Quantifying Nonspecific TEM β-Lactamase ( bla _TEM ) Genes in a Wastewater Stream

Abstract

To control the antibiotic resistance epidemic, it is necessary to understand the distribution of genetic material encoding antibiotic resistance in the environment and how anthropogenic inputs, such as wastewater, affect this distribution. Approximately two-thirds of antibiotics administered to humans are ␤-lactams, for which the predominant bacterial resistance mechanism is hydrolysis by ␤-lactamases. Of the ␤-lactamases, the TEM family is of overriding significance with regard to diversity, prevalence, and distribution. This paper describes the design of DNA probes universal for all known TEM ␤-lactamase genes and the application of a quantitative PCR assay (also known as Taqman) to quantify these genes in environmental samples. The primer set was used to study whether sewage, both treated and untreated, contributes to the spread of these genes in receiving waters. It was found that while modern sewage treatment technologies reduce the concentrations of these antibiotic resistance genes, the ratio of bla TEM genes to 16S rRNA genes increases with treatment, suggesting that bacteria harboring bla TEM are more likely to survive the treatment process. Thus, ␤-lactamase genes are being introduced into the environment in significantly higher concentrations than occur naturally, creating reservoirs of increased resistance potential.

Antibiotic resistance genes in an urban river as impacted by bacterial community and physicochemical parameters

“…Among the genes found in all water samples, aadA2-03, aadA1, bla VEB , bla TEM , and qacEΔ1 were consistently detected at high abundance. Previous studies showed high numbers of bla TEM gene copies in surface water and sediments (Lachmayr et al 2009;Singh et al 2016;Bogaerts et al 2016). The TEM-β-lactamases encoded by the bla TEM gene represents one of the most clinically significant families of β-lactamases.…”

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

“…Municipal wastewater appears to be a significant reservoir of ARGs (Lachmayr et al, 2009), however, most ARGs cannot be effectively removed by wastewater treatment processes. 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).…”

Antibiotics as CECs: An Overview of the Hazards Posed by Antibiotics and Antibiotic Resistance

“…Bacteria can become resistant to antibiotics naturally through a series of mechanisms (Aminov, 2009;Davies and Davies, 2010) as well as resistance conferred by direct exposure to a number of environmental factors including temperature and heavy metals (Seiler and Berendonk, 2012), as well as antibiotics. This may increase the rate of gene mutation and enhance subsequent acquisition of genes (e.g., coding enzymes that may damage antibiotics, enzymes that allow synthesis in the presence of inhibitors, and antibiotic pumps) carried by plasmids or other mobile genetic elements that may be exchanged with both naïve and antibiotic resistant bacteria in the environment (Lachmayr et al, 2009;Uyaguari et al, 2011). Thus, while some antibiotics may increase the mutation rate and subsequently increase the chances of causing antibiotic resistance, antibiotic resistant bacteria with mutant genes do not necessarily require subsequent acquisition of other resistance genes in order to develop resistance.…”

“…This includes the presence of antibacterial agents (e.g., Triclosan and Triclocarban) from household products (hand soaps and detergents) as well as the presence of antibiotics either excreted directly by humans or disposed of down the drain in WWTP waste streams and effluent (Lachmayr et al, 2009). Bacteria can become resistant to antibiotics naturally through a series of mechanisms (Aminov, 2009;Davies and Davies, 2010) as well as resistance conferred by direct exposure to a number of environmental factors including temperature and heavy metals (Seiler and Berendonk, 2012), as well as antibiotics.…”

“…Little is known about the direct connections between WWTPs and antibiotic resistance, yet many characteristics of wastewater make it a highly suspect medium for the spread of antibiotic resistance in the environment (Lachmayr et al, 2009). This includes the presence of antibacterial agents (e.g., Triclosan and Triclocarban) from household products (hand soaps and detergents) as well as the presence of antibiotics either excreted directly by humans or disposed of down the drain in WWTP waste streams and effluent (Lachmayr et al, 2009).…”