Detection of virulence genes, antimicrobial susceptibility and pathogenicity of Aeromonas veronii isolates from Labeo rohita and Catla catla Chethurajupalli Lavanya1,*, Tambireddy Neeraja2, Ramana T.V.3, Dasari Mamatha4, Boda Satyanarayana5, Narra Mohana Swapna6, Srinivasulu Ramadasu Sravani6, Bheemeswararao K.6 1Department of Aquatic Animal Health Management, College of Fishery Science, Andhra Pradesh Fisheries University, Muthukur-524 344, Andhra Pradesh, India 2Fisheries Research Station, Andhra Pradesh Fisheries University, Undi-534 199, Andhra Pradesh, India 3Andhra Pradesh Fisheries University, Vijayawada-520 001, Andhra Pradesh, India 4Department of Aquaculture, College of Fishery Science, Andhra Pradesh Fisheries University, Muthukur-524 344, Andhra Pradesh, India 5Department of Economics, West Bengal University of Animal and Fishery Science, Kolkata-700 037, West Bengal, India 6Department of Fisheries Resource Management, College of Fishery Science, Andhra Pradesh Fisheries University, Muthukur-524 344, Andhra Pradesh, India *Corresponding Author: Chethurajupalli Lavanya, Department of Aquatic Animal Health Management, College of Fishery Science, Andhra Pradesh Fisheries University, Muthukur-524 344, Andhra Pradesh, India, Email: kavyaaa029@gmail.com
Online Published on 5 January, 2024. Abstract Background Aeromonas veronii is the most common bacterium responsible for diseases in freshwater fish rearing systems. Multiple factors can be involved in the virulence processes of Aeromonas bacteria. Hence, the purpose of the present investigation was to evaluate the virulence genes, antimicrobial susceptibility and pathogenicity of A. veronii isolated from freshwater fishes. Methods In this investigation, we isolated A. veronii from cultured freshwater fishes, Labeo rohita and Catla catla. A. veronii was identified by bacterial staining and culture characteristics. In addition, Polymerase chain reaction (PCR) was used to evaluate the distribution of nine virulence genes including aerolysin, cytotonic enterotoxin (442, 272 bp), elastase, enolase, flagellin, lipase, serine protease and DNase. Result A total of 88 A. veronii strains were isolated, which includes 56 strains from rohu and 33 strains from catla. The strains were Gram-negative, rod-shaped, motile bacteria and the colonies are yellow on blood agar. All the A. veronii strains were positive for at least one or more virulence genes tested. The isolates carried more virulence genes, especially in the combination of aer, alt, ela, lip, AhyB genes were found to be more virulent. Antimicrobial susceptibility to 17 antibiotics was determined and the strains of A. veronii showed 100% resistance to tetracycline, pencillin and β-lactum group of antibiotics. In addition, multiple antibiotic resistance (MAR) indexes ranged from 0.24 to 0.76, suggesting that they originated from high risk contaminated zones were (W. Godavari and Nellore districts) antimicrobials are often used. Top Keywords Aeromonas veronii, Antimicrobial susceptibility test, Catla catla, Labeo rohita, Pathogenicity studies, Virulence genes. Top |