Antibiotic and metal resistance offered by Aeromonas species isolated from edible fishes in Chennai, Tamil Nadu: A field investigation

Aeromonas species are common contaminants of fish and seafood. This study presents key findings of the Aeromonas species that were isolated from the organs of fishes collected from Kasimedu region in Chennai, Tamil Nadu, India. In this study, bacterial isolates from intestines and gills of three different edible fish varieties - Sardinella longiceps, Lutjanus gibbus and Pseudocaranx dentex were isolated. The isolates were identified to belong to gram negative Aeromonas species through biochemical tests. All the isolates were tested for antibiotic sensitivity for ten different antibiotics which includes Ampicillin, Chloramphenicol, Erythromycin, Gentamycin, Penicillin-G, Streptomycin, Tetracycline, Fluoroquinolone, Cephalosporin and Carbapenam. Metal resistance was checked for five metals namely Copper (Cu), Chromium (Cr), Lead (Pb), Manganese (Mn) and Nickel (Ni). All the strains exhibited Multiple Antibiotic Resistances (MAR) to at least two antibiotics. The Aeromonas strains showed sensitivity to Erythromycin and Gentamycin. The MAR index for the three strains was calculated as 0.52, 0.47 and 0.28 respectively. All the three MAR indices values were seen to be greater than 0.2 which indicates that the isolate has originated from a high-risk source of contamination. Thus, the results obtained clearly show that the fish samples collected is highly contaminated with antibiotic and metal resistant Aeromonas bacterial species.