摘要：The objective of this study was to monitor changes (amplification or attenuation) in antibiotic resistance during wastewater treatment based on the ecology of tetracycline-resistant bacteria. The untreated and treated wastewater were collected in four seasons. Number of tetracycline-(TET R ) and oxytetracycline-resistant (OTC R ) bacteria, their qualitative composition, minimum inhibitory concentrations (MICs), sensitivity to other antibiotics, and the presence of tet (A, B, C, D, E) resistance genes were determined. TET R and OTC R counts in untreated wastewater were 100 to 1000 higher than in treated effluent. OTC R bacterial counts were higher than TET R populations in both untreated and treated wastewater. TET R isolates were not dominated by a single bacterial genus or species, whereas Aeromonas hydrophila and Aeromonas sobria were the most common in OTC R isolates. The treatment process attenuated the drug resistance of TET R bacteria and amplified the resistance of OTC R bacteria. In both microbial groups, the frequency of tet (A) gene increased in effluent in comparison with untreated wastewater. Our results also indicate that treated wastewater is a reservoir of multiple drug-resistant bacteria as well as resistance determinants which may pose a health hazard for humans and animals when released to the natural environment.
