Nutrient-induced antibiotic resistance in Enterococcus faecalis in the eutrophic environment.
Nutrient deposition and extensive use of antibiotics are increasing worldwide, especially in freshwater ecosystems. Bacteria display resistance to certain antibiotics and thus survive for extended periods in eutrophic environments. In this study, model ecosystems were established to investigate the effect of nitrate and phosphate nutrient salts on antibiotic resistance in strains of Enterococcus faecalis. Mesocosms were replicated to evaluate the ecological effects of nutrient influx. The mesocosms were divided into four different nitrogen (N) and phosphorus (P) regimens. Enterococcus faecalis strains were isolated on Days 0, 1, 7, 14, 21, 28, 40, 60 and 95 to evaluate their sensitivity to ampicillin, oxytetracycline (OXY), ciprofloxacin (CIP), chloramphenicol (CHL), vancomycin and erythromycin (ERY). Resistance genes for ERY (ermB, msrC and mefA), OXY [tet(M), tet(L) and tet(S)] and CHL (cat) as well as the enterococcal surface protein gene (esp) were investigated by PCR. The total nitrogen, total phosphorus, chemical oxygen demand permanganate index (CODMn), chlorophyll-a, Secchi depth and trophic level index were observed. In conclusion, addition of N and P had a significant influence on the resistance phenotypes of E. faecalis to OXY, CHL and ERY. Only high dosage led to CIP resistance. Higher total N concentrations resulted in the development of relatively higher resistance to OXY and CIP. The resistance genes tet(L) and tet(S) for OXY, msrC for ERY and cat for CHL were found to be associated with resistance in E. faecalis.
College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, PR China; Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad, Pakistan; College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou 350002, PR China.
Liaqat
L
Ali
College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, PR China.
Yan-Qiu
YQ
Wang
College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, PR China.
Jie
J
Zhang
Department of Biosciences, Faculty of Science, COMSATS Institute of Information Technology, Islamabad, Pakistan.
Muhammad
M
Ajmal
College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, PR China.
Zhengrun
Z
Xiao
College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, PR China.
Jiarong
J
Wu
College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, PR China; CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, PR China.
Ji-Long
JL
Chen
College of Animal Science, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, PR China. Electronic address: yudaojin@yeah.net.
Daojin
D
Yu
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D017753:Ecosystem; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000235:genetics; D005798:Genes, Bacterial; D008826:Microbial Sensitivity Tests; D009566:Nitrates / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D014871:Water Microbiology
D000900:Anti-Bacterial Agents; D009566:Nitrates; D010710:Phosphates
Antibiotic resistance genes; Aquatic environment; Model ecosystem; Nitrate and phosphate ions; Sediment; Trophic level index