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20201
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Subject: Aquaculture × Author: SRUTHI, PERLA × Start date: 2020 ×
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    ThesisItemOpen Access
    CHARACTERIZATION AND ANTIMICROBIAL RESISTANCE OF AEROMONAS SPECIES ISOLATED FROM CULTURED FRESHWATER FISHES
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2020-12) SRUTHI, PERLA; Neeraja, T (MAJOR); Haribabu, P; Balasubramanian, A
    Pathogenic Aeromonas species are causing significantly high mortalities and economic losses among the cultured freshwater fish in India and Andhra Pradesh. The aim of the present study was to identify the Aeromonas species isolated from cultured freshwater fishes majorly exhibiting bacterial haemorrhagic septicaemia, abdominal dropsy, tail rot and fin rot in two districts viz., West Godavari and SPSR Nellore districts of Andhra Pradesh, India. The diseased fish species collected from farms were Catla catla (catla), Labeo rohita (rohu), Piaractus brachypomus (pacu) and Pangasius hypophthalmus (pangas). Further, the resistance of the isolated Aeromonas spp. to the currently available antimicrobial therapeutics was determined. In the present study, 15 species of Aeromonas were isolated viz., Aeromonas allosacharrophila (n=3), A. aquariorum (n=2), A. caviae (n=1), A. enchelia (n=1), A. jandaei (n=3), A. media (n=2), A. molluscorum (n=3), A. piscicola (n=1), A. popoffii (n=3), A. sobria (n=3), A. schubertii (n=6), A. tecta (n=9), A. trota (n=3), A. veronii biovar sobria (n=5) and A. veronii biovar veronii (n=13). The Aeromonas species isolated on RS medium and GSPA medium were identified and characterized by conventional biochemical tests. The study on prevalence of Aeromonas spp. was carried out for a period of 7 months from September 2019 to March 2020 in the above two districts revealed that the highest prevalence was recorded in A. veronii bv. veronii. Significantly higher prevalence (P 0.05) with the latter species. Further, prevalence of Aeromonas spp. were significantly different (p <0.05) with respect to fish species and geographic location. In vitro antibiotic resistance study revealed that all the isolates of 15 Aeromonas spp. were highly resistant to ampicillin, amoxyclav and oxytetracycline. Further, all the Aeromonas spp. were found multiple antibiotic resistance (MAR). The MAR index of more than 0.2 was observed in all the isolates of Aeromonas spp. except A. piscicola. It indicates that these Aeromonas spp. might have originated from high risk sources of contamination. Haemolytic activity assay revealed that A. veronii bv. sobria (60%), A. aquariorum (50%), A. jandaei (33.3%), A. sobria (33.3%) and A. tecta (22.22%) were found to be β-haemolytic. However, majority of the Aeromonas spp. isolates were found α- haemolytic.