Basic HTML Version
Molecular Pathogens
2
et al., 2007). In addition,
V. vulnificus
is a potentially
lethal food -borne pathogen that is capable of causing
primary septicemia and necrotizing wound infections
in susceptible individuals (Ballal et al., 2010).
In recent year, vibriosis has became one of the most
important bacterial diseases in maricultured organisms,
affecting a large number of fish and shellfish (Woo
and Kelly, 1995;Wu and pan, 1997).
V.vulnificus
is a natural microflora of estuarine and
coastal marine environments worldwide and have
been isolated from sea and brackish water (Kirs et al.,
2010), which made a significant health threat to
humans who suffered from immune disorders, liver
disease and hemochromotosis (Wafaa et al., 2011).
V.alginolyticus
are widely dispersed in coastal areas
and have been associated with especially septicemia in
human.
Marine fish’s contamination with Vibrios results in
serious consequences relating to national productivity
and development. Antibiotics and other chemotherapeutic
agents are commonly used in fish farms either as feed
additives or immersion baths to achieve either
prophylaxis or therapy. It was observed that individual
and multiple antibiotic resistances were associated
with antimicrobial use. Acquired antibiotic resistance
in bacteria is generally mediated by extra
chromosomal plasmids and are transmitted to the next
generation (vertical gene transfer) and also exchanged
among different bacterial population (horizontal gene
transfer). Extensive use of these antibiotics has
resulted in an increase of drug-resistant bacteria as
well as R-plasmids (Son et al., 1997).
At this backdrop, the present work was tailored in
order to understand the status co of vibrios in marine
fish and understand the resistant pattern of isolated
vibrios against various antibiotics to unravel their
resistance pattern in antibiogram and study the impact
of ecological factors an its survivability.
1 Material and Methods
1.1 Sample collection
The sea fish samples
Upeneus sp., Rastrelliger
kanagarta, Sphyraena barracuda and Sardinella sp.,
(Locally called Nagarai, Ayalai, Ooli and Chalai) were
collected from fish market at Thirunelveli and
tuticorin in a pre sterilized polythene pack. All sea
food samples were transported in individually labelled
and sealed new plastics bags to avoid contamination.
The samples were placed in sealed container
containing ice pack and transported to the laboratory
for further analysis within 6 hours of collection.
1.2 Enrichment procedure
The enrichment procedure improves the presence of
Vibrios in seafish. 10 g of seafish muscles were taken
and ground with 90 ml of 3% NaCl containing 1%
alkaline peptone water (APW, pH: 8.6) (Adebayo –
Tayo et al., 2011). The tubes for enrichment were
incubated at 37
℃
for 18 hours (Pinto et al., 2008).
1.3 Isolation procedure
Isolation of
Vibrio
sp was made on thiosulphate citrate
bile salt sucrose agar media (TCBS, Himedia, India).
From the enrichment tube, inoculum were streaked on
TCBS agar plates and incubated at 37
℃
for 18 to 24
hours. After incubation, the suspected colony types
Vibrio
like organisms-yellow and green) were picked
out, and streaked again onto nutrient agar plus 2%
NaCl to obtain pure cultures.
1.4 Phenotypic characteristics of the bacterial
isolates and storage
Biochemical characterization of all the isolated
bacterial colonies were subjected to the following tests
with an addition of 2% NaCl in media at a final
concentration except tests for growth in 0,1,3,6,8, and
10% NaCl (Castro et al
.,
2002). The isolated bacterial
cultures were stored on nutrient agar slants with 2%
sodium chloride and 20% glycerol were prepared and
stored at 4
℃
as stocks culture for further work
(Manjusha and Sarita, 2011).
1.5 Antibiotic sensitivity test
Bacterial isolates were tested for anti microbial
sensitivity through the disc diffusion method. The
bacterial isolates were tested against the antibiotics
impregnated discs of about 6mm diameter (Himedia
Laboratories, Mumbai). Discs containing the following
antibacterial agents were placed on spread plated
Muller Hinton Agar plates (Himedia laboratories,
Mumbai) supplemented with 2% NaCl and incubated