Antibiotic resistance, plasmid-mediated quinolone resistance (PMQR) genes and ampC gene in two typical municipal wastewater treatment plants.
Antibiotic resistant bacteria and plasmid-mediated quinolone resistance genes and ampC gene were investigated for Escherichia coli isolates from two typical municipal wastewater treatment plants in both dry and wet seasons by using the antibiotic susceptibility test and PCR assay, respectively. The results showed that 98.4% of the isolates (1056) were found resistant to antibiotic(s) tested and 90.6% showed multiple resistances to at least three antibiotics. Tetracycline was found to have the highest resistance frequency (70.8%), followed by ampicillin (65.1%), whereas ceftazidime had the lowest resistance frequency of 9.0%. Moreover, 39.2% of the E. coli isolates were carrying plasmids. intI1 had the highest detection rate in the plasmids (38.1%), followed by qnrS, ampC, qnrB, intI2 and aac(6')-Ib-cr. The disinfection process (UV and chlorination) could significantly reduce the number of bacteria, but percentage of the resistant bacteria, resistance frequency for each antibiotic, MAR index and detection rate of the plasmid-mediated resistance genes were all found increasing in the effluents of biological units. The results of this study showed that a more frequent horizontal gene transfer occurred in the biological units. Wastewater treatment plants were an important medium for the recombination and dissemination of antibiotic resistance genes in the environment.
State Key Laboratory of Organic Geochemistry, CAS Centre for Pearl River Delta Environmental Pollution and Control Research, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China. guangguo.ying@gmail.com guang-guo.ying@gig.ac.cn.
Hao-Chang
HC
Su
Guang-Guo
GG
Ying
Liang-Ying
LY
He
You-Sheng
YS
Liu
Rui-Quan
RQ
Zhang
Ran
R
Tao
D001426:Bacterial Proteins / Q000032:analysis; D004352:Drug Resistance, Microbial / Q000235:genetics*; D005798:Genes, Bacterial; D064091:Waste Disposal Facilities; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000382:microbiology*; D014871:Water Microbiology; D001618:beta-Lactamases / Q000032:analysis
D001426:Bacterial Proteins; D062065:Wastewater; D001618:beta-Lactamases; C048795:AmpC beta-lactamases