Water contamination by commonly used antimicrobials around a tertiary care centre in South Kerala, India – environmental risk and antimicrobial resistance perspective

Water contamination due to pharmaceuticals is a serious health concern and antimicrobials in particular pose a major challenge pertaining to the development of antimicrobial resistance. The level of water contamination caused by antimicrobials in water sources and its consequences such as environmental risk and antimicrobial resistance is less explored in Kerala, India. The study aims to find the concentration of antimicrobials in water sources and to analyze the environmental risk and antimicrobial resistance that can arise due to the prevailing drug concentration in water sources. Five commonly used antimicrobials in a tertiary care centre were identified with the help of case records and purchase records for a period of one year- Azithromycin, Cefotaxime, Ciprofloxacin, Meropenem and Metronidazole Thirty-one samples of surface and ground water including drinking water sources collected were preconditioned by solid phase extraction technique and passed through Liquid Chromatography Mass Spectrometry (LCMS-MS) instrument to quantify the concentrations of antimicrobials. Measured median environmental concentration (MEC) were- Azithromycin (0.60 µg/L), Cefotaxime (1.0 µg/L), Ciprofloxacin (0.07 µg/L), Meropenem (0.05 µg/L and Metronidazole (1.73 µg/L). Using Predicted no effect concentration- environment (PNEC-ENV), environmental risk (R) calculated for Azithromycin (97.67), Cefotaxime (25.83), Ciprofloxacin (1.76), Meropenem (2.28) and Metronidazole (78.0) are above the value of 1, which shows that they are at a level to cause environmental risk. Highest MECs of the five antibiotics against PNEC-MIC (minimum inhibitory concentration) – Azithromycin (2.93, 0.25), Cefotaxime (3.10, 0.13), Ciprofloxacin (0.80, 0.06), Meropenem (3.42, 0.06) and Metronidazole (2.35, 0.13) shows that MECs are above the PNEC- MIC values used for determining antimicrobial resistance. These points to the occurrence of grave consequence of selection of antimicrobial resistant organisms in the environment. The concentration of antimicrobials in the water sources are in the range of posing environmental risk and for selection of antimicrobial resistant organisms in the environment. Water purification methods have to be developed to remove these drugs from water sources. Modification of policy regulations for proper and safe disposal of drugs have to be done and implemented to prevent pharmaceuticals from entering the water sources.