Acute hepatopancreatic necrosis disease (AHPND) of shrimps is a bacterial disease, first appeared in China in 2009 and causes mortality up to 100 % which usually occurs early (within approximately first 35 days) after stocking shrimp fry of black tiger shrimp, Penaeus monodon (Fabricius) and white leg shrimp, Litopenaeus vannamei (Boone). The purpose of this study was to isolate and identify the pathogenic strain of V. parahaemolyticus causing AHPND in cultured shrimps (P. monodon) using molecular techniques. After a disease outbreak in April 2017, shrimp samples were collected from three different locations of south-west shrimp farming region of Bangladesh viz. Satkhira, Khulna and Bagerhat districts. In this study, three selective media were used for primary isolation of V. parahaemolyticus. Among 28 primary isolates, representative14isolates were checked for the species-specific detection of V. parahaemolyticus using ldh primers and all of them were found to be positive. The isolates were further characterized to check their AHPND positivity using AP3 and AP4 primers. Four isolates showed positive results for both AP3 and AP4 which indicated that the isolates were AHPND positive. This study also report that all AHPND positive strains showed sensitivity to the antibiotics Tetracycline and Nalidixic Acid. The results of this study will help the farmers and policy makers to make plan to protect shrimps from AHPND and thereby sustain the shrimp farming in Bangladesh.

CitationSarder H, Khan T, Saha ML, Punom NJ, Mandal SC and Rahman MS (2016) Prevalence and antibiotic susceptibility of Aeromonas hydrophila isolated from freshwater fishes. Journal of Fisheries 4(3): 411-419. DOI: 10.17017/jfish.v4i3.2016.177 Abstract Aeromonas hydrophila is an opportunistic microorganism. It is a secondary biological agent that contributes to the occurrence of fish diseases and its deterioration. This research was undertaken to determine the prevalence of A. hydrophila in some freshwater fishes collected from three different fish markets of Dhaka City and to test their antibiotic susceptibility. Total bacterial count and total aeromonas on different aeromonas selective media were enumerated using serial dilution technique. Bacterial isolates were characterized to identify A. hydrophila using biochemical tests and with comparison to reference strain (ATCC 7966). The lowest Aeromonas count was detected to be 2.83±0.40×10 2 cfu/g in Anabas testudineus and the highest was 1.03±0.153×10 3 cfu/g in Oreochromis mossambicus. On market basis highest aeromonas count was found in Anando Bazar (8.10±1.09×10 2 cfu/g) and lowest in Hatirpool Bazar (5.63±0.90×10 2 cfu/g) with no significant difference. Maximum susceptibility to amikacin and gentamicin was observed whereas all of the isolates were found resistant to a commonly used antibiotic amoxycillin. The obtained results point that antimicrobial susceptibility was more or less similar regardless of the origin of the samples collected. All the fishes investigated in this study contained A. hydrophila in their different organs.

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Cinnamon has different biological properties such as antioxidant, antimicrobial, antidiabetic and antiallergic. This study was carried out to investigate the effect of cinnamon as feed supplement on growth performances and bacterial load of Heteropneustes fossilis. Twenty fries were stocked in each 60 litre aquarium for a rearing period of 90 days. Commercial diet was used that contains 0.0% (control), 0.5%, and 1.0% cinnamon bark powder. The diet containing 1% cinnamon resulted in greater ADG, SGR, FCR and survival rate. Whereas, the diet containing 0.5% cinnamon resulted in greater condition factor and lower FCR. In most of the cases the diet containing 1% cinnamon showed lower amount of bacterial count than the controlled condition. Cinnamon could have an antibacterial activity antagonistic to Vibrio and Aeromonas as there was no count found in fish flesh samples after 90 days of culture. The findings of this study suggest that growth performances and bacterial load of H. fossilis were better in commercial feed containing cinnamon powder. It is recommended that fish farmers can use cinnamon as feed supplement to improve growth performance and reduce bacterial load during culture of H. fossilis.

BackgroundDue to its rapid lethal effect in the early development stage of shrimp, acute hepatopancreatic necrosis disease (AHPND) has been causing great economic losses, since its first outbreak in southeast China in 2009. Vibrio parahaemolyticus, carrying the pirA and pirB toxin genes is known to cause AHPND in shrimp. The overall objective of this study was to sequence the whole genome of AHPND positive V. parahaemolyticus strains isolated from shrimp (Peneaus monodon) of the south-west region of Bangladesh in 2016 and 2017 and characterize the genomic features and emergence pattern of this marine pathogen.ResultsTwo targeted AHPND positive V. parahaemolyticus strains were confirmed using PCR with 16S rRNA, ldh, AP3 and AP4 primers. The assembled genomes of strain MSR16 and MSR17 were comprised of a total of 5,393,740 bp and 5,241,592 bp, respectively. From annotation, several virulence genes involved in chemotaxis and motility, EPS type II secretion system, Type III secretion system-1 (T3SS-1) and its secreted effectors, thermolabile hemolysin were found in both strains. Importantly, the ~ 69 kb plasmid was identified in both MSR16 and MSR17 strains containing the two toxin genes pirA and pirB. Antibiotic resistance genes were predicted against β-lactam, fluoroquinolone, tetracycline and macrolide groups in both MSR16 and MSR17 strains.ConclusionsThe findings of this research may facilitate the tracking of pathogenic and/or antibiotic-resistant V. parahaemolyticus isolates between production sites, and the identification of candidate strains for the production of vaccines as an aid to control of this devastating disease. Also, the emergence pattern of this pathogen can be highlighted to determine the characteristic differences of other strains found all over the world.

In this study, pangas and feed samples were analyzed to estimate the levels of metallic elements and to profile the human health risks due to consumption of contaminated fish. This investigation confirmed significant variations in heavy metal concentrations among different tissues of pangas in the order of Ni> Cu> Pb> Cd> Cr in pre-monsoon; and Ni> Cd= Cu> Pb= Cr in post-monsoon. Considerably higher concentrations of Pb, Cu and Cr were estimated in liver; and Cd and Ni were detected in muscle than other organs (p>0.05). Statistically significant higher amount of Cd, Ni, and Cu were observed in pre-monsoon than post-monsoon. Furthermore, three metal pairs showed significant association (Pb-Ni and Pb-Cu involved positively; Cd-Ni acted negatively). In pre-monsoon, Cd, Pb, Ni, Cu concentrations of feed significantly differed than pangas contents; whereas only Cu varied during the post-monsoon. Regression analysis revealed the significant effect of Ni content in feed on the Cu deposition of pangas (p-value 0.027, that was <0.05). For the assessment of potential human health risk of the studied metals, estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI) and carcinogenic risk (CR) indices were calculated. Studied EDI indicated that an average adult ingested a higher amount of Ni and Cu than the recommended intake limit. Nevertheless, only the higher EDI of Ni increases the value of THQ and HI than standard limit indicates adverse non-carcinogenic risk. However, lower CR of Pb confirmed no serious health hazard due to the ingestion of pangas. Factor analysis through principal component and cluster analysis suggested that higher concentrations of Pb and Ni may regulate by the feed used, geochemical properties or rapid industrialization in the study area. A proper monitoring for controlling the quality of fish feed with sustainable planning for industrialization could secure the booming of pangasius aquaculture in Bangladesh.

Background Due to its rapid lethal effect in the early stage of shrimp, acute hepatopancreatic necrosis disease (AHPND) causing great economic losses, since it first outbreak in southeast China in 2009. Vibrio parahaemolyticus , carrying the pir A and pir B toxin genes is known to cause AHPND in shrimp. The overall objective of this study was to sequence whole genome of AHPND positive V. parahaemolyticus strains isolated from shrimp ( Peneaus monodon ) of south-west region of Bangladesh in 2016 and 2017 and characterize the genomic features and emergence pattern of this marine pathogen. Results Two targeted AHPND positive V. parahaemolyticus strains were confirmed using PCR with 16S rRNA, ldh , AP3 and AP4 primers. The assembled genomes of strain MSR16 and MSR17 were comprised of total 5,393,740 bp and 5,241,592 bp, respectively. From annotation, several virulence genes involved in chemotaxis and motility, EPS type II secretion system, Type three secretion system-1 (TTSS-1) and its secreted effectors, thermolabile hemolysin were found in both strains. Importantly, the ~69 kb plasmid was identified in both MSR16 and MSR17 strains containing the two toxin genes pir A and pir B. Antibiotic resistance genes were predicted against β-lactam, fluoroquinolone, tetracycline, macrolide and cephalosporin groups in both MSR16 and MSR17 strains. Conclusions The findings of this research may facilitate the tracking of pathogenic and/or antibiotic resistance V. parahaemolyticus isolates between production sites, and the identification of candidate strains for production of vaccines as an aid to control of this devastating disease. Also, the emergence pattern of this pathogen can be highlighted to determine the characteristic differences of other strains found all over the world.

Acute hepatopancreatic necrosis disease (AHPND) is an emerging shrimp disease caused by strains of Vibrio parahaemolyticus containing a unique virulent plasmid, responsible for substantial economic losses since 2009; caused up to 100% mortality in farmed shrimp Penaeus monodon. The purpose of this study was to isolate and identify the pathogenic strain of V. parahaemolyticus causing AHPND in cultured shrimp (Penaeus monodon) using classical and molecular techniques. Samples were collected from three different locations of south-west shrimp farming regions of Bangladesh viz. Sadar Upazilla of Satkhira; Mongla and Morrelganj under Bagerhat district. In this study, three selective media were used for primary isolation of V. parahaemolyticus. Among 46 primary isolates, 18 representative isolates were checked for the species-specific detection of V. parahaemolyticus using ldh primers and all of them were found to be positive. 16S rRNA gene sequencing were used to further confirm the isolates as V. parahaemolyticus. tdh primer was used to check human pathogenicity but all 18 isolates showed negative result. The isolates were further characterized to check their AHPND positivity using AP3 and AP4 primers. Ten isolates showed positive results for AP3 (55.56%) and 9 showed positive results for AP4 (50%) which indicated that the isolates were AHPND positive. This study also reported that all AHPND positive strains were resistant to the antibiotic gentamycin but sensitive to chloramphenicol, nalidixic acid, nitrofurantoin and tetracycline. The findings of this study will help the shrimp farmers and policy makers to take proper biosecurity measures to protect shrimps from AHPND and thereby sustain the shrimp production in Bangladesh. Dhaka Univ. J. Biol. Sci. 27(1): 57-68, 2018 (January)