Antibiotic resistance of bacteria to 6 antibiotics in secondary effluents of municipal wastewater treatment plants

College of Environmental Science and Engineering, Hohai University, Nanjing 210098, China.
Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.] 11/2011; 32(11):3419-24.
Source: PubMed


Prevalence of antibiotic-resistant bacteria in wastewater effluents is concerned as an emerging contaminant. To estimate antibiotic resistance in secondary effluents of municipal wastewater treatment plants, antibiotic tolerance of heterotrophic bacteria, proportion of antibiotic-resistant bacteria and hemi-inhibitory concentrations of six antibiotics (penicillin, ampicillin, cefalexin, chloramphenicol, tetracycline and rifampicin) were determined at two wastewater treatment plants (WWTPs) in Beijing. The results showed that proportions of ampicillin-resistant bacteria in WWTP-G and chloramphenicol-resistant bacteria in WWTP-Q were highest to 59% and 44%, respectively. The concentrations of ampicillin-resistant bacteria in the effluents of WWTP-G and WWTP-Q were as high as 4.0 x 10(3) CFU x mL(-1) and 3.5 x 10(4) CFU x mL(-1), respectively; the concentrations of chloramphenicol-resistant bacteria were 4.9 x 10(2) CFU x mL(-1) and 4.6 x 10(4) CFU x mL(-1), respectively. The data also indicated that the hemi-inhibitory concentrations of heterotrophic bacteria to 6 antibiotics were much higher than common concentrations of antibiotics in sewages, which suggested that antibiotic-resistant bacteria could exist over a long period in the effluents with low concentrations of antibiotics. Antibiotic-resistant bacteria could be a potential microbial risk during sewage effluent reuse or emission into environmental waters.

Download full-text


Available from: Hong-Ying Hu, May 16, 2014
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chloramphenicol is considered a prototypical broad band spectrum antibiotic, alongside the tetracyclines, and finds extensive applications in pharmaceuticals. Hence, its oxidation kinetic study is of much significance in understanding the mechanistic profile in biological systems. In this regard, a systematic study of oxidation of chloramphenicol (CHP) by diperiodatocuprate(III) (DPC) in the presence of micro amounts (10–8 mol/dm3) of Pd(II) and Os(VIII) catalysts has been investigated spectrophotometrically in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm–3. The reaction between CHP and DPC in alkaline medium exhibits 1:2 stoichiometry in both catalyzed reactions (CHP:DPC). The oxidation products in both reactions were found to be the same and were identified and confirmed by IR, GC-MS, and 1H NMR. The order with respect to DPC concentration was unity, while the order with respect to CHP concentration varied from first order to zero order as the concentration of CHP increased. The rates increased with increase in [OH–] and decreased with increase in [IO4–]. The order with respect to [Pd(II)] and [Os(VIII)] was unity. It is observed that the catalytic efficiency for the title reaction is in the order of Pd(II) > Os(VIII). The catalytic constant was also determined at different temperatures for both reactions. The proposed mechanisms and the derived rate laws are in concurrence with the observed kinetics. The activation parameters with respect to the limiting step of the mechanism were calculated, and the thermodynamic quantities were also determined. Kinetic experiments suggest that [Cu(H2IO6)(H2O)2], [Pd(OH)2Cl2]2–, and [OsO4(OH)2]2– are the reactive oxidizing species of Cu(III), Pd(II), and Os(VIII).
    No preview · Article · Jun 2013 · Industrial & Engineering Chemistry Research