Occurrence, characterization and antibiotic resistance patterns of bacterial communities encountered in mass kills of pond cultured Indian prawn (Fenneropenaeus indicus) at Damietta governorate, Egypt

Abstract

Infectious diseases especially those caused by bacterial and viral pathogens are considered to be serious economic loss factors in shrimp farming. In our investigation, Mass kills of cultured Indian Prawns (Fenneropenaeus indicus) (F. indicus) were observed during winter season last December 2014, whereas there was sharp decrease in water temperature (17–18 0 C) at Damietta governorate, Egypt. Samples were subjected to full clinical, bacteriological and histopathological examinations. Water samples were taken to determine any physicochemical abnormalities as well as heavy metal contents. Results showed that the infected F. indicus have darkening of the hepatopancreas, gill fouling, dark discoloration of the carapace, loss of the abdominal appendages and tail necrosis. Bacterial communities retrieved were belonged to Vibrio, Enterococcus and Pseudomonas genera. Their prevalence % was found to be as following; V. harveyi (56%), V. parahaemolyticus (12%), V. vulnificus (17%), E. faecalis (7%) and Ps. fluorescence (8%). Antibiogram testing indicates that all bacterial isolates were markedly sensitive to Florfenicol, Cephradine and Norfloxacin, while resistant to Gentamycin, Oxytetracycline and Amoxicillin. Water examinations revealed elevated nitrite (NO2), unionized ammonia (NH3), organic matter and hydrogen sulphate as well as Copper (Cu), Iron (Fe) and Cadmium (Cd). We can conclude that the abrupt change in the physicochemical properties of water can be considered as stress factors which suppress the immune status of the Indian prawns, so that bacterial pathogens were encountered.