International Journal of Aquaculture, 2013, Vol.3, No.17, 92
-
100
http://ija.sophiapublisher.com
92
Research Report Open Access
Distribution, Extracellular Virulence Factors and Drug Resistance of Motile
Aeromonads in Fresh Water Ornamental Fishes and Associated Carriage Water
Nifty John , A. A. M. Hatha
Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Lakeside Campus, Cochin University of Science and Technology,
Cochin-682 016, Kerala, India
Corresponding author email:
mohamedhatha@gmail.com;
Authors
International Journal of Aquaculture, 2013, Vol.3, No.17 doi: 10.5376/ija.2013.03.0017
Received: 30 May, 2013
Accepted: 3 Jun., 2013
Published: 20 Jun, 2013
Copyright © 2013
John. This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
John, 2013, Distribution, Extracellular Virulence Factors and Drug Resistance of Motile Aeromonads in Fresh Water Ornamental Fishes and Associated
Carriage Water, International Journal of Aquaculture, Vol.3, No.17 92-100 (doi: 10.5376/ija.2013. 03.0017)
Abstract
During last decades there has been a continuous growth of aquaculture industries all over the world and taking into
consideration the spurt in freshwater ornamental fish aquaculture and trade in Kerala, the present study was aimed to assess the
prevalence of various motile
Aeromonas
spp. in fresh water ornamental fishes and associated carriage water. The extracellular
virulence factors and the antibiogram of the isolates were also elucidated. Various species of motile aeromonads such as
Aeromonas
caviae
,
A. hydrophila
,
A. jandaei
,
A. schubertii
,
A. sobria
,
A. trota
and
A. veronii
were detected
.
Aeromonas sobria
predominated
both fish and water samples. Extracellular enzymes and toxins produced by motile aeromonds are important elements of bacterial
virulence. The production of extracellular virulence factors - proteases, lipase, DNase and haemolysin by the isolates were studied.
All the isolates from both fish and water samples produced gelatinase and nuclease but the ability to produce lipase, caseinase and
haemolysins was found to vary among isolates from different sources. Among the 15
antibiotics to which the isolates were tested, all
the isolates were found to be sensitive to chloramphenicol, ciprofloxacin and gentamicin and resistant to amoxycillin. Local aquarists
maintain the fish in crowded stressful conditions, which could trigger infections by the obligate/ opportunistic pathogenic members
among motile aeromonads.
Keywords
Ornamental fish; Motile aeromonads; Antibiotic resistance; Diseases
Introduction
Keeping colourful and fancy fishes known as
ornamental fishes, aquarium fishes, or live jewels is
one of the oldest and most popular hobbies in the
world. The growing interest in aquarium fishes has
resulted in a steady increase in aquarium fish trade
globally. The global scope and scale of the ornamental
fish trade and growing popularity of pet fish are strong
indicators of the myriad economic and social benefits
the pet industry provides. Culture of ornamental fish
in the backyards of households requires very little
space, skill and time, and has the potential to improve
the economic condition of the household. ‘Earning a
regular income, unlike seasonal work in agriculture,
provides further motivation (Shaleesha and Stanley, 2000).
Aquaculture is an emerging industrial sector which
requires continued research with scientific and
technical developments, and innovation. Over one
billion ornamental fish comprising more than 4000
freshwater and 1400 marine species are traded
internationally each year, making it one of the most
important components of the global fish trade.
Freshwater species make up 90% of this trade as they
are the most popular and widely kept aquarium pets
worldwide (Krishnakumar et al., 2009). The trade in
ornamental (pet) fish is greater than 1 billion animals
per year globally. More than 45 million fish per year
are imported into the United Kingdom (UK) alone
from a wide range of countries, in particular those in
South East Asia (Wittington and Chong, 2007).
Fish diseases are a scourge of ornamental fish industry
bringing huge economic loss. Bacterial organisms
may be the primary cause of disease, or they may be
secondary invaders. The majority of bacterial fish
pathogens are natural inhabitants of the aquatic
environment. Infections caused by motile members of
the genus
Aeromonas,
are amongst the most common
and troublesome diseases diagnosed in cultured warm
water fishes and have been referred to by various
names
,
including motile aeromonad septicemia (MAS),
motile aeromonad infection (MAI), hemorrhagic