RESUMO
Anomalocardia brasiliana is an intertidal filter-feeding clam that can accumulate enterobacteria, such as Escherichia coli, and consequently affect human health. Shellfish depuration is a procedure which reduces microbiological contaminants; however, salinity and depuration time can vary across species to adequately reduce bacteria load. To analyze the effect of salinity on the bioaccumulation and depuration of E. coli by A. brasiliana, this study evaluated salinity and depuration time in animals artificially contaminated with E. coli. Each experimental group of clams were acclimated for 6 hours in a recirculating aquaculture system (RAS) and then exposed to E. coli for 18 hours. Following exposure, clams were then held at one of four salinities (35, 30, 25 e 20) for a period of one of four depuration times (0, 12, 24, 36 and 48h). The highest bioaccumulation of E. coli in A. brasiliana was observed in clams held at salinities of 35, 30 and 25. The greatest reduction of E. coli in A. brasiliana was observed in clams held at 25 for 48 hours. A salinity of 20 showed low bioaccumulation and depuration of E. coli. The results of this study will contribute to developing a protocol for depurating A. brasiliana to mitigate human health concerns.
Anomalocardia brasiliana é um molusco de areia filtrador que habita entremarés, o qual pode acumular enterobactérias como E. coli e, consequentemente, afetar o ser humano. A depuração de moluscos é o procedimento para reduzir a contaminação; para isso, é necessária uma adequada qualidade da água. A fim de analisar o efeito da salinidade na bioacumulação e na depuração de E. coli por A. brasiliana, o presente estudo avaliou quatro salinidades (35, 30, 25 e 20) e quatro tempos de depuração (0, 12, 24, 36 e 48h) em animais contaminados artificialmente com E. coli. Todos os moluscos foram aclimatados por seis horas e posteriormente expostos a E. coli por 18h no sistema de depuração. O experimento de depuração foi realizado em um sistema de recirculação de água (RAS). A maior bioacumulação de E. coli em A. brasiliana foi observada nas salinidades de 35, 30 e 25, e a maior redução de E. coli nos animais foi observada na salinidade de 25, após 48h de depuração. A salinidade de 20 apresentou uma baixa bioacumulação de E. coli. A maior redução de E. coli em A. brasiliana foi observada na salinidade 25 depois de 48h de depuração. Os resultados do presente estudo podem contribuir para o desenvolvimento de um protocolo de depuração para essa espécie.
Assuntos
Animais , Escherichia coli/isolamento & purificação , Cardiidae/microbiologia , Bioacumulação , Taxa de Depuração Metabólica , SalinidadeRESUMO
The bacterial species, Vibrio parahaemolyticus and Vibrio vulnificus, are ubiquitous in estuaries and coastal waters throughout the world, but they also happen to be important human pathogens. They are concentrated by filter-feeding shellfish which are often consumed raw or undercooked, providing an important potential route of entry for an infective dose of these bacteria. Vibrio parahaemolyticus can cause abdominal cramping, nausea, diarrhoea, vomiting, chills and fever. Vibrio vulnificus can cause similar gastrointestinal-related symptoms, but can also spread to the bloodstream, resulting in primary septicaemia, and it can also cause disease via wound infections. The objective of this article is to summarize, for the first time, the incidence and importance of V. parahaemolyticus and V. vulnificus in South America, in environmental waters and seafood, especifically molluscan shellfish, as well as human infection cases and outbreaks. It appears that infections from V. parahaemolyticus have been more strongly related to shellfish ingestion and have been more frequently reported on the Pacific coast of South America. Conversely, V. vulnificus has been more frequently acquired by water contact with open wounds and its presence has been more heavily reported along the Atlantic coast of South America, and while documented to cause serious mortality, have been relatively few in number. The impacts of El Nino Southern Oscillation (ENSO) have been observed to cause an increase in V. parahaemolyticus outbreaks on the Pacific coast of South America. The implementation of a regulated monitoring approach, along with the use of faster, more accurate and virulence-specific detection approaches, such as PCR confirmation, should be considered to detect the presence of pathogenic Vibrio strains in environmental and seafood samples for protection of public health. Furthermore, improved clinical surveillance with suspected cases should be implemented. This review highlights the need for more research and monitoring of vibrios in South America, in water, shellfish and clinical samples.