Evaluation of antibiotic resistant lactose fermentative opportunistic pathogenic Enterobacteriaceae bacteria and blaTEM-2 gene in cephalosporin wastewater and its discharge receiving river

This study investigated the concentration of cephalosporin, the resistant levels of lactose fermentative opportunistic pathogenic Enterobacteriaceae bacteria (LFOPEB) against seven antibiotics and one cephalosporin-resistant gene in cephalosporin wastewater (CPWW) treatment plant and its discharge receiving river. Although large numbers of bacteria have been removed during the CPWW treatment process, the antibiotic resistant rates of the isolates to β-lactam antibiotics significantly increased (p = 0.032) after treatment, while the percentage of resistant LFOPEB to non-β-lactam antibiotics did not change dramatically. Furthermore, the discharge of the effluent of CPWW treatment plant (CPWW_eff) led to an obvious increase in the percentages of β-lactam antibiotic-resistant LFOPEB and relative abundance of the blaTEM-2 gene in the downstream receiving river (RW_down) in comparison with those in the upstream receiving river (RW_up). The antibiotic resistant phenotypes of isolates in the influent of CPWW treatment plant (CPWW_in), CPWW_eff and RW_down appeared to be seriously affected by the cephalosporin residues, which suggested that main antibiotic resistance phenotypes in antibiotic contaminated water were closely associated with its antibiotic composition. Therefore, CPWW treatment process has been proved to result in selective growth of ARB and proliferation of ARG. Besides, CPWW_eff was also proved to be an important supplier of ARB and ARG to the receiving river.