International Journal of Aquaculture, 2016, Vol.6, No.3, 1
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3.3 Antibiotic resistance of the bacterial isolates from fish gut of
Etroplus maculatus
and
Aplocheilus
lineatus
Overall antibiotic resistance among the heterotrophic bacteria from the gut of
A. lineatus
and
E. maculatus
is
presented in Figure 4. Majority of the isolates from the gut of both fishes exhibited resistance to cefpodoxime,
meanwhile none of the isolates were resistant to gentamicin. These results corroborate with the findings of (Sahoo
and Mukherjee, 1997; Bharathkumar and Abraham, 2011). In contrast, gentamicin resistant bacteria were isolated
from the fish and the aquatic environment by DePaola et al. (1995). Resistance to cephalothin, ciprofloxacin,
tetracycline, chloramphenicol, nalidixic acid, sulfafurazole and trimethoprim was found to relatively less prevalent
among the gut associated bacteria.
Figure 4 Overall antibiotic resistances among the gut associated bacteria from
A. lineatus
and
E. maculatus
Prevalence of antibiotic resistance among the gut associated bacteria from
A. lineatus
and
E. maculatus
is given in
Table 1; Table 2
Lactobacillus
sp., isolated from the gut of
A. lineatus
exhibited resistance to 8 antibiotics tested
(Table 1) and they are the only isolates shows resistant to ciprofloxacin (Cip).
Bacillus sp.,
exhibited resistance to
6 antibiotics among 11 tested and showed maximum resistance against Cefpodoxime and Nalidixic acid (Na) and
moderate resistance against antibiotics like cephalothin (Cep), cefpodoxime (Cpd), trimethoprim (Tr) and
chloramphenicol (C).
Aeromonas
sp., exhibited resistance to cephalothin, cefpodoxime, nalidixic acid and
carbenicillin. This result is in contrast to the study of Peterson and Dalsgaard (2003), they observed poor
resistance of
Aeromonas
to all antibiotics.Some isolates of
Micrococcus
exhibited resistance to 4 antibiotics, while,
Pseudomonas
sp
.,
exhibited resistance to 3 antibiotics with 100% resistance. All bacterial isolates shows
resistance to cephalothin other than
Corynebacterium
, they shows resistance only against carbenicillin (Cb) and
cefpodoxime (Cpd). Except
Vibrio spp.
, all the other species exhibited resistance to carbenicillin with high degree
of resistance, while they show 100% resistance against streptomycin (S). Among the various genera of bacteria
encountered in the gut of
E. maculatus
, members of the family Enterbacteriaceae were found to have acquired
relatively higher resistance (Table 2).
Bacillus
which was found to be the dominant genus among the gut
associated bacteria of
E. maculatus
also showed considerable resistance to various classes of antibiotics.
4 Multiple antibiotic resistance among the gut associated bacteria
Table 3 represents the MAR index and resistance pattern of bacterial isolates from the gut of
A. lineatus
. MAR
index varied from 0.09 to 0.36. Thirteen different resistance patterns were exhibited by these isolates of which the
most frequently observed pattern was CepCpd (27%) followed by CepCpdTr (11.5%). Nearly 38% of the isolates
