This study examined the nature and level of foodborne pathogens and spoilage bacteria in Carite (Scomberomorus brasiliensis) available to consumers in various market types in Trinidad, West Indies. Chilled and frozen samples (52) were collected between the months of January and June 2014. Popular purchasing venues include from supermarkets (30), wholesale markets, retail outlets, roadside fish vendors and landing sites. Total aerobes were enumerated using standard plate count methods. Samples were also plated on selective media: MacConkey, Eosin Methylene Blue, Aeromonas (Ryan Medium) and Baird Parker. Colonies were selected, purified and biochemically pre-screened before final identification using API20E. Carite purchased from supermarkets, wholesale markets, retail outlets, fish vendors and landing sites had mean aerobic counts of (Log CFU g-1) 5.31±2.11, 4.43±0.49, 4.53±0.54, 3.06±0.05 and 2.96±0.40 respectively. Bacterial types with the highest overall prevalence rates include Staphylococcus aureus (15.4 %), Escherichia coli (7.7 %), Proteus mirabilis (9.6 %), and Rauttella planticola (7.7 %).

Keywords: carite, food safety, prevalence, pathogen, Trinidad, foodborne diseases

Consumption patterns are changing as persons are more knowledgeable of what they eat and healthier eating habits are becoming more and more established. This change has seen a greater demand for food items such as fish and fish products; primarily due to the fact that fish is high in protein and other essential nutrients. The fish industry globally accounted for the livelihood of some 54.8 million persons¹ and is the largest growing subsector in agriculture valued at USD 217.5 billion. The global per capita consumption of fish has increased from 5.6 kgs in 1960 to 17.1 kgs in 2009.² With this increase in consumption and consumer knowledge food safety issues are being highlighted more and more in the media with fish being no exception.

Fish has been implicated as one of the main food categories in which outbreaks of foodborne illness has been reported.³ In 1998-2008; 3264 cases of foodborne illness was reported in the United States 17% of which was related to fish consumption. It is estimated that one third of the population of the United States acquire foodborne diseases annually. Schlosser indicated that estimates of foodborne diseases are responsible for the approximately 200000 persons becoming ill, 900 of which would be hospitalised and 14 which may die. During a 7 week period in 2012, The Caribbean Public Health Agency formerly the Caribbean Epidemiology Centre reported 94 cases of foodborne and water borne diseases from its member countries. Surujlal and Badrie reported that there were some 2597 cases of foodborne illness reported in 2000 and 1905 in 2001.

The Caribbean region, and more specifically Trinidad the fish industry estimated value Trinidad and Tobago Dollars (TTD) 94.5 Million in 2009 and increase of 6.4% from 2008 data. One of the more popular fish species consumed in Trinidad is Carite. This species accounted for a landing of 1800 metric tons between 1996 and 2006. However, little published information on pathogens associated with this species of fish can be found. Therefore, the objective of this study was to determine the prevalence of various foodborne pathogens and spoilage organisms found in Carite, obtained from different market types in Trinidad.

Supermarkets (30), wholesale markets (4), retail outlets (24), landing sites (12) and fish vendors (32) were sampled, between the months of January- June. All market types were sampled once. Samples (chilled and frozen) were immediately packed on ice after purchase, and transported in an insulated ice box to the Food Microbiology Laboratory, Faculty of Engineering, UWI, St. Augustine, Trinidad for analysis. Chilled fish samples were processed on the same day of collection, and frozen samples within 24 hours of collection after thawing overnight under refrigerated temperatures (4˚C).

Samples were analysed according to a method by Kim et al.⁴ In short, 25 grams of combined muscle and skin were aseptically diluted with 0.1% peptone water and plated on 0.5% salted plate count agar. Frozen and chilled samples were incubated at 25˚C/3 days and 15˚C/5 days respectively. Samples were also spread plated on Aeromonas, MacConkey, Baird Parker and Eosin Methylene blue agar media. After incubation at 35˚C/24 hours, 15 representative colonies from each medium were, purified on plate count agar and subjected to the following tests: Gram stain, lactose fermentation, indole, methyl red-Voges Proskauer, lysine decarboxylase, urease, citrate, production of hydrogen sulphide, and motility. Final identification was done using API20E (Biomerieux).

Statistical analysis was conducted using SPSS version 17.

There is an increased demand for fish during the Easter/Lenten season in Trinidad when this study was conducted, that may have accounted for the relatively small number of samples collected from the outlets. Percentage collection was lowest in retail and fish vendors (12.5% each) and highest for wholesale market (100%). Supermarkets had as many as three brands which accounts for the high sample collection.

Microbial counts increased with handling along the food supply chain.⁵ This observation is supported in this study, where supermarkets had the highest microbial counts (5.3 ± 2.11 Log CFU/g) and landing sites had the lowest counts (2.96 ± 0.40 Log CFU/g) (Table 1). Chilled samples were collected from the outlets that held the products at temperatures of 1˚C-10˚C, outside the recommended range of 1- 4.4˚C for fish products.² Supermarkets maintained temperatures ranging from 1˚C to 5˚C, but fish vendors and landing sites kept their fish on ice with temperatures ranging from 5˚C to 10˚C. The landing sites had fresh catch that was sold wholesale to retailers.

The relatively high microbial counts of the vendors and landing sites may be due to their inadequate holding temperatures. However, fish at landing sites were held for shorter periods which probably accounted for their lower counts. The higher counts in supermarket may be due to loss of control during handling, processing and storage. Frozen samples were collected from the supermarket outlets that kept the products within acceptable temperatures <-18˚C. However, there were quality variations that may have been influenced by variations in storage conditions, packaging, and length of time held, as evidence by the observation of freezer burn and stuck pieces of fish. This phenomenon may have accounted for the relatively high counts in these samples.

Foodborne pathogen associated with fish can be categorized into three broad groups: (1) indigenous bacteria belonging to the natural microflora of fish (Clostridium botulinum, pathogenic Vibrio spp., Aeromonas hydrophilia); (2) enteric bacteria present due to fecal contamination (Salmonella spp., Shigella spp.,pathogenic Escherichia coli, Staphylococcus aureus) and (3) bacterial contamination during processing, storage or preparation for consumption (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Clostridium perfrengenes and Salmonella spp.).^6,7

Microbial population of Chilled samples showed that Staphylococcus aureus was seen in all market types with the highest prevalence in fish vendors. Vibrio fluvlialis and Proteus mirabilis were seen in 66.7 % of market types. Landing sites had the greatest microbial diversity, followed by supermarkets. The most isolated bacterial type were pathogens, which could be due handling.

Vibro fluvialis is an emerging pathogen commonly found in coastal environs.⁸ V. fluvialis was reported to be responsible for diarrheal outbreaks and sporadic extra- intestinal cases.⁸ Additionally, the characterization of the an enterogenic El Tor like heamolysin in V. fluvialis which represents one of the virulence factors in V.cholera makes this bacterium one of public health interest.⁹

The bacteria found in frozen samples were Staphylococcus aureus, Escherichia coli and Enterobacter cloacae- were seen in all market types. Escherichia coli had the highest prevalence of all isolated bacteria, when looking at market type. Supermarkets had the largest variation of organisms followed by wholesale market. Spoilage organisms were the most isolated when looking at the variations within organisms’ type. Pseudomonas oryzihabitians, Serratia liquefaciens, Pseudomonas luteola and Rauttella planticola were isolated in 66.7% of market types.

Fifteen (15) microorganisms were isolated from 52 samples, with Staphylococcus aureus being the most prevalent. The isolation of pathogenic bacteria namely Staphylococcus aureus, Escherichia coliand emerging foodborne pathogens such as Vibrio fluvlialis, reveal that there is a risk to public health. Market type influenced aerobic counts, with supermarkets having statistically higher counts. High bacterial counts strongly suggest the need for improved quality control in retailing Carite in Trinidad.

None.

The author declares no conflict of interest.

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