A Prevalence Study of Histamine and Histamine Producing Bacteria in Two Commercial Tropical Marine Fish Sold in Trinidad, West Indies

Background: Scombroid poisoning is responsible for the highest morbidity worldwide of any fish related food poisoning. However, there is little information available on this potential hazard to the fish consuming population of the Caribbean. This study focused on quantifying the levels of scombroid toxin (histamine) and selected histamine producing bacteria in two popularly consumed marine fish (carite, Scomberomorus brasiliensis and king fish, Scomberomorus cavalla ) in Trinidad, West Indies. Methods: A total of 78 fish were sampled at five different market types throughout the island. A commercial histamine kit was used to quantify histamine levels and the overall microbiological quality was evaluated from aerobic plate counts of fish tissue. Secondly, the role of fish and market types was investigated as potential sources of histamine producing bacteria (HPB). Results and conclusion: Of the fish sampled, 98.7% had histamine levels within USFDA acceptable limits of ≤ 50ppm. Overall, histamine levels were significantly higher in carite than in kingfish. One carite sampled from a wholesale market was in violation of the limit with a histamine level of 57 ppm. A significant relationship was observed between sensory characteristics and histamine levels. Fish tissue and gills were the main sources of histamine producing bacteria. There was a significant (p = 0.05) association between market type and the number of histamine producing bacterial types, with the highest morphological diversity of HPB present in fish from landing sites and retail markets. These market types also had the highest proportion of bacterial isolates positive for potential histamine production (12.9% each) as compared to supermarkets (11.3%), wholesale markets (8.1%) and mongers (6.5%).