Conclusions:The results con®rm the inadequacy of E. coli as an indicator that molluscs have been cleansed of other microbiological agents. Signi®cance and Impact of the Study: The study con®rms the risk associated with the consumption of mussels and the need to correctly conserve and cook them prior to consumption.

Evaluation of a Small Scale UV-treated Recirculating Depuration System for Oysters (<i>Crassostrea iredalei</i>)

“…Oysters are usually consumed raw. This leads to the potential risks and transmission of pathogenic microorganisms from contaminated areas [2].…”

“…The consumption of contaminated bivalve shellfish is associated with a number of human diseases, particularly when oysters are ingested as raw [3].Since oysters are filter feeders, they tend to absorb and concentrate pathogenic microorganisms; particularly when the shellfish originated from contaminated areas [2].Seafood is the main source of animal protein by more than a billion people globally, and contaminated seafood is a frequent etiology of diseases contracted from the ocean, including both pathogenic and chemical contamination [4]. Coliform bacteria and Escherichia coli are common indicators of microbiological infection of shellfish and monitoring shellfish contamination.…”

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“…La colecta, manejo y transporte de las muestras se llevó a cabo de acuerdo al criterio establecido en la Norma Oficial Mexicana NOM-109-SSA1-1994. Los organismos incrustados en la concha fueron removidos utilizando cuchillos de acero Fouling organisms were removed from these bodies, using stainless steel knives (Croci et al, 2002;Castañeda et al, 2005). The samples were placed in plastic bags for transport to the laboratory, at an average temperature of 4 ± 1 °C (Da Silva et al, 2003).…”

“…Agarose gels were prepared at 2 %, previously dyed with 3 µL ethidium bromide in an electrophoresis chamber (MaxiCell ec360m Electrophoretic Gel System) to which, inoxidable (Croci et al, 2002;Castañeda et al, 2005). Las muestras fueron colocadas en bolsas de plástico para transportarlos al laboratorio, a una temperatura promedio de 4 ± 1°C (Da Silva et al, 2003).…”

Persistence of Vibrio parahaemolyticus in the Pacific Oyster, Crassostrea gigas, Is a Multifactorial Process Involving Pili and Flagella but Not Type III Secretion Systems or Phase Variation

“…Depuration is a controlled process in which shellfish are placed into clean seawater to reduce the bacterial contaminants in their tissues. However, depuration is not very effective at reducing the numbers of V. parahaemolyticus cells in oysters (3), and little is known about the association of V. parahaemolyticus with oysters.…”