Prevalence and Characterisation of Non-Cholerae Vibrio spp. in Final Effl uents of Wastewater Treatment Facilities in Two Districts of the Eastern Cape Province of South Africa: Implications for Public Health

Abstract

Antibiotic resistance represents a global health problem, requiring better understanding of the ecology of antibiotic resistance genes (ARGs), their selection and their spread in the environment. Antibiotics are constantly released to the environment through wastewater treatment plant (WWTP) effluents. We investigated, therefore, the effect of these discharges on the prevalence of ARGs and bacterial community composition in biofilm and sediment samples of a receiving river. We used culture-independent approaches such as quantitative PCR to determine the prevalence of eleven ARGs and 16S rRNA gene-based pyrosequencing to examine the composition of bacterial communities. Concentration of antibiotics in WWTP influent and effluent were also determined. ARGs such as qnrS, bla TEM , bla CTX- M , bla SHV , erm(B), sul(I), sul(II), tet(O) and tet(W)were detected in all biofilm and sediment samples analyzed. Moreover, we observed a significant increase in the relative abundance of ARGs in biofilm samples collected downstream of the WWTP discharge. We also found significant differences with respect to community structure and composition between upstream and downstream samples. Therefore, our results indicate that WWTP discharges may contribute to the spread of ARGs into the environment and may also impact on the bacterial communities of the receiving river.

Antibiotic Resistance Elements in Wastewater Treatment Plants: Scope and Potential Impacts

“…It should however be noted that while molecular-based methods are highly efficient for ARG detection, these methods do not enable phenotypic analysis of antibiotic resistance phenotypes, and therefore, optimally a combination of culture-based and cultureindependent methods should be applied for comprehensive evaluation of AR in WWTPs and other environments. Currently, culture-independent quantitative PCR (qPCR) is the most widely used method for determining the relative abundance of ARGs, and these have been pivotal for source tracking of ARGs in anthropogenically impacted ecosystems [51][52][53][54]. Due to time and monetary limitations, generally only a limited amount of ARGs (out of hundreds of known genes) can be screened by qPCR, and it is therefore important to select representative ARGs that are abundant in anthropogenic point sources but not in pristine environments.…”

“…The prevalence of qnrS, blaTEM, bla CTX-M, bla SHV, erm(B), sul(I), sul(II), tet(O), and tet(W) in both biofilms and sediment samples before and after effluent discharge in the Ter River in Spain was evaluated using qPCR [54]; thus, although several of the genes were detected in upstream biofilms suggesting native AR or contamination from other anthropogenic sources, a significant increase in the relative abundance of almost all of the analyzed ARGs was detected in the biofilm samples proximal to the effluent discharge. Higher relative abundance of sul(1) and sul(2) genes in sediments proximal to WWTP effluent (relative to distant sediment levels) was also detected in a study by Czekalski et al who applied qPCR to target these sulfonamide resistance genes in Vidy Bay, Lake Geneva [79].…”

Exploring the evidence base for national and regional policy interventions to combat resistance

“…Slurry from livestock farms has also been implicated. 196,197 Developing sentinel AMR surveillance and sampling systems for higher risk environmental settings would thus seem an appropriate strategy for HICs and should be considered where technically feasible and affordable in LMICs. However, no countries have established such systems systematically outside research settings.…”

Deliberations on the impact of antibiotic contamination on dissemination of antibiotic resistance genes in aquatic environments

“…The other measured ARGs (sulII, tetO and tetW) were also observed to increase in abundance from the pristine site to the anthropogenically impacted sites. Similar to Paper II, in Marti et al, 2013, ARG concentrations in a river were analysed upstream and downstream of a WWTP in Spain. While ARG levels in biofilms were observed to be slightly elevated downstream, the concentrations of ARGs in the sediment phase were observed to be about the same upstream and downstream.…”