In vitro susceptibility of antibiotics against Vibrio spp. and Aeromonas spp. isolated from Penaeus monodon hatcheries and ponds.

Susceptibility patterns to 16 different antibiotics were investigated against pathogenic Vibrio spp. and Aeromonas spp. isolated from shrimp culture hatcheries and ponds in India. Thirteen species of Vibrio (N = 90) and two species of Aeromonas (N = 7) isolates were tested by agar disk diffusion. The results show that 100% of the isolates were resistant to ampicillin, and that 43.2% and 47.4% were sensitive to chlortetracycline and erythromycin, respectively. Susceptibility patterns of another 160 isolates belonging to the genera Vibrio and Aeromonas obtained from the water samples of shrimp hatcheries and ponds were tested against six commonly used antibiotics. Results indicate that isolates from the hatcheries were more resistant to antimicrobials than isolates from the ponds. The minimum inhibitory concentrations of five antibiotics against the different Vibrio spp. and Aeromonas spp. were determined. Ciprofloxacin was found to be the most effective in controlling the isolates from hatcheries and ponds compared with the other antibiotics used in the study. Our results reveal that antibiotic-resistant bacteria are widespread in the shrimp culture hatcheries and ponds in India. Potential risk to human health was not addressed in this study and remains to be elucidated.