Monitoring Antibiotic Use and Residue in Freshwate

Authors: Dang Kim Pham Jacqueline Chu Nga Thuy Do François Brose Guy Degand Philippe Delahaut Edwin De Pauw Caroline Douny Kinh Van Nguyen Ton Dinh Vu MarieLouise Scippo Heiman F L Wertheim

Publish Date: 2015/01/06

Volume: 12, Issue: 3, Pages: 480-489

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Abstract

Vietnam is an important producer of aquaculture products and aquatic products are essential to the Vietnamese diet However Vietnam also has very little enforced regulation pertaining to antibiotic usage in domestic aquaculture which raises concerns for antibiotic resistance in pathogenic bacteria In this study analysis was conducted on the presence of antibiotic residues in domestically sold fish and shrimp raised in freshwater farms in Vietnam and an assessment of farmers’ knowledge of proper antibiotics usage was performed The results indicated that a quarter of tested aquaculture products were antibiotic screening test positive and there is a general lack of knowledge about the purpose and proper usage of antibiotics by aquaculture producers Farmers’ decisionmaking processes about antimicrobial use are influenced by biased sources of information such as drug manufacturers and sellers and by financial incentivesAquaculture production is an important source of pollution of veterinary medicines into the environment Pruden et al 2013 Rico and Van den Brink 2014 About 90 of the global aquaculture production is produced in Asia Thuy et al 2011 According to 2009 statistics from the Food and Agriculture Organization of the United Nations FAO Vietnam has become the third largest producer of aquaculture products behind China and India Anonymous 2009 As of 2010 there are 37142 fish farms in Vietnam which produce over 2700 thousand tons of aquatic products per year Anonymous 2010b While a large amount of Vietnam’s aquatic products are exported the demand in domestic markets is also high as aquatic products are an essential part of the Vietnamese diet Results of a global survey on antimicrobial use in aquaculture showed high use of antibiotics in fish and shrimp farming including prohibited drugs Tusevljak et al 2013 and this raised critical human health concerns Therefore understanding the processes through which aquatic animals such as finfish and shrimp are raised and eventually brought to the dinner table is of extreme importanceA large number of aquaculture farms in Vietnam are highly intensive in order to increase the yield per unit area In a study on intensive shrimp farming in the Mekong Delta many farmers are attracted to the initially high yields and profits brought by intensive farming Lan 2013 However these yields decrease and the profits disappear in less than a decade Nguyen and Ford 2010 Thus intensive shrimp farming is not as profitable or sustainable as farmers would expect An important factor that contributes to this drop in yield is disease outbreaks which in turn are exasperated by the high stock density of intensive farming Subasinghe et al 2001 Nguyen and Ford 2010 In attempt to salvage their farms and improve yields farmers resort to using a variety of antibiotics A study conducted on antibiotic contamination in northern Vietnam indicates the presence of three major antibiotic classes in aquatic environments sulfonamides diaminopyrimidine trimethoprim and macrolides Hoa et al 2011 Research by Le and Munekage on shrimp farms in mangrove areas in Vietnam indicates the presence of similar antibiotics in both northern and southern Vietnam Le et al 2005 In addition to sulfonamides and trimethoprim they also detected quinolones norfloxacin and oxolinic acid Le et al 2005The use of antibiotics in aquaculture systems can create serious economic and health problems Antibiotic residues have been found in several aquatic products from Vietnam and other Asian countries CanadaCanada et al 2009 Won et al 2011 He et al 2012 Because of stringent regulations from the US and European Union EU the issue of antibiotic residues in aquatic products for export has been mostly resolved however there are no such wellenforced regulations for Vietnam’s domestic markets Since fish and other aquatic products represent a very large portion of their diet Vietnamese people are potentially being exposed on a daily basis to antibiotic residues which can even in subtherapeutic concentrations lead to an increase in antibiotic resistance Van Anrooy 2003 Pruden et al 2013The main danger of antibiotic use is the development and selection of antibiotic resistant pathogens Since many of the antibiotics used are nonbiodegradable industrial antibiotics used in aquaculture farms can place intense selective pressure on aquatic microbial populations The presence of a large number of antibiotic resistance genes in these populations is evidence of this selective pressure Zhang et al 2009 Pruden et al 2013 The situation in Vietnam is amplified by the integrated agricultureaquaculture IAA farming system encouraged by the government which often involves an aquaculture system that is sustained through the addition of human and livestock waste This creates an environment that greatly increases the ease through which antibiotic resistance genes present in livestock or humans are transferred to aquaculture and from there into waterbodies that is used by humans and animals for consumption Hoa et al 2011 These antibiotic resistance genes can be easily transferred to both human and animal pathogens creating a severe health risk by greatly limiting the antibiotics that can be used to treat infectious diseases Zhang et al 2009 Pruden et al 2013Due to the lack of regulation there is very little information about antibiotics used in aquaculture for the domestic markets of Vietnam ad whether these is any antibiotic residue present This study attempts to address this issue by providing field research on antibiotic use in freshwater aquaculture as well as a laboratory analysis for antibiotic residue in fish and shrimp destined for Vietnamese domestic marketsWe conducted two studies 1 a crosssectional study was conducted from July 2011 to August 2011 to determine how antimicrobials are used on aquaculture farms and to determine the knowledge of Vietnamese aquaculture farmers had on the purpose and safety of antibiotics usage in freshwater farming 2 sampling of fish and shrimp from regional fresh markets for antibiotic residue analysis

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