Role of antibiotic residues in development of antibiotic resistance in coastal bacterial communities

Antibiotics are becoming pollutants in water bodies due to inadequate wastewater treatment, inappropriate dumping, and runoff from agriculture and other pathways. The growth of bacteria resistant to antibiotics are promoted through contamination, endangering both human health and marine aquatic life. Antibiotic resistance in water sources has emerged as a significant environmental and public health concern. Antibiotic-resistant bacteria use the aquatic environment as a reservoir, which contributes significantly to the spread of antibiotic resistance due to its ability to collect, amplify, and disseminate resistant bacteria. The Gulf of Khambhat, located in the western part of India, a vital marine ecosystem, faces increasing antibiotic contamination from industrial discharges, agricultural runoff, and aquaculture effluents. This study aims to examine the presence of antibiotic residues and their impact on bacterial resistance in marine waters. Using LC-MS, six antibiotics (Ampicillin, Cefadroxil, Ceftazidime, Nitrofurantoin, Norfloxacin, and Penicillin G) were detected across multiple sites. Bacterial resistance profiling, conducted via the disc diffusion method and the ABCD kit, revealed widespread multidrug resistance, even in areas with undetectable residues, suggesting horizontal gene transfer and co-selection with pollutants. Statistical analysis linked antibiotic resistance with elevated biological oxygen demand (BOD), nitrate levels, and total dissolved solids (TDS), indicating pollution-driven selection pressures. Given the Gulf’s ecological and economic significance, these findings highlight the urgent need for stricter wastewater management and pollution control to curb the spread of antibiotic-resistant bacteria in marine environments.