Pseudomonas aeruginosa (P. aeruginosa) is a psychotropic pathogenic bacterium that is considered one of the most common spoilage microorganisms related to seafood’s consumption. P. aeruginosa is widely distributed in nature and isolated from soil, plants, animals, and water. Because of its high resistance to a wide range of antibiotics, P. aeruginosa is more dangerous than other spoilage bacteria. It possesses a diverse set of virulence factors capable of causing severe and aggressive infections in humans and animals. Antibiotic resistance genes are easily transmitted to humans via contaminated seafood, resulting in a serious antibiotic resistance.  The ability of P. aeruginosa to form a biofilm maintains its environmental survival and allows its quick adaptation to harsh environments. Therefore, for the benefit of customers and public health globally, the safety and bacteriological quality of commercially processed fish and its products are crucial.

Fish and fish products represent major contributors to supply humans with part of their needs of the essential amino acids, vitamins, minerals, omega -3-fatty acids, and other needed micronutrients. However, fish and fish products are highly perishable foods that can easily spoiled and decomposed, possibly because of its cross contamination from the surrounding environment. Fish attracts a vast array of microorganisms, of these; mould and yeast represent a major sector of these microbiota, which by turn van lead to rapid decomposition of fish or even produce several toxicological implications if ingested. In this review, we will highlight the available literature about mould contamination of fish and fish products with a special reference to its public health significance.

Vibrio species are major sea foodborne pathogens that cause gastroenteritis as a serious disease of human public health due to the consumption of undercooked or raw fish. In the current study, a total of 100 fish samples (Nile tilapia, Nile perch, Meagre, and Sea bass) were collected randomly from retail markets in Egypt to investigate the prevalence of Vibrio species. The results revealed that Vibrio species isolated with an overall percentage of 52% of all examined fish. Bacteriological and chemical examinations revealed 42.3% V. parahaemolyticus, 26.92% V. mimicus, 19.23% V. alginolyticus, 9.62% V. vulnificus and 1.92%V. cholera. Antibiotic sensitivity declared high resistance of the isolates to different antimicrobial agents used in Egypt including Ampicillin (100%), Nalidixic acid (88.3%), Streptomycin (84.2%), Sulphamethoxazol (70.7%) and Oxytetracycline (64.8%) and it had sensitivity to Amikacin (94%), Ciprofloxacin (70.5%), Gentamicin (58.9%) with an average MAR index of 0.576. By polymerase chain reaction, all examined Vibrio isolates were positive for 16SrRNA specific for Vibrio spp. and harbored toxR gene virulence gene.  Finally, dipping of tilapia in lemon juice 5% for 2 h reduced V. parahaemolyticus count by 0.42log cfu/g (62.08%). Consequently, hygienic measures should be approved to control the contamination of fish in the markets and the aquatic environment. Regular monitoring of fish for antibiotic resistance by Vibrio species, and their molecular characterization is necessary to improve the safety of seafood. Dipping fish in lemon juice is an efficient strategy for reducing V. parahaemolyticus load in fish.

This study describes the macroscopic and microscopic lesions in farmed rainbow trout (Oncorhynchus mykiss) naturally infected with genetically identified Aeromonas salmonicida, A. hydrophila, and A. veronii species. The genus Aeromonas includes bacteria that naturally inhabit both waterways and organisms. At least 27 Aeromonas species have been identified to date, some of which can cause significant economic losses in aquaculture. As up to 68.8% of Aeromonas isolates may be misidentified in routine biochemical and phenotypic tests, however, reported cases of Aeromonas infection in fish may be wrongly identified. Our findings confirmed that the 3 Aeromonas species studied are associated with septicemia and dermal lesions in rainbow trout.

The pirarucu, Arapaima gigas (body weight = 18.3 kg and total length = 102 cm) which had been reared in one of the private commercial aquaria for exhibition was found dead and submitted for diagnostic examination. A pure bacterial culture was isolated from the kidney, which was enlarged, and contained fluids. Results of the bacterial identification yielded Serratia fonticola. This paper describes the first isolation of S. fonticola from pirarucu.

Objective: To validate the use of radiography to determine the length of sagittal otoliths in intact bogue (Boops boops; a sparid fish [commonly called sea bream]). Sample: 52 bogue cadavers. Procedures: Weight and standard lengths (from the tip of the snout to the caudal end of the last vertebra) of fish were measured. The radiographic beam was centered over the postorbital area, and images were obtained via ventrodorsal, 30° right dorsal–left ventral oblique, and 30° left dorsal–right ventral oblique projections. Otoliths were removed from the fish; sagittae were measured directly and on radiographic images by use of a vernier caliper. The relationship between direct and radiographic measurements of sagittal otoliths was calculated. Results: Paired sagittal, lapillus, and asteriscus otoliths were identified. Sagittal otoliths were comma-shaped on ventrodorsal projections; in oblique projections, they appeared ovoid and pairs of otoliths were located in the same dorsal plane. Radiographic length of sagittal otoliths was significantly correlated with directly measured length, and radiographic measurements were not significantly different between ventrodorsal and oblique radiographic projections. Conclusions and Clinical Relevance: Radiographic examination of sagittae was useful to determine the length of sagittal otoliths and, consequently, the fish length. In ecological applications, the radiographic measurement of sagittal otolith length may be useful for studies on the aquatic diet of organisms (fish, pinnipeds, and marine birds) because it allows for quick back-calculation to the size of prey.

The purpose of the study was to verify the existence and pathogenicity of Aeromonas hydrophila (A. hydrophila) in fish by validating the bactericidal effects of microwave and Gamma radiation on infected fish fillets. A total of 100 frozen Basa fish fillet samples were collected randomly from different markets in Zagazig, Sharkia Governorate, Egypt, and subjected to microbiological examination. The results revealed a 14% prevalence rate of A. hydrophila in fish fillets, which were tested for the presence of seven virulence genes: aerA, act, ast, alt, hyl, ahhR, and ahh1. All isolates exhibited traits related to virulence. The most predominated gene was ast (64.2%), followed by aerA, act, hyl, and ahhR (57.14% for each). Then, an experimental protocol for several treatments showed that Gamma radiation at a dose of 1 kGy decreased the count of A. hydrophila in fish fillets by 4.4 log10 CFU/g whereas doses of 2 and 3 kGy eradicated the pathogen. The same positive effect was recorded towards the microwave after cooking for 1, 2, and 3 minutes. Therefore, using microwave cooking and Gamma-irradiation alone and in combination with other decontamination methods may be more efficient in lowering the pathogen counts in fish meat.

In the aquatic environment, pollution with heavy metals is a major issue. Some of them are essential heavy metals because they play biological roles for aquatic organisms. Other heavy metals, however, are regarded as dangerous even at low concentrations. Heavy metal levels that are harmful may be caused by industrial, mining, and agricultural operations. Water contamination and changes to the physicochemical properties of the aquatic environment will result from this. The harmful toxic consequences of this pollution on fish raise questions about its possible impacts on human health. The most prevalent heavy metals are arsenic, cadmium, lead, and mercury, which are systemic toxicants and have an impact on human health. These metals are classified as carcinogens by the United States Environmental Protection Agency and the international agency for research on cancer because they cause organ damage even at low exposure levels. This review was created to contribute to the understanding of the environmental impact, toxicology, and consequences of heavy metals on fish.

Vibrio is a major sea food pathogen which needs to be monitored regularly for devising appropriate control strategy to ensure food safety among sea food consumers and handlers. The present study aims to ascertain the occurrence of Vibrio spp. in seafood viz fishes, prawn/shrimps, crabs and water samples collected from various fish markets in and around Chennai city, Tamil Nadu, India. A total of 175 samples were screened, of which 106 (60.57%) samples were found positive by PCR targeting the 16s rRNA of Vibrio genus and all the positive isolates were subjected to toxR gene identification by Multiplex PCR for species level identification. At the species level 28(26.41%) were positive for Vibrio parahemolyticus (Vp), 6 (5.67%) positive for Vibrio Cholerae (Vc), 2 (1.89%) positive for Vibrio vulnificus (Vv). The presence of mixed vibrio species were also observed of which 56 samples (43.40%) revealed the presence of Vp and Vc, 7 (6.60%) with Vp and Vv, 3 (2.84%) with Vv and Vc and 14 samples with (13.20%) Vp, Vv and Vv. The present study identified the presence along with mixed Vibrio spp. in most of the samples tested from the study area.

Objective: Rodlet cells produce secretions of glycoproteins in nature. This study investigated the microscopic morphology, histochemical and immunohistochemical reactions, and distribution of the rodlet cells in the gut of Binni fish (Mesopotamichthys sharpeyi). Materials and Methods: Thirty samples were obtained from the cranial, middle, and caudal por¬tions of Binni intestine immediately after being euthanized, fixed in Bouin's solution for 18 h at 24°C, and had undergone routine histological processing, different conventional histochemical stains, and immunostaining with TNF-α and S100 protein antibody. Results: The intestine of Binni fish showed different stages of rodlet cells classified into three distinctive forms: vesicular, granular, and mature cells. Rodlet cells are poorly stained with hema¬toxylin and eosin. Their secretory granules have a weak positive reaction with periodic acid-Schiff (PAS) and Alcian blue (AB), and react positively to combined AB and PAS. Rodlet cells were stained lightly with Safranin O, observed pink in color by Giemsa stain, and showed reactivity to Masson's and Mallory trichrome stains. Rodlet cells were immunostained positively against TNF-α and S100 antibodies, indicating that they have an immune function. Conclusions: Rodlet cells, with their neutral glycoprotein secretions, play a crucial role in the immunity of Binni fish intestine. [J Adv Vet Anim Res 2022; 9(2.000): 282-289]