Antibiotic resistance dissemination and sewage treatment plants

Antibiotics are a class of naturally-occurring and synthetic chemical compounds with antimicrobial activity and are widely used in human and veterinary medicine. The increasing incidence of resistance to a wide range of antibiotic agents by a variety of organisms is a major concern facing modern medicine. There is widespread speculation that sewage treatment plants (STPs) and aquatic environments in general maybe a breeding ground for antibiotic resistant bacteria. In this minireview, we examine and consider whether the presence of antibiotics in STPs facilitates the acquisition and proliferation of resistance characteristics amongst bacteria in that environment, or whether it just simply imparts a selective pressure for the propagation of clonal resistance. Literature reports relating to bacterial and resistance counts, upstream and downstream of hospital, pharmaceutical and town STPs in different geographical regions are appraised and inferences presented. The mini-review also appraises available literature on the acquisition of antibiotic resistance by previously nonresistant bacteria and the role of antibiotics in the transfer of resistant genes in STPs. Specific observations that would be required to confirm these phenomena are identified and experimental approaches, including culture-independent methods, are suggested.