Seasonal Abundance of Total and Pathogenic Vibrio parahaemolyticus Isolated from American Oysters Harvested in the Mandinga Lagoon System, Veracruz, Mexico: Implications for Food Safety

Abstract

The abundance of total and pathogenic Vibrio parahaemolyticus (Vp) strains in American oysters (Crassostrea virginica) harvested in two different harvest sites from the Mandinga lagoon System was evaluated monthly for 1 year (January through December 2012). Frequencies of species-specific genes and pathogenic genes exhibited a seasonal distribution. The annual occurrence of Vp with the species-specific tlh gene (tlh(+)) was significantly higher during the winter windy season (32.50%) and spring dry season (15.0%), with the highest densities observed during spring dry season at 283.50 most probable number (MPN)/g (lagoon bank A, near human settlements), indicating the highest risk of infection during warmer months. Pathogenic Vp tlh(+)/tdh(+) frequency was significantly higher during the winter windy and the spring dry seasons at 22.50 and 10.00%, respectively, with highest densities of 16.22 and 41.05 MPN/g (bank A), respectively. The tlh/trh and tdh/trh gene combinations were also found in Vp isolates during the spring dry season at 1.25 and 1.3%, respectively, with densities of 1.79 and 0.4 MPN/g (bank A), respectively. The orf8 genes were detected during the winter windy season (1.25%) with highest densities of 5.96 MPN/g (bank A) and 3.21 MPN/g (bank B, near mangrove islands and a heron nesting area). Densities of Vp tdh(+) were correlated (R(2) = 0.245, P < 0.015) with those of Vp orf8(+). The seasonal dynamics of Vp harboring pathogenic genes varied with seasonal changes, with very high proportions of Vp tdh(+) and Vp orf8(+) isolates in the winter windy season at 46.2 and 17.0%, respectively, which suggests that environmental factors may differentially affect the abundance of pathogenic subpopulations. Although all densities of total Vp (Vp tlh(+)) were lower than 10(4) MPN/g, thus complying with Mexican regulations, the presence of pathogenic strains is a public health concern. Our results suggest that total Vp densities may not be appropriate for assessing oyster contamination and predicting the risk of infection. Evaluation of the presence of pathogenic strains would be a better approach to protecting public health.

Temporal and Spatial Variation in the Abundance of Total and Pathogenic Vibrio parahaemolyticus in Shellfish in China

“…The highest levels of trh- and ORF8-positive V . parahaemolyticus were found in the winter in other similar study [40]; this result may be related to the uneven contribution of pathogenic samples throughout the year. Therefore, the winter cannot be considered an absolutely safe season.…”

Crecimiento y sobrevivencia de Vibrio parahaemolyticus en ostión americano (Crassostrea virginica) almacenada en refrigeración

“…La amplificación de los genes no patogénicos tlh+, patogénicos tdh+ y trh+ y potencialmente pandémico orf8+ de V. parahaemolyticus aislados de ostiones almacenados a 7 °C representa un problema de salud debido al riesgo potencial por el consumo de ostión crudo en la región. Las densidades detectadas de V. parahaemolyticus tlh+ y trh+ al inicio del almacenamiento (tiempo 0) (1.133 y 0.477 log 10 NMP/g) fueron similares a las reportadas en la época de invierno por Flores y colaboradores 28 en 2012 en la misma zona de extracción y estación del año, con densidades de V. parahaemolyticus tlh+, tdh+ y orf8+ de 1.477, 1.197 y 0.773 log 10 NMP/g, respectivamente. El aislamiento de V. parahaemolyticus en dos años consecutivos indica que la bacteria es endémica en el SLM.…”

“…27 Los resultados de estudios recientes de los autores de este artículo muestran las mayores densidades de cepas patogénicas durante primavera e invierno. 28 Dados la capacidad de V. parahaemolyticus de adaptarse a bajas temperaturas y el riesgo a la salud que representa la presencia de este patógeno en el ostión debido a su consumo en crudo, el presente trabajo tuvo por objeto evaluar la presencia de las densidades totales (tlh+) y patogénicas (tdh+, trh+, orf8+) de V. parahaemolyticus en ostión americano (Crassostrea virginica) durante el almacenamiento refrigerado a 7 °C, para determinar el efecto de esta temperatura en el crecimiento y sobrevivencia de V. parahaemolyticus por el riesgo a la salud pública que su consumo representa.…”

“…La metodología empleada para el aislamiento y cuantificación de V. parahaemolyticus se realizó por NMP-PCR (número más probable -reacción en cadena de la polimerasa) de acuerdo con Flores y colaboradores. 28 Los aislamientos presuntivos de V. parahaemolyticus se confirmaron mediante la presencia del gen tlh especie-específico. La presencia del gen tlh y de los genes tdh y trh se determinó mediante PCR multiplex según Bej y colaboradores 8 y la presencia del gen orf8 se determinó por separado de acuerdo con Myers y colaboradores.…”

Seasonal abundance of Vibrio cholerae non O1/non O139 chxA+ in oysters harvested in a coastal lagoon of Mexico's Gulf coast: A seafood safety risk concern

“…cholerae detection from oyster samples was accomplished by MPN-PCR (most probable number-polymerase chain reaction) methodology for rapid detection of the quantity of V. cholerae (Flores-Primo et al, 2014;Luan et al, 2008): Reagents. Primers were provided by SIGMA-ALDRICH QUIMICA S.A de C.V.; Deoxynucleotides Triphosphates (dNTPs), GoTaq ® DNA Polymerase, Fig.…”