title: Antimicrobial resistance in Enterococcus spp. isolated in inflow, effluent and sludge from municipal sewage water treatment plants.
abstract: Antimicrobial resistance of enterococci was investigated in 42 samples of crude inflow, treated effluent and sludge collected in 14 municipal sewage treatment plants of Portugal. A total of 983 enterococci were recovered and tested, using the diffusion agar method, regarding their sensitivity to 10 different antimicrobial drugs. Multidrug resistance was present in 49.4% of the isolates. Only 3.3% and 0.6% of the investigated strains were resistant to ampicillin and vancomycin, respectively. Resistances found against rifampicin (51.5%), tetracycline (34.6%), erythromycin (24.8%) and nitrofurantoin (22.5%), are causes for substantial concern. Almost 14% of isolates were resistant to ciprofloxacin. Wastewater treatment resulted in enterococci decrease between 0.5 and 4log; nevertheless, more than 4.4 x 10(5)CFU/100ml were present in the outflow of the plants. Our data indicate that the use of antimicrobials had created a large pool of resistance genes and that sewage treatment processes are unable to avoid the dissemination of resistant enterococci into the environment.
authors.affiliation: ICBAS-Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, Largo Professor Abel Salazar, 2, 4099-003 Porto, Portugal. pmcosta@icbas.up.pt
authors.forename: Paulo
authors.initials: P
authors.lastname: Martins da Costa
authors.forename: Paulo
authors.initials: P
authors.lastname: Vaz-Pires
authors.forename: Fernando
authors.initials: F
authors.lastname: Bernardo
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004352:Drug Resistance, Microbial; D016983:Enterococcus / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D012722:Sewage / Q000382:microbiology*; D014871:Water Microbiology
chemical_list: D000900:Anti-Bacterial Agents; D012722:Sewage