title: Monitoring and evaluation of antibiotic-resistant bacteria at a municipal wastewater treatment plant in China.
abstract: The prevalence of antibiotic-resistant bacteria in municipal wastewater treatment plants (WWTPs) is becoming a concern of public health. In order to acquire information on the emission of antibiotic-resistant bacteria from WWTP effluents into natural waters, both average antibiotic tolerance and concentrations of antibiotic-resistant bacteria in the effluent of a WWTP in Beijing, China were investigated. A new index of IC(50)/MIC ratio (the antibiotic concentration required to inhibit 50% of total heterotrophic bacteria compared to the highest minimum inhibitory concentration value of a group of pathogens according to a specific antibiotic, as defined by CLSI) was used to reflect the average antibiotic tolerance of total heterotrophic bacteria in the secondary effluent. The results showed that the IC(50)/MIC ratios of heterotrophic bacteria in the secondary effluent to penicillin, ampicillin, cephalothin, chloramphenicol and rifampicin were >2, >1, >1, and 1.08, respectively, which reflected a significantly high general level of heterotrophic bacteria found in the secondary effluent resistant to these five antibiotics. The concentrations of penicillin-, ampicillin-, cephalothin-, and chloramphenicol-resistant bacteria were as high as 1.5×10(4)-1.9×10(5), 1.2×10(4)-1.5×10(5), 8.9×10(3)-1.9×10(5) and 2.6×10(4)-2.0×10(5) CFU/mL, and the average percentages in relation to total heterotrophic bacteria were 63%, 47%, 55%, and 69%, respectively. The concentrations of tetracycline- and rifampicin-resistant bacteria were 840-6.1×10(3) and 310-6.1×10(4) CFU/mL with average percentages of 2.6% and 11%, respectively. Furthermore, our study found that five- and six-antibiotic-resistant bacteria were widely distributed in four types of enterobacteria from the secondary effluent. The presence of multiple-antibiotic-resistant bacteria from effluents of WWTPs into natural waters could pose a serious problem as a secondary pollutant of drinking water.
authors: State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China.
authors: Jing-Jing
authors: JJ
authors: Huang
authors: Hong-Ying
authors: HY
authors: Hu
authors: Sun-Qin
authors: SQ
authors: Lu
authors: Yi
authors: Y
authors: Li
authors: Fang
authors: F
authors: Tang
authors: Yun
authors: Y
authors: Lu
authors: Bin
authors: B
authors: Wei
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000145:classification / Q000187:drug effects / Q000254:growth & development*; D002681:China; D024881:Drug Resistance, Bacterial; D004755:Enterobacteriaceae / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification; D004784:Environmental Monitoring; D008826:Microbial Sensitivity Tests; D011634:Public Health; D012722:Sewage / Q000382:microbiology; D013752:Tetracycline / Q000494:pharmacology; D014865:Waste Disposal, Fluid; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods
chemical_list: D000900:Anti-Bacterial Agents; D012722:Sewage; D013752:Tetracycline