title: Impact of antibiotics on conjugational resistance gene transfer in Staphylococcus aureus in sewage.
abstract: The growing rate of microbial pathogens becoming resistant to standard antibiotics is an important threat to public health. In order to assess the role of antibiotics in the environment on the spread of resistance factors, the impact of subinhibitory concentrations of antibiotics in sewage on gene transfer was investigated using conjugative gentamicin resistance (aacA-aphD) plasmids of Staphylococcus aureus. Furthermore, the concentration of antibiotics in hospital sewage was measured by high-performance liquid chromatography (HPLC)-electrospray tandem mass spectrometry. Several antibiotics were found to be present in sewage, e.g. ciprofloxacin up to 0.051 mgl(-1) and erythromycin up to 0.027 mgl(-1). Resistance plasmid transfer occurred both on solidified (dewatered) sewage and in liquid sewage in a bioreactor with a frequency of 1.1x10(-5)-5.0x10(-8). However, low-level concentrations of antibiotics measured in sewage are below concentrations that can increase plasmid transfer frequencies of gentamicin resistance plasmids of staphylococci.
authors.affiliation: Institute for Molecular Biology of Infectious Diseases, The University of Würzburg, Röntgenring 11, D-97070 Würzburg, Germany. knut.ohlsen@mail.uni-wuerzburg.de
authors.forename: Knut
authors.initials: K
authors.lastname: Ohlsen
authors.forename: Thomas
authors.initials: T
authors.lastname: Ternes
authors.forename: Guido
authors.initials: G
authors.lastname: Werner
authors.forename: Ursula
authors.initials: U
authors.lastname: Wallner
authors.forename: Dirk
authors.initials: D
authors.lastname: Löffler
authors.forename: Wilma
authors.initials: W
authors.lastname: Ziebuhr
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Witte
authors.forename: Jörg
authors.initials: J
authors.lastname: Hacker
mesh_terms: D000900:Anti-Bacterial Agents / Q000032:analysis / Q000494:pharmacology*; D018441:Biofilms; D019149:Bioreactors; D003227:Conjugation, Genetic / Q000187:drug effects*; D024881:Drug Resistance, Bacterial / Q000235:genetics; D005839:Gentamicins / Q000494:pharmacology; D011815:R Factors; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; D012722:Sewage