Antibiotic resistance is one of the major problems in the medical world, and the sewage waters are the primary habitats to harbour antibiotic resistance bacteria (ARB) especially multi-drug resistance (MDR) human enteric pathogens. The present study dealt with isolation, identification and characterization of human enteric pathogens showing resistance against ten different commonly prescribed antibiotics. These bacterial strains were isolated from different sewage treatment plants located in the suburb of Delhi. Initially, samples were analysed for the presence of pathogenic human enteric bacteria through morphological, biochemical and molecular analysis. Further susceptibility patterns of these isolates were studied towards clinically significant antibiotics. Doxycycline and Metronidazole were found to be most inert antibiotic as it was ineffective against all isolated enteric pathogens, whereas Meropenem was found to be most promising antibiotic. As the resistance of these microorganisms is evolving day by day, proper steps should be taken to prevent it.

Antibiotics are used to treat bacterial infections in humans and animals and also act as a growth promoter for poultry. Due to incomplete metabolism, these antibiotics are excreted in the environment in their parental forms and accumulates in the aquatic ecosystem. Besides the evolution of antibiotic-resistant bacteria, these drugs can damage non-target organisms. Green algae are highly sensitive to different antibiotics. Damage in the algal population will cause imbalances in the ecosystems. Till now, the mechanisms of antibiotic toxicity towards algae have not been completely elucidated. It was observed that antibiotics mainly affected the photosynthetic machinery and decreased the carbon fixation process, finally resulting in algal growth inhibition. This present review deals with antibiotics classification, various routes of antibiotics exposure to the freshwater environment, sensitivity towards the different classes of antibiotics, possible Mode-of-Action (MOA) on algal systems, and gaps that need to be filled. Significant gaps include the unavailability of proper eco-toxicological data for antibiotics. Moreover, they exist in nature as complex mixtures, and their behavior in the ecosystem may vastly differ from the parent molecules. To improve our understanding of antibiotic responses mechanism in real-life scenarios, mixture toxicity studies may be the first step.