title: Subinhibitory concentrations of beta-lactams and other cell-wall antibiotics inhibit listeriolysin production by Listeria monocytogenes.
abstract: In the present study we tested the ability of beta-lactam antibiotics and other cell-wall antibiotics to inhibit the production of listeriolysin which is the main virulence factor of L. monocytogenes. The amount of listeriolysin produced was measured in the supernatants with a sensitive hemolysin assay and as beta-galactosidase expression from the listeriolysin promoter. When tested in concentrations that did not affect growth of the bacteria, all beta-lactam antibiotics and all other cell-wall antibiotics tested were able to reduce the listeriolysin production in at least one of the tests used. Yet, no change in beta-galactosidase activity was detected in a strain harboring a control beta-galactosidase fusion. We therefore demonstrate for the first time that subinhibitory concentrations of antibiotics specifically reduce the production of a virulence factor of L. monocytogenes.
authors.affiliation: Institute of Medical Microbiology and Hygiene Mannheim, Faculty of Clinical Medicine, University of Heidelberg, 68167 Mannheim, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Nichterlein
authors.forename: E
authors.initials: E
authors.lastname: Domann
authors.forename: M
authors.initials: M
authors.lastname: Kretschmar
authors.forename: M
authors.initials: M
authors.lastname: Bauer
authors.forename: A
authors.initials: A
authors.lastname: Hlawatsch
authors.forename: H
authors.initials: H
authors.lastname: Hof
authors.forename: T
authors.initials: T
authors.lastname: Chakraborty