Bacterial diversity and potential risk factors associated with Salmonella contamination of seafood products sold in retail markets in Bangkok, Thailand

Abstract

Consumption of contaminated food causes 600 million cases, including 420,000 of fatal infections every year. Estimated cost from food-borne illnesses is USD 110 billion per year, which is an economic burden to low- and middle-income countries. Thailand is a leading producer and consumer of seafood, but little is known about bacterial contamination in seafood. In particular, public health agencies need to know the relationship between Salmonella contamination in seafood and risk factors, as assessed with readily available culture-dependent and bacterial phenotyping methods. To address this, levels of indicator bacteria, Salmonella and Vibrio in various seafood products were determined to identify risk factors associated with Salmonella contamination. A total of 335 samples were collected from October 2018 to July 2019 at seafood markets throughout Bangkok, Thailand; overall sample composition was Pacific white shrimp (n = 85), oysters (n = 82), blood cockles (n = 84), and Asian seabass (n = 84). Prevalence was 100% for fecal coliforms and 85% for E. coli. In contrast, prevalence was 59% for V. parahaemolyticus, 49% for V. cholerae, 19% for V. alginolyticus, 18% for V. vulnificus, and 36% for Salmonella. Highest concentrations of fecal coliforms and E. coli were in oysters. Highest concentrations of Salmonella with Matopeni (31%) being the predominant serotype were in shrimp. Salmonella contamination was significantly associated with type of seafood, sampling location, retail conditions, and the presence of E. coli, V. alginolyticus and V. vulnificus. A cutoff value for E. coli concentration of 1.3 × 104 MPN/g predicted contamination of Salmonella, with a sensitivity of 84% and specificity of 61%. Displaying seafood products on ice, presence of E. coli and Vibrio, and seafood derived from Eastern Thailand were associated with an increased risk of Salmonella contamination.

Prevalence and Antimicrobial Resistance of Bacterial Foodborne Pathogens Isolated from Raw Bivalve Molluscs Subjected to Consumption in Poland during a Ten-Year Period

“…and Vibrio spp. in various kinds of bivalve molluscs was observed by Hariharan and Amadi [ 15 ] and Atwill and Jeamsripong [ 52 ]. The latter authors noticed that the contamination of shellfish with Salmonella spp.…”

“…was significantly associated with the type and source of molluscs, their sampling location, and the presence of E. coli and Vibrio spp. [ 52 ]. In the current study, it was also found that the presence of more than one pathogen was mainly identified in clams and mussels harvested in the Netherlands ( Table 4 ).…”

Calidad microbiológica en muestras de camarón obtenidas en puntos de venta en Tulancingo, Hidalgo

“…es parte natural de los camarones, por lo que su presencia es más probable [16], no obstante en México no está permitido. Otros autores mencionan que la principal causa de contaminación de Salmonella es debida a que está presente en los sistemas acuícolas pero también influye las instalaciones y la prácticas de higiene durante el transporte, almacenamiento y manipulación [18].…”

“…En Tailandia realizaron un estudio en camarones encontrando Salmonella spp. y E. coli en del cual fue 47% y 100% respectivamente [18], referente a E. coli se mostró el mismo comportamiento que en este estudio. También menciona que para este microorganismo el hielo es un factor de riesgo debido a que está contaminado lo que es considerado como un vehículo ya que el hielo al derretirse puede propagar las bacterias [18].…”

“…y E. coli en del cual fue 47% y 100% respectivamente [18], referente a E. coli se mostró el mismo comportamiento que en este estudio. También menciona que para este microorganismo el hielo es un factor de riesgo debido a que está contaminado lo que es considerado como un vehículo ya que el hielo al derretirse puede propagar las bacterias [18]. En México en el acuerdo por el que se da a conocer el Plan de Manejo Pesquero de camarón siete barbas en las costas de los estados de Campeche y Tabasco [19].…”