No abstract

No 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.

No abstract

No abstract

Six antibiotic resistance genes (blaCTX-M , blaSHV , blaTEM , qnrA, qnrB and qnrS) were quantified by qPCR in both phage and bacterial DNA fractions of environmental water samples in order to determine the contribution of phages to the dissemination of antibiotic resistance genes (ARGs) in the environment. Although the highest copy numbers (p <0.05) of ARGs were detected in the bacterial DNA fraction, qnrS and blaSHV genes were found in the phage DNA from all samples analysed, reaching up to 4 log10 copy numbers/mL in hospital samples. These results indicate that bacteriophages are a potential reservoir of resistance genes and may act as efficient vehicles for horizontal gene transfer.

No abstract

No abstract