Due to the increase in pharmaceuticals and antibiotics in surface water and wastewater, it is giving a place for the bacteria to become antibiotic resistant to a particular antibiotic or to a group of antibiotics by the mutation of their genes. In this study, minimum inhibition concentrations correspond to 50% inhibition (IC50) of two bacteria, E. coli and S. aureus were tested. The bacteria were collected from surface water and wastewater at different locations of Kolkata and Howr ah. Among the fluoroquinolone antibiotics, the concentration value of ciprofloxacin has been detected in its highest contamination level, so the IC50 values of bacteria were tested against this antibiotic. While checking for the IC50 values for bacteria against ciprofloxacin, it was found that the E. coli and S. aureus isolated from wastewater and surface water were found to be 26 times and 30 times more resistance against pure E. coli and S. aureus. Along with this, bacteria present in wastewater was found to be more resistant than the bacteria found in surface water.
E. coli, S. aureus, bioassay, minimum inhibition concentration, ciprofloxacin