ABSTRACT
Resistance bacteria may be transferred to humans through the consumption of fishes and shellfishes. Hence, this study characterised E. coli isolates from fishes and shellfishes in Creek Road/Bonny Estuary, with the use of molecular techniques. Seventy two (72) fishes and shellfishes were examined for the presence of E. coli. Most probable number (MPN) technique, Eijkman test and molecular techniques were used for the isolation and identification of E. coli. The analysis was performed seasonally, which was during the end of rainy season (November), start of rainy season (April) and middle of rainy season (July). Eleven (11) isolates of E. coli (randomly selected) recovered from the fishes and shellfishes were screened for resistance genes in the pathgotypes of E. coli (EHEC, EPEC, EAEC, ETEC and EIEC, including SHV, CTX-M, TEM and MCR genes. The results showed that both coliforms and E. coli were recovered from the fishes and shellfishes. The distribution of the resistance genes in the E. coli isolates from fishes and shellfishes is: fishes – SHV (9.5%); CTX-M (11.1%); TEM (7.9%); MCR (0%); str1 and str2 (6.3%); esV and bfA (3.2%); aaiC (7.9%); elt (6.3%); invE (4.7%) and shellfishes - SHV (5.6%); CTX-M (5.6%); TEM (7.4%); MCR (0%); str1 and str2 (3.7%); esV and bfA (0%); aaiC (0%); elt (0%); invE (3.7%). In fishes and shellfishes, the most detected of all the genes are CTX-M and TEM, respectively. The data from this study suggest that fishes and shellfishes can be reservoirs of antibiotic resistance genes. These genes can easily be transmitted to humans through the consumption of raw or improperly cooked fishes and shellfishes, creating public health problem.
ABSTRACT
Aims: To evaluate the proximate composition and mineral contents of edible part of four species of shellfishes (Callinectes amnicola, Thais coronata, Tympanotonus fuscatus and Egeria radiata) from the Calabar River, Nigeria. Place and Duration of Study: Institute of Oceanography, University of Calabar, Nigeria, between October 2016 and May 2017. Methodology: The proximate composition was analyzed following standard methods recommended by AOAC, while mineral contents were determined using Atomic Absorption Spectrophotometric (AAS) method. Results: Protein and ash contents were highest in E. radiata (32.10 ± 0.06% and 3.80 ± 0.01%) and least in T. coronata (14.88 ± 0.01% and 2.57 ± 0.02%). Fat, fibre and moisture contents were highest in T. coronata (1.50 ± 0.01%, 0.06 ± 0.01% and 76.35 ±0.01%) and least in T. fuscatus (1.18 ± 0.01%), E. radiata (0.04 ± 0.01% and 61.20 ± 0.11%). Nitrogen-free extract was highest in C. amnicola (6.42 ± 0.25%) and least in E. radiata (1.50 ± 0.10%). Sodium content was highest in C. amnicola (108.34 ± 0.08 mg/100 g) and least in T. fuscatus (16.33 ± 0.01 mg/100 g). Calcium content was highest in T. coronata (188.42 ± 0.09 mg/100 g) and least in T. fuscatus (49.86 ± 0.01 mg/100 g). Copper, iron and manganese contents were highest in T.coronata (10.03 ± 0.02 mg/100 g, 14.83 ± 0.01 mg/100 g and 1.65 ± 0.01 mg/100 g) and least in C. amnicola (0.49 ± 0.01 mg/100 g), E. radiata (8.76 ± 0.01 mg/100 g) and T. fuscatus (0.21 ± 0.01 mg/100 g). All proximate composition and mineral contents except fibre content were significantly different (P < 0.05) among the four species. Conclusion: The nutritional values of the four species of shellfishes studied are suitable for human consumption, and the species could have potential alternative for animal feed industries. Therefore, aquaculture activities related to shellfishes should be encouraged to reduce pressure and total dependence on wild stock.
ABSTRACT
In view of the present situation that edible marine shellfishes are combinedly contaminated by different kinds of lipophilic toxins, common lipophilic shellfish toxins in marine shellfishes were simultaneously detected by liquid chromatography-tandem mass spectrometry, and the safety risk of commercial marine shellfish was evaluated using the risk assessment method based on combined contamination of various toxins. Under the optimum conditions, satisfactory recoveries (63. 3％ - 88. 8％ ), precision ( relative standard deviations RSD≤14. 5％ ) and sensitivity (limit of detection in the range of 0. 5-2. 7 ng / g) of the method were achieved for all the analytes. Among the 105 commercially available shellfish samples, 42. 86％ of the samples had at least a kind of toxin. The highest average content was 47. 6 μg / kg of DTX1, which was the most serious contaminant for marine shellfishes. The total Expose Risk Index (∑ERI) was calculated based on Tolerable Daily Intake (TDI) and Acute Reference Dose (ARfD) of each toxin to evaluate the safety risk of commercial marine shellfish. The results showed that the ratio of commercially available marine shellfish with safety risk was 19. 05％ and the food safety risk of scallop was the highest. In summary, a new method based on the combined contamination of lipophilic shellfish toxins was successfully developed for risk assessment of the commercial marine shellfish. The proposed method is more harsh compared with the European Food Safety Authority (EFSA) regulation and can make shellfish consumers better to avoid the risk of poisoning.
ABSTRACT
This study was conducted to examine the levels of total and organic mercury in the scalp hair of the elementary school children and adults, and their relalionship with the consumption pattern of fishes and shellfishes. The scalp hair samples were collected from the occipital part of 115 children and 131 adults in costal, urban and rural areas of kyungpook province from June to August 1991. The mercury content was analysed by the atomic absorption spectrophotometer (model IL. 555)with atomic vapor accessory (model IL. 440). The total and organic mercury contents of hair were significantly higher (P<0.01) among the children who prefer fish and/or shellfish (7.728ppm, 6.610ppm), and canned fish and/or fish pastes (6.969 ppm, 5.885ppm) than those who prefer meat(4.822ppm, 3.905ppm) and vegetables(3.974ppm, 3.224 ppm). The children who prefer to eat the canned fish without cooking showed a higher mercury content than the children who prefer to eat it as stew or mixed with vegetables (P<0.01l). There was a dose-response relationship between the intake frequency of canned fish, raw fish and cooked fish and the content of total and organic mercury of hair; the children who eat fish almost everyday showed 2 times higher than those who eat rarely (P<0.0l). The mercury content in the hair of the children who eat raw fish was significantly higher than that of the children who eat boiled or broiled fish (P<0.01). The total and organic mercury contents of adult scalp hair increased with age up to the forties and slightly decreased in the fifties. The mercury contents of those who were engaged in the fishery and raw fish restaurant were 2 times higher than those of the farmers. The mercury content of the persons who were favorite dishes of fish and shellfish were most high, and who prefer raw fish were 2 times higher than those of the persons who prefer vegetables and broiled fish. The contents of total and organic mercury in adult scalp hair showed also a increasing tendency with the intake frequency of raw and cooked fish.