Antibiotic resistance plasmids in wastewater treatment plants and their possible dissemination into the environment

Antibiotic resistance plasmids found in wastewater treatment plants (WWTPs) may represent a threat to public health if they are readily disseminated into the environment and ultimately into pathogenic bacteria. The wastewater environments provide an ideal ecosystem for development and evolution of antibiotic resistance plasmids. Selective pressures for resistance to toxic compounds, high organic content and high bacterial diversity promotes gene exchange mechanisms involving interactions of conjugative plasmids with bacterial chromosomes, integrons and transposons resulting in the acquisition and accumulation of various antibiotic resistance genes into plasmids. Several studies have isolated plasmids from wastewater plants which carry resistance genes to almost all clinically relevant antibiotics. This review will discuss the possible release of these plasmids from WWTPs and their undesirable effects in the environment. Studies using advanced molecular detection tools and high throughput DNA sequencing technology help accurately quantify the prevalence and transmission of these plasmids in the environment. Ultimately assessing the significance of these plasmids as pollutants will help to determine the implications to public health.