Bacterial and viral diseases constitute a major factor limiting the successes of shrimp farming industry. In this context, Identification of drug resistant pathogens and determination of the pathogenic processes of shrimp are fundamental for further progress in the disease management. They could be valuable in the evaluation of their epidemiology and control measures. Water samples from the aquaculture environment were contaminated with Vibrio anguillarum, V. damsela, V. furnissii, Aeromonas hydrophila and A. sobria. Both Vibrio spp and Aeromonas spp were shown to be pathogenic and to cause mortality to the infected post larval P. monodon. Vibrio spp. were shown to grow in TCBS agar, zobell’s marine agar and blood agar while Aeromonas spp. additionally exhibited growth in blood agar with selective supplement ampicillin (10 µg/ml) and showed a zone of clearance in DNase agar. LD50 values of V. anguillarim, V. damsela, V. funrissii, A. hydrophila and A. sobria to post larval P. monodon were determined as 1.1 x 105, 2.7 x 105, 6.0 x 105, 8.5 x 104, and 7.5 x 104 bacterial cells/ml respectively. Ciprofloxacin and streptomycin were found to be the most effective antibiotics in the reduction of the mortality of experimentally infected post larvae. The growth of Vibrio spp was inhibited by nifurpirinol (prefuran) at 25 µg/ml, oxytetracycline at 13 µg/ml, erythromycin phosphate at 4 µg/ml, chloramphenicol at 12 µg/ml, streptomycin at 2 µg/ml, and ciprofloxacin at 1 µg/ml. While the growth of Aeromonas spp was inhibited by nifurpirinol (prefuran) at 24 µg/ml, oxytetracycline at 14 µg/ml, erythromycin phosphate at 5 µg/ml, chloramphenicol at 12 µg/ml, streptomycin at 2 µg/ml, and ciprofloxacin at 1 µg/ml. Vibrio spp. was sensitive to o/129 vibriostatic agent (150 µg) whereasAeromonas spp. was resistant to it. The pathogenic bacteria viz. Vibrio spp and Aeromonas spp could be controlled to some extent with judicious use of effective antibiotics to improve the health status of shrimp in culture conditions and can have a positive impact in the areas of sustainable aquaculture environment and development.
Author(s) Details
P. Ramasamy
Research and Development Wing, Sree Balaji Medical College and Hospital, India.
D. R. Gunasekaran
Research and Development Wing, Sree Balaji Medical College and Hospital, India.
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