~ 271 ~ International Journal of Fisheries and Aquatic Studies 2015; 2(4): 271-276 ISSN: 2347-5129 IJFAS 2015; 2(4): 271-276 © 2015 IJFAS www.fisheriesjournal.com Received: 05-01-2015 Accepted: 25-02-2015 Shimaa A. H. El Far Department of Poultry and Fish diseases, Faculty of Veterinary Medicine, Alexandria University, Egypt. Riad H. Khalil Department of Poultry and Fish diseases, Faculty of Veterinary Medicine, Alexandria University, Egypt. Talaat T. Saad Department of Poultry and Fish diseases, Faculty of Veterinary Medicine, Alexandria University, Egypt. Mahmoud El-Tanekhy Department of Poultry and Fish diseases, Faculty of Veterinary Medicine, Alexandria University, Egypt. Hany M. R. Abdel-Latif Department of Poultry and Fish diseases, Faculty of Veterinary Medicine, Alexandria University, Edfina, Behera, P.O. Box: 22758, Egypt. Correspondence Hany M. R. Abdel-Latif Department of Poultry and Fish diseases, Faculty of Veterinary Medicine, Alexandria University, Edfina, Behera, P.O. Box: 22758, Egypt. Occurrence, characterization and antibiotic resistance patterns of bacterial communities encountered in mass kills of pond cultured Indian prawn (Fenneropenaeus indicus) at Damietta governorate, Egypt Shimaa A.H. El Far, Riad H. Khalil, Talaat T. Saad, Mahmoud El- Tanekhy, Hany M.R. Abdel-Latif 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. Keywords: Fenneropenaeus indicus – Bacterial infections – gill fouling – Antibiogram. 1. Introduction The world production of both captured and farmed shrimp is around 6 million tones, about 60 percent of which enters the world market. Shrimp is now the most important internationally traded fishery commodity in terms of value. Annual exports of shrimp are currently worth more than US$10 billion, or 16 percent of all fishery exports [1] . Shrimp accounts for about 20% of the value of exported fishery products over the past 20 years [2] . Imports into developed countries accounted for about 40% of intra-developed countries trade, while about 60% comes from developing countries; out of the exports from developing countries 80% goes to developed countries and only 20% stays in the group [3] . Also, shrimps are one of the major aquaculture products of export importance from the tropics. Bacteria are among the groups of microorganisms causing serious losses in shrimp culture throughout the world. Members of the genus Vibrio, including V. parahaemolyticus and V. harveyi, have been described as the main pathogenic species in shrimp and are responsible for most of the larval deaths. These pathogens cause serious infections, decreased production both in the hatchery and grow-out ponds, reduced feed conversion and growth rates in surviving individuals, thus having a negative impact on the overall financial efficiency of the business. Vibriosis is a bacterial disease caused by gram-negative, motile, facultative anaerobe bacteria of the family Vibrionaceae. It is ubiquitous throughout the world and all marine crustaceans, including shrimp, are susceptible. Vibrio species are the eminent microorganisms in the marine environment and usually constitute the majority in the normal microflora of farmed and wild penaeid shrimp. They become opportunistic pathogens when the natural defense