Neil D Encinares Technology Outreach Station for Marine Water Bureau of Fisheries and Aquatic Resources- Region Impact of Aeromonas hydrophila Infection on Freshwater Aquaculture Center Selected Tilapia (Oreochromis niloticus, FaST Strain (original) (raw)
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2018
A study was initiated to evaluate the performance and hematological responses of Nile Tilapia FaST Strain Oreochromis niloticus (L) to an experimental infection with Aeromonas hydrophila. The experiment consisted of two treatments with three replicates: Treatment 1 (Control)/non-injected fish (NI); Treatment 2 (Infected)/fish injected with Aeromonas hydrophila. Twenty-four hours after injection, the fish were anesthetized and the blood was collected. The hematological test included white blood cell (WBC) counts in treatments. Fish injected with Aeromonas hydrophila showed significant difference in white blood cell (WBC) counts than the non-injected treatment. Final weight and weight gain increased significantly in fish injected when compared to non-injected control. Statistical analysis of survival rate showed significant difference between treatments (P<0.05). Treatment 1 (Control) has significantly higher survival rate which was 75% compared to Treatment 2 (Infected) which was ...
Aeromonas Spp. Infection in Farmed Nile Tilapia, Oreochromis Niloticus
HAL (Le Centre pour la Communication Scientifique Directe), 2021
Nile tilapia is one of the major formed fish species worldwide. However, pathogenic bacteria such as Aeromonas spp. cause a high economic losses. Therefore, the present study was aimed at isolating and investigating the effects of Aeromonas spp on Nile tilapia and evaluating its pathogenicity change after experimental infection. For this purpose, naturally infected Nile tilapia collected form the Ambo University experimental fishpond were transported to the biology laboratory using aseptic plastic bags. Aeromonas spp. isolation and identification were made using morphological and biochemical characterizations. The pathogenicity test was carried out for Aeromonas spp using an intra-peritoneum injection along the caudal peduncle of the fish. Finally, sensitivity test of the isolate was performed using different antibiotics. The results showed that after 24 hours of artificial injections, all the fish decreased their feeding rate and exhibited erratic swimming behaviour. The fish also remained at the bottom and became darkened on their dorsal body part. The fish also showed high hyperaemia on the base of the fins, fin rot and erosion, Internally, they showed pale gills, high intestinal fluid accumulation, pale gonads, pale liver and enlarged gall bladder. The fish also showed an increased of white blood cells as they may migration from the spleen to the blood circulation system. The results also showed that the Aeromonas isolate was highly sensitive to erythromycin and tetracycline. In conclusion, the Aeromonas isolate exhibited a serious effects on external and internal organs of Nile tilapia reared under pond culture system. Additionally, the isolate might affect the immune system of the fish by influencing the nature of blood cells. As control mechanism of the isolate, erythromycin, and tetracycline were more effective and thus these antibiotics can be used for treating the isolate by mixing with fish feed. However, as antibiotics have cumulative effect, it is important to find an alternative controlling methods such as plant based antibiotics and improve production management of the aquaculture systems.
Proceedings of International Seminar on Livestock Production and Veterinary Technology
This study was conducted to evaluate the ability of motile Aeromonas species (MAS) to induce clinical symptoms and some pathological changes in juvenile red hybrid tilapia. A standard dose of infection was selected based on predetermined LD 50. Infected fish were observed for any clinical sign and symptom for 96 hours. Samples of liver, spleen and kidney were collected for histopatological changes due to Aeromonas hydrophila infection. Clinical signs of fish included abnormal swimming behaviour and loss of balance. Most of infected fish suffered from haemorrhagic eyes and lesions on the body surface. Some of the them also developed bilateral exophthalmia. Histopathological changes were observed in kidney, liver and spleen. The infected liver showed severe congestion of hepatic veins and vacuoles formation while anterior kidney manifested degeneration of excretory tubules and glomeruli followed by severe haemorrhages and hyaline droplets degeneration. Spleen on the other hand showed tissues degeneration and vacuoles formation. All targated tissues also showed deposition of haemosiderin pigments followed by proliferation of melanomacrphage centres. Development of such symptoms was associated with the infection with Aeromonas hydrophila. The current study has shown that MAS could serve as the primary cause of severe infection not only in red hybrid tilapia but may also infected other freshwater fish species.The results of histological analysis of various tissues indicates a direct correlation between disease infection and histopathological disorders observed in the tissues.
Egyptian Journal of Aquatic Biology and Fisheries, 2002
T he prevalence of Aeromonas hydrophila infection, the causative agent of motile Aeromonas septicemia, was 47.3% among the diseased cultured tilapias. Oreochromis niloticus was the more sensitive species to MAS. MAS infected tilapia showed loss of balance, reduced growth, fins and tail rot, ulcer and enlargement of the abdomen. Internally, the organs were congested. The intraperitoneal route was more pathogenic than intramuscular one in the experimentally infected 0. niloticus. Microscopically different organs showed histopathological changes. Also, changes in serum biochemical parameters were recorded. The antibacterial activity of Oxytetracyclin (OTC) was evaluated both invitro and in vivo. OTC was the drug of choice for the control and prevention of MAS under laboratory and field conditions. Immunization of tilapia with formalin-killed whole culture vaccine through intraperitoneal route gave successful results.
Emergent Life Sciences Research
Aeromonas hydrophila is a Gram-negative bacterium present in the water, which can cause disease in animals, such as fish, frog, and mammals, including humans. In fish, Aeromonosis occurs when it is immunosuppressed due to the stress of handling, water quality, parasitism or population density. Due the importance of this disease in fish and humans, this study aimed to detect this bacterium by PCR in Nile tilapia (Oreochromis niloticus) of cage fish farms localized in hydro-electrical reservoirs of São Paulo state, Brazil and describe the lesions found in positive fish by necropsy and histopathology. Around 360 samples of Oreochromis niloticus specimens were randomly sampled at six Brazilian fish farms in November 2014 (n = 180) and in March 2015 (n = 180). The identification of A. hydrophila by PCR showed the prevalence since 3.33% to 46.66%. The most common macroscopic lesions were hemorrhage and splenomegaly, and bacteria colonies, coagulative necrosis, hemorrhage, inflammatory process, melano-macrophages, and vacuolar degeneration were microscopic. The pathological and histopathological findings showed the presence of an infectious disease, and employing the molecular technique, it was possible to identify that the analyzed fishes had A. hydrophila. Thus, producers should utilize this information using histopathology and molecular techniques in tilapia to reduce economic losses and avoid disease in consumers.
Aeromonas Septicemia Infection in Cultured Nile tilapia, Oreochromis niloticus L
2021
The study was conducted at Gudar Experimental Aquaculture farm, from November 2011 to March 2012. The main objectives of the present study were to investigate host-parasite relationship of Aeromonas bacteria in Nile tilapia (Oreochromis. niloticus) in aquaculture production system and evaluate pathogenicity and hematological change through experimental infection. The bacterial isolates were identified according to the biochemical reactions scheme. The pathogenicity test was performed for Aeromonas bacteria through intra-peritonium injection (IP) using 21/gauge sterile needle at ventral parts of the body of experimental fish. After 24 hours post injection of bacteria (1.4 x 106 CFU ml-1), all fish fingerlings became less active, showed decreased feeding rate and erratic swimming behavior, and remained at the bottom of the aquarium. External clinical signs observed were darkened dorsal part of body and mild hyperemia of the pectoral and ventral fin bases. Significant hyperemia on the ...
Biology, 2021
The genus Aeromonas has been recognised as an important pathogenic species in aquaculture that causes motile Aeromonas septicaemia (MAS) or less severe, chronic infections. This study compares the pathogenicity of the different Aeromonas spp. that were previously isolated from freshwater fish with signs of MAS. A total of 124 isolates of Aeromonas spp. were initially screened for the ability to grow on M9 agar with myo-inositol as a sole carbon source, which is a discriminatory phenotype for the hypervirulent A. hydrophila (vAh) pathotype. Subsequently, LD50 of six selected Aeromonas spp. were determined by intraperitoneal injection of bacterial suspension containing 103, 105, and 107 CFU/mL of the respective Aeromonas sp. to red hybrid tilapias. The kidneys, livers and spleens of infected moribund fish were examined for histopathological changes. The screening revealed that only A. dhakensis 1P11S3 was able to grow using myo-inositol as a sole carbon source, and no vAh strains were...
Veterinary World, 2020
Background and Aim: Aeromonas hydrophila is a major cause of bacterial infections affecting a wide range of warm water fishes worldwide. In Malaysia, A. hydrophila isolations from diseased fishes were previously reported; however, with limited information. The present study investigates the antibiotic susceptibility and pathogenicity of A. hydrophila isolated from farmed red hybrid tilapia (Oreochromis spp.) in Malaysia. Materials and Methods: A. hydrophila was biochemically identified and subjected to antibiotic susceptibility tests. The isolate was then intraperitoneally injected into red hybrid tilapia, and the mortality, clinicopathological changes, and LD50 were determined up to 240 h post-infection (hpi). Results: The isolate demonstrated multiple antibiotic resistances (MAR) toward amikacin, ampicillin, cefotaxime, amoxicillin, trimethoprim-sulfamethoxazole, erythromycin, and streptomycin, with a MAR index of 0.5. The experimental infection of A. hydrophila at 105 CFU/mL in the red hybrid tilapia resulted in 100% mortality at 240 hpi. The LD50 was determined at 1.1×104 CFU/mL. Infected fish demonstrated occasional erratic swimming patterns, localized hemorrhages and depigmentation on the body and operculum areas, fin erosion, enlargement of the gall bladder, and hemorrhage in internal organs. Microscopic observation of infected fish revealed brain congestion, tubular necrosis, and glomerular shrinkage in the kidneys, necrosis of hepatocytes, and congestion of blood vessels in the liver. Conclusion: The high virulence of A. hydrophila to the red hybrid tilapia emphasizes the importance of active, on-going monitoring of its prevalence in Malaysian tilapia farming.