Study finds E. coli, Listeria and Vibrio in seafood

Researchers have looked at the presence of certain foodborne pathogens in seafood collected in Turkey.

The study examined levels of coliform bacteria, E. coli, Listeria monocytogenes, Vibrio vulnificus, and Vibrio cholerae in 700 samples of raw sea fish, raw mussels, raw shrimp, and raw squid.

Nearly half of seafood products analyzed were contaminated with coliform bacteria. Almost one in five, or 131 of 700 samples, were contaminated with E. coli, 60 with Listeria monocytogenes, and 24 with Vibrio vulnificus. Vibrio cholerae was not found.

Microbiological quality of seafood can vary depending on environmental conditions, quality of water, water temperature, salinity, distance to residential areas and pollution, natural bacterial flora in water, food consumed by fish, fishing methods, and cooling conditions.

Since seafood and fish are susceptible to secondary contamination, the purchasing stage, treatments during the preparation process, and consumers’ compliance with hygiene rules are important for food safety.

E. coli and Listeria results
All samples were collected in Istanbul, Turkey, from fish wholesale markets, fish markets, fish hawkers, and bazaars. This included 400 samples of raw fish such as gilt-head sea bream, sea bass, bluefish and horse mackerel, and 100 from the other types, according to the study published in the journal Foodborne Pathogens and Disease.

The number of positive samples for coliform bacteria for raw fish, raw mussels, raw shrimp, and raw squid were 210, 47, 41, and 39 respectively.

E. coli was detected in 67 raw fish samples, 21 raw mussels, 24 raw shrimp and 19 raw squid samples. Listeria monocytogenes was found in 29 samples of raw fish, 16 of raw mussels, 11 of raw shrimp, and four of raw squid.

Studies on the presence of Listeria monocytogenes in seafood are limited. Researchers said their results show it is a serious risk in such products. In particular, the lack of understanding of the epidemiology in seafood is considered to increase the risk for consumer health.

Vibrio risk
The number of positive samples for Vibrio vulnificus for raw fish, raw mussels, raw shrimp, and raw squid were 11, nine, four, and zero, respectively.

“When the pathogenicity of Vibrio vulnificus and possible infection results are taken into account, raw mussels sold uncontrolled by fish hawkers are very serious risk factors for public health. Another important danger related to Vibrio vulnificus is that it does not cause appearance, odor, and taste disturbances in seafood, such as fish, oysters, and mussels from which the agent is isolated,” said researchers.

Further studies are needed to reveal the detailed behaviors of seafood pathogens, manner of contamination, epidemiology, and genetic structures of contaminants to maximize consumer health.

To create public awareness, training of seafood employees at every stage of production is believed to be important to decrease the incidence of pathogens threatening public health. Effectiveness of government agencies in the seafood supply chain is also important, according to the report.

Total quality management and good hygiene practices should be applied at all points that sell ready-to-eat food and should be controlled at the ministerial level to minimize the risk of microbes and parasites to protect consumer health, said researchers.

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