International Journal of Aquaculture, 2013, Vol.3, No.17, 92
-
100
http://ija.sophiapublisher.com
94
Figure 1 Distribution of
Aeromonas
spp. in fish and water
samples
Prevalence of motile aeromonads at various parts of
the body of fresh water ornamental fishes is given in
Figure 2.
A. hydrophila, A. veronii
and
A. jandaei
were frequently encountered on gill surface when
compared to body surface and intestine.
Figure 2 Distribution of
Aeromonas
spp. in the body surface,
gill and intestine of fishes
1.2
Extracellular Virulence Factors of
Aeromonas
Species
All the isolates of
Aeromonas
spp. obtained exhibited
gelatinase and DNase activity. All the isolates of
Aeromonas sobria
exhibited caseinase and β
haemolysin production. Similarly all the isolates of
A.
hydrophila
and
A. jandaei
were capable of producing
β haemolysin. β haemolysin production was
infrequent in
A. caviae.
Lipase was produced by all
the isolates of
A. hydrophila, A. jandaei
and
A. veronii
but their
production among the isolates of other spp.
varied. The production of extracellular virulence
factors by the
Aeromonas
isolates obtained from fish and
water samples are given Table 1 and Table 2 respectively.
1.3
Antimicrobial Resistance
All the aeromonad isolates tested were resistant to
amoxycillin and sensitive to ciprofloxacin,
chloramphenicol and gentamicin regardless of their
source. While all the
Aeromonas
isolates from water
were sensitive to nitrofurantoin, 1.14% of isolates
from fish samples was resistant to nitrofurantoin.
Resistance to ceftazidime was found in 13.33% of A
.
veronii
and 5.63% of
A. sobria
isolates from fish
samples and 8% of
A.
veronii
isolates from water
samples. All the other isolates were sensitive to this
antibiotic. All the isolates except 3.63% of
A. caviae
from fish samples and 20% of
A. hydrophila
, 12.69%
Table 1 Prevalence of extracellular
virulence factors among motile aeromonads from ornamental fish samples
Aeromonas
spp.
Percentage of motile aeromonads producing virulence factors
Gelatinase
Caseinase
Lipase
DNase
Haemolytic activity
A. sobria
100
100.00
98.59
100
100.00
A. caviae
100
52.73
89.09
100
72.72
A. jandaei
100
83.33
100.00
100
100.00
A. trota
100
80.00
93.33
100
86.66
A. veronii
100
86.66
100.00
100
93.33
A. hydrophila
100
90.00
100.00
100
100.00
A. shubertii
100
66.67
66.60
100
100.00
Table 2 Prevalence of extracellular virulence factors among motile aeromonads from carriage water samples
Aeromonas
spp.
Percentage of motile aeromonads producing virulence factors
Gelatinase
Caseinase
Lipase
DNase
Haemolytic activity
A. sobria
100
100.0
98.40
100
100.0
A. caviae
100
60.0
90.00
100
70.0
A. jandaei
100
100.0
100.00
100
100.0
A. trota
100
87.5
93.75
100
87.5
A. veronii
100
88.0
100.00
100
92.0
A. hydrophila
100
88.0
100.00
100
100.0
A. shubertii
100
62.5
87.50
100
75.0