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.

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.

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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.