Acute hepatopancreatic necrosis disease (AHPND) has recently emerged as a serious disease of cultured shrimp. A total of 19 lactic acid bacteria (LAB) strains isolated from shrimp samples were characterized based on morphological characteristics, biochemical tests, sequencing analysis, and their ability to antagonize Vibrio parahaemolyticus, which causes AHPND in whiteleg shrimp. Results from the agar well diffusion method indicated that 3 out of 19 isolated LAB strains showed the highest antagonizing ability against AHPND V. parahaemolyticus strain with an inhibition zone diameter ranging from 18 to 20 mm. Experiments where shrimps were given feed supplemented with these LAB strains and challenged with AHPND strain showed high survival rates (approximately 80.0%), which were not significantly different as compared to those recorded in the negative control treatment (86.6%), but significantly different to those recorded in the positive control treatment (40.6%) after 16 days of the experiment. However, the histological images of shrimp hepatopancreas indicated that the infection rate significantly reduced from 60.0% to 11.1% in shrimps fed with LAB-supplemented feeds and challenged with AHPND V. parahaemolyticus strain as compared to those in the positive control treatment. A polymerase chain reaction (PCR) and 16S rRNA gene sequencing confirmed the identification of LAB strain. These results can be applied in further experiments to investigate the ability of L. plantarum in preventing AHPND in intensively cultured whiteleg shrimp.

This study aimed to evaluate the growth, survival rate, and resistance to acute hepatopancreatic necrosis disease (AHPND) of white leg shrimp (Penaeus vannamei) by using Lactobacillus plantarum, Lactobacillus fermentum, and Pediococcus pentosaceus mixed with feed, and at the same time supplying CNP in a ratio of 15:1:0.1 to the water. As a result, the treatments that shrimp were fed with feed containing lactic acid bacteria (LAB), especially L. plantarum, have increased shrimp growth, total hemocyte cells, granulocyte cells, and hyaline cells significantly (p < 0.05) in comparison to the control group. The supply of CNP to the water has promoted the intensity of V. parahaemolyticus effects on shrimp health and significantly decreased total hemocyte cells, granulocyte cells, and hyaline cells by 30–50% in the period after three days of the challenge, except in L. plantarum treatment, which had only a 20% decrease compared to other treatments. In CNP supplying treatments, the AHPND infected rate and mortality of shrimp were higher than those in other treatments. In summary, the supply of CNP had significantly reduced the shrimp’s immune response and promoted the susceptibility of shrimp to AHPND in both cases of use with and without LAB-containing diets.

The study was conducted to evaluate the susceptibility of 58 Vibrio parahaemolyticus bacterial isolates to 16 antibiotics. These bacterial isolates were recovered from diseased shrimp which displayed typical pathology of AHPND such as hepatopancreatic atrophy, empty gut, and hepatopancreatic changes including hemocytic infiltration and bacterial infection. Results of antibiotic susceptibility testing by the disk diffusion method showed that single resistance to tested antibiotics was relatively rare. The bacterial strains were resistant to amoxicillin (100%), cephalexin (100%), Sulfadiazine Sodium (94.7%), and Erythromycin (87.7%). Sensitivity of tested strains was recorded with doxycycline (84.2%) and oxytetacylin (49%). The minimum inhibitory concentrations (MICs) were determined for the sensitive isolates using a broth macro dilution method. The majority of tested isolates had an MIC value of 2μg/mL with doxycycline. The current study suggests caution in the use of antibiotics for the prevention and treatment of AHPND in shrimp farming.

This study was conducted to determine the effect of different salinities on striped catfish (Pangasianodon hypophthalmus) susceptibility to hemorrhagic disease causing by Aeromonas hydrophila bacteria. The experiment was set up in plastic tanks at various salinities (0, 3, 5, 8, 11 and 14‰). Experimental fish (about 25 ± 0.8g/fish) were challenged with A. hydrophila bacteria by intramuscular injection. After infection, the mortality and disease signs were recorded for 14 days. At the same time, bacteria re-isolation and re-identification were carried out with infected fish samples that displayed signs of lethargy, disorientation, hemorrhagic in anal, peritoneal sinus and spleen. Recorded cumulative mortality after 14 days was 86.7% at salinity 0‰ and 8.3% and 11.7% at salinities 11 and 14‰, respectively. At higher salinity, striped catfish is less susceptible to A. hydrophila bacteria than at lower salinities.