Comparative analysis of virulence genes, antibiotic resistance and gyrB-based phylogeny of motile Aeromonas species isolates from Nile tilapia and domestic fowl

The nucleotide sequence analysis of the gyrB gene indicated that the fish Aeromonas spp. isolates could be identified as Aeromonas hydrophila and Aeromonas veronii biovar sobria, whereas chicken Aeromonas spp. isolates identified as Aeromonas caviae. PCR data revealed the presence of Lip, Ser, Aer, ACT and CAI genes in fish Aer. hydrophila isolates, ACT, CAI and Aer genes in fish Aer. veronii bv sobria isolates and Ser and CAI genes in chicken Aer. caviae isolates. All chicken isolates showed variable resistance against all 12 tested antibiotic discs except for cefotaxime, nitrofurantoin, chloramphenicol and ciprofloxacin, only one isolate showed resistance to chloramphenicol and ciprofloxacin. Fish Aeromonads were sensitive to all tested antibiotic discs except amoxicillin, ampicillin-sulbactam and streptomycin.