Page 162 - WSAVA2017
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An Urban Experience
C. Walster1
1Stafford, United Kingdom
Chris Walster BVMS MVPH CertAqV MIFM MRCVS The Island Veterinary Associates
132 Lichfield Road
Stafford ST17 4LE
Pet or ornamental fish have long been recognised as assisting in reducing stress in doctor’s and dentist’s surgeries. The trade and hobby also assists in protecting the environment through providing trade opportunities for indigenous people with Project Piaba in the Amazon rainforest being the obvious example to cite. However, concerns have been raised since the early 1970’s
over the use of antimicrobials in fish, and in particular aquaculture. To date the evidence appears conflicting and inconclusive although when reading the literature, each side of the argument hold strong views. Putting aside these arguments, using antibiotics can create antimicrobial resistance, and as veterinarians we have
a duty to minimise that risk. This presentation looks briefly at some of the issues that arise through the trade and the treatment of ornamental fish that could cause antimicrobial resistance and their potential impact on people.
Well over 20 genera of bacteria have been isolated from fish with the most common isolates in clinical disease being Aeromonads, Vibrio sp., Flavobacterium columnare, Streptococcus sp. and Mycobacterium sp.
Aeromonads are commonly isolated in cases of ulcer disease and septicaemia in fresh water fish and are ubiquitous in the environment being found in water and soil. A. hydrophila is the most commonly isolated of this group and is generally considered to be an opportunistic pathogen. Whilst A. hydrophila is recognised as a cause of gastroenteritis in people, and can cause urinary tract and skin infections in the immunocompromised, it is not reported as a zoonotic disease. Reported resistance amongst aeromonads is variable but they are considered inherently resistant to β-lactam antibiotics i.e. penicillins and cephalosporins.
Vibrios are the marine environment equivalent of aeromonads and cause similar conditions in fish with chronic infections sometimes produce granulomas in muscle tissue. Fish pathogenic vibrios are not usually considered zoonotic although vibrios typically cause illness in people who eat contaminated seafood. The three of most concern would be: V. cholerae the cause of Cholera, V. parahaemolyticus which causes non-bloody diarrhoea and V. vulnificus which causes an often fatal septicaemia in immunocompromised individuals.
Flavobacterium columnare the cause of Columnaris Disease (Cotton Wool Disease and Saddleback Disease from the appearance of the lesions) is most often
seen when fish are stressed due to poor water quality, shipping or poor nutrition. It is commonly seen as part of “New Tank/Pond Syndrome” which occurs prior to the new system’s filter can handle the biological load. As such, it is a management issue.
Streptococcus sp. (Streptococcosis) is sometimes
seen in warm water or tropical collections as infections appears to be dependent on water temperature. Some Streptococcus such as S. iniae can cause serious illness in people including toxic shock syndrome.
Mycobacteriosis is probably more common than diagnosed as the bacteria are prevalent in the environment and infection rates can be as high as 30% in fish produced in earthen ponds. Generally, it is an
end stage disease in fish suffering from chronic “poor doing”. When transmitted to people, treatment can mean prolonged courses of antibiotics and even amputation of digits or limbs.
Although the use of antibiotics by ornamental fish veterinarians is very low, probably all classes of antibiotics have been used in ornamental fish at one time or another, and there has long been usage by hobbyists from other sources, due to a lack of interest from the profession, which has led to wide-spread issues with resistance. Currently the most frequently used antibiotics either separately or in combination are:
Flouroquinolones – Ciprofloxacin/Enrofloxacin which is used to treat aeromonad disease both in fish and people.
Aminoglycosides – kanamycin, amikacin, gentamicin. Streptomycin and neomycin are rarely used due to resistance. Aminoglycosides are used in people to treat multi-drug resistant tuberculosis.
Amphenicols – Florfenicol is generally used in veterinary medicine applications although some authors, and it is disputed, blame its use in aquaculture for the occurrence of the flo gene in Salmonella typhimurium DT104.

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