Antibiotic and Heavy Metal Resistance in Bacteria from Organs of Sewage Fed Farm Fishes

Abstract

Bacterial populations from organs (viz., liver, spleen, kidney and gill) of Clarias batrachus of the sewage fed water areas near IISCo slag disposal site, Dharampur on northern side of Damodar River, Asansol, West Bengal, India, were enumerated, followed by determination of resistance for antibiotics and heavy metals. Maximum resistance is shown against ampicillin (95%) and minimum against ciprofloxacin (5%). Most of the isolates exhibited an increasing order of tolerance for the metals (µg/mL) copper (200), cadmium (200), iron (400) and chromium (400), with minimum inhibitory concentration (MIC) ranging from <50 to 1600 µg/mL. A total of 100 bacteria have been successfully isolated from internal organs of Clarias batrachus (Aeromonas species (20%); Escherichia coli, (45%); Bacillus species (4%); Pseudomonas aeruginosa (6%), Staphylococcus aureus (18%) and coagulate-negative Staphylococci aureus (7%)). In terms of antibiotic susceptibility testing, each isolate was tested against 10 antibiotics. The multiple antibiotic resistance (MAR) index of the isolated bacterial ranged from 0.2-0.7. These observations indicate that the bacteria isolates are from a high risk source where antibiotics are frequently used, possibly from sewage effluents. Significant occurrence of bacterial population in organs of fish with high incidence of resistance for antibiotics and heavy metals may pose risk to fish fauna and public health.