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In the present research work, seven different antibiotics viz., Cyclohexamide, Ampicillin,
Cefotaxime, Nystatin, Pyridoxial hydrochloride, Neomycin and Chloramphenicol were used for the
analysis of morphological and histopathology studies of earthworm, Eudrilus eugeniae. These seven
antibiotics were used in two different methods, one was incorporated into the nutrient agar medium
and the other was incorporated on its habitat. In the first method, involving the incorporation into
the nutrient agar medium, the earthworms were first incubated on sterile nutrient agar medium
containing specific amount of seven different antibiotics. Every single antibiotic was used to prepare
nutrient agar plates. Earthworms were then placed on these plates and later checked for its and
morphological conditions for every 1 hour up to 24 hours. After 24 hours, it was noted that the
earthworm died in the Nystatin added agar plate while other antibiotics incorporated plate with
earthworms were observed to be alive.
The second method involves the incorporation of earthworms into their habitat. The above
mentioned seven antibiotics were taken individually and were then added to 50 ml of sterile water
and from that preparation, 1 ml was taken and added directly to the sterilized compost and mixed
well. The earthworms were later placed in those seven different antibiotics incorporated compost for
24 hours with an interval observation of every 1 hour in between. After 24 hours, it recorded that all
the earthworms inoculated into the sterile compost remained alive.
In the present study five different bacterial isolates each from inner as well as the outer regions of
the test earthworm were isolated and assayed for the antibiogram studies against the seven different
antibiotics. As the Nystatin antibiotic agar medium incubated with earthworm died the particular
antibiotic was chosen for further study was treated in earthworm by direct and indirect method. In
direct method, the antibiotic was injected in clitellum of the earthworm whereas in indirect method,
the earthworm was subjected to nystatin wash. Finally, the nystatin washed earthworms were
carried out for histopathological analysis which showed damage in the epidermal and circular
muscle layer.
Keywords: Agar-well diffusion, Antibiotics, Earthworm, Haematoxylin and eosin, Nutrient agar medium.