Potential Ecological and Human Health Impacts of Antibiotics and Antibiotic-Resistant Bacteria from Wastewater Treatment Plants

Abstract

The occurrence of antibiotics and other pharmaceuticals in the environment has become an increasing public concern as recent environmental monitoring activities reveal the presence of a broad range of persistent pharmaceuticals in soil and water. Studies show that municipal wastewater treatment plants (WWTPs) are important point sources of antibiotics and antibiotic-resistant bacteria in the environment. The fate of antibiotics and other pharmaceuticals in WWTPs is greatly influenced by the design and operation of treatment systems. Because knowledge on the fate of antibiotics and resistant bacteria in WWTPs is important in estimating their potential impacts on ecology and human health, investigations on occurrence, treatment, and observed effects are reviewed in this article. In addition, human health risk assessment protocols for antibiotic and resistant bacteria are described. Although data on other pharmaceutical compounds are also presented, discussion is focused on antibiotics in the environment because of the potential link to increased emergence of resistance among pathogenic bacteria. The applications of modern analytical methods that facilitate the identification of novel transformation products of pharmaceuticals in environmental matrices are also included to illustrate that the disappearance of the parent pharmaceuticals in WWTPs does not necessarily equate to their complete removal.

A seasonal study of the mecA gene and Staphylococcus aureus including methicillin-resistant S. aureus in a municipal wastewater treatment plant

“…β-Lactam antibiotics have been detected in wastewater systems (Brown et al, 2006), although they are not persistent in aquatic environments due to hydrolysis of the β-lactam ring (Cha et al, 2006). Previous data have shown significantly higher numbers of antibiotic-resistant bacteria in wastewater compared to the natural environment (Kim and Aga, 2007). Little is currently known about the dynamics of antibiotic-resistant bacteria and genes encoding antibiotic resistance in wastewater treatment plants (WWTPs).…”

Long-term field application of sewage sludge increases the abundance of antibiotic resistance genes in soil

“…ARGs have been detected at all stages of the municipal wastewater treatment process (Lachmayr et al, 2009;Munir et al, 2011), and the vast majority of ARGs are discharged from the municipal wastewater treatment process together with sewage sludge (Bondarczuk et al, 2016). Land application is one of the key management approaches of sewage sludge from wastewater treatment plants (Kim and Aga, 2007). This practice is cost effective with added benefits from its residual nutrients (Candela et al, 2007), but it also represents a major pathway of ARGs spread onto farmlands (Chen and Zhang, 2013).…”

Wastewater as a point source of antibiotic-resistance genes in the sediment of a freshwater lake

“…Moreover, various studies have demonstrated that wastewater and animal waste contain large numbers of resistant bacteria, which can pass through the wastewater treatment plant (WWTP) and reach the receiving water bodies (Teuber, 2001;Kü mmerer, 2004;Jury et al, 2011;Rizzo et al, 2013;Zurfluh et al, 2013). There is growing concern that continuous discharge of these contaminants may, at least locally, lead to an increase in the natural resistance background levels and thus enhance the likelihood of antibiotic-resistance genes (ARGs) being transferred back to human and animal commensals or even pathogens (Kim and Aga, 2007;Martinez, 2009b;Cantas et al, 2013). In the long term, this 'environmental loop' could contribute to the spread of resistance in pathogens and undermine the effectiveness of current and future antibiotics.…”