Research Article Julinta et al., J Aquac Res Development 2017, 8:4 DOI: 10.4172/2155-9546.1000488 Research Article Open Access Journal of Aquaculture Research & Development J o u r n a l o f A q u a c u lt u r e R e s e a r c h & D e v e l o p m e n t ISSN: 2155-9546 Volume 8 • Issue 4 • 1000488 J Aquac Res Development, an open access journal ISSN: 2155-9546 Keywords: Aeromonas hydrophila; Oreochromis niloticus; Oxytetracycline; Oral therapy; Nephropathy; Necrotic lesion Introduction Te tilapias are freshwater fsh that belong to the family Cichlidae, and they are exclusively associated with Africa and Middle East [1]. Te Nile tilapia (Oreochromis niloticus L.) is one of the frst fsh species to be cultured in the world. Illustrations from Egyptian tombs suggested that the Nile tilapias had been cultured more than 4,000 years ago [2]. In 2010, more than 73% of total tilapia production were represented by O. niloticus [3]. Te farmed tilapia production statistics from 135 countries and territories on all continents are available currently [4]. Considering the demand for more fsh, it has become an important species for aquaculture in India [5]. Initially, tilapias were considered to be more resistant to microbial diseases. But, in recent times tilapias have been found to be susceptible to various diseases. Bacterial infections are the most serious problem in tilapia production causing 80% of fsh mortalities [2,6-7]. Aeromonas hydrophila is considered as a persuasive pathogen that causes mortalities in tilapia and other freshwater fsh [8,9]. Fish exposed to poor water quality such as high nitrite levels, low levels of dissolved oxygen, or high levels of carbon dioxide are more susceptible to infection by bacterial pathogens [2]. Most bacterial infections can be treated efectively with antibiotics. However, the farmers use a variety of aquadrugs for the control of fsh diseases [10]. Treatment of A. hydrophila is currently limited to two antibiotics, Terramycin ® , an oxytetracycline (OTC), and Remet-30 ® , a potentiated sulfonamide. Oxytetracycline is one of the USFDA (United States Food and Drug Administration) approved chemotherapeutic as an oral antibacterial to treat specifc bacterial diseases in temperate and warm water fnfsh [11-13]. Te preparation of medicated feed for use with fsh intended for human consumption is, however, regulated by the FDA [13]. Te stability of OTC in feed premixes has been evaluated and is well established at >90% retained potency afer 24 months of storage under ambient conditions [14]. Tough the efectiveness and safety levels of the FDA approved antibiotics, including OTC on temperate fsh have been established, such studies on fsh species cultured in topical condition are not attempted. Tis study was, therefore, aimed at to evaluate the efectiveness of feeds containing diferent concentrations of OTC on Nile tilapia O. niloticus against A. hydrophila infection with particular reference to histopatological alterations in kidney and muscle, and wound healing. Materials and Methods Bacterial strain Te β-haemolytic and oxytetracycline sensitive bacterial strain Aeromonas hydrophila BBT 4 K 3 (NCBI accession number KY484791) used in this study was from the collections of the Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, India. It was isolated from the kidney of haemorrhagic septicemic O. niloticus. Te isolation, identifcation and preparation of bacterial cell suspension were as described in Abraham et al. [15]. Feed top dressing As per the FDA standards [12], the medicated feeds for feeding *Corresponding author: R. Beryl Julinta, Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata-700094, West Bengal, India, Tel: +91 98832 87694; E-mail: julintaa@gmail.com Received June 03, 2017; Accepted June 28, 2017; Published June 30, 2017 Citation: Julinta RB, Abraham TJ, Roy A, Singha J, Dash G, et al. (2017) Histopathology and Wound Healing in Oxytetracycline Treated Oreochromis niloticus (L.) Against Aeromonas hydrophila Intramuscular Challenge. J Aquac Res Development 8: 488. doi: 10.4172/2155-9546.1000488 Copyright: © 2017 Julinta RB, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Antibiotics are very important tools for the control of fsh bacterial diseases. Yet, there are strict regulations controlling the use of antibiotics in aquaculture. This study assessed the effcacy oxytetracycline dihydrate (OTC) at a dose of 2 g, 4 g, 6 g and 8 g/100 pounds fsh/day against Aeromonas hydrophila challenge in Nile tilapia Oreochromis niloticus as well as the histopathological alterations in kidney and muscle, and wound healing. The commercial pellet feed was top dressed with OTC using 5 ml vegetable oil as a binder. The fsh were injected intramuscularly with A. hydrophila at ≈1 × 10 8 cells/fsh and then fed OTC feeds at 2% of their body weight for 10 days. The fsh fed with 8g OTC/100 pounds fsh/day recorded the lowest mortality (3.33%). The untreated fsh recorded 8.33% mortality. Histologically, the kidney tissues of O. niloticus exhibited nephropathy and glomerulopathy. The kidney of OTC fed groups had improved organization of nephritic tubules and glomerulus. The muscle tissues exhibited haemocyte infltration with mild necrosis initially, followed by melanization and disrupted muscle bundles. The results demonstrated that the OTC treatment for 10 days could bring out improved functioning of fsh kidneys that carry infectious agents. Within 3 days of OTC therapy, tissue reddening and infammation subsided with the formation of black scar. Full recovery of normal skin architecture was reached within 26-31 days post-injection. Based on the results, prudent use of 4-8 g OTC/100 pounds fsh/day is recommended for the control of A. hydrophila infection in O. niloticus. Histopathology and Wound Healing in Oxytetracycline Treated Oreochromis niloticus (L.) Against Aeromonas hydrophila Intramuscular Challenge Julinta RB 1 *, Abraham TJ 1 , Anwesha Roy 1 , Jasmine Singha 1 , Gadadhar Dash 1 , NageshTS 2 and Patil PK 3 1 Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, West Bengal, India 2 Department of Fisheries Resource Management, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, West Bengal, India 3 Central Institute of Brackishwater Aquaculture, Indian Council of Agricultural Research, Raja Annamalai Puram, Chennai, Tamil Nadu, India