title: Differential roles of RND efflux pumps in antimicrobial drug resistance of sessile and planktonic Burkholderia cenocepacia cells.
abstract: Burkholderia cenocepacia is notorious for causing respiratory tract infections in people with cystic fibrosis. Infections with this organism are particularly difficult to treat due to its high level of intrinsic resistance to most antibiotics. Multidrug resistance in B. cenocepacia can be ascribed to different mechanisms, including the activity of efflux pumps and biofilm formation. In the present study, the effects of deletion of the 16 operons encoding resistance-nodulation-cell division (RND)-type efflux pumps in B. cenocepacia strain J2315 were investigated by determining the MICs of various antibiotics and by investigating the antibiofilm effect of these antibiotics. Finally, the expression levels of selected RND genes in treated and untreated cultures were investigated using reverse transcriptase quantitative PCR (RT-qPCR). Our data indicate that the RND-3 and RND-4 efflux pumps are important for resistance to various antimicrobial drugs (including tobramycin and ciprofloxacin) in planktonic B. cenocepacia J2315 populations, while the RND-3, RND-8, and RND-9 efflux systems protect biofilm-grown cells against tobramycin. The RND-8 and RND-9 efflux pumps are not involved in ciprofloxacin resistance. Results from the RT-qPCR experiments on the wild-type strain B. cenocepacia J2315 suggest that there is little regulation at the level of mRNA expression for these efflux pumps under the conditions tested.
authors.affiliation: Dipartimento di Biologia e Biotecnologie L. Spallanzani, Università degli Studi di Pavia, Pavia, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Buroni
authors.affiliation: Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium.
authors.forename: Nele
authors.initials: N
authors.lastname: Matthijs
authors.affiliation: Dipartimento di Biologia e Biotecnologie L. Spallanzani, Università degli Studi di Pavia, Pavia, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Spadaro
authors.affiliation: Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium.
authors.forename: Heleen
authors.initials: H
authors.lastname: Van Acker
authors.affiliation: Dipartimento di Biologia e Biotecnologie L. Spallanzani, Università degli Studi di Pavia, Pavia, Italy.
authors.forename: Viola C
authors.initials: VC
authors.lastname: Scoffone
authors.affiliation: Dipartimento di Biologia e Biotecnologie L. Spallanzani, Università degli Studi di Pavia, Pavia, Italy.
authors.forename: Maria Rosalia
authors.initials: MR
authors.lastname: Pasca
authors.affiliation: Dipartimento di Biologia e Biotecnologie L. Spallanzani, Università degli Studi di Pavia, Pavia, Italy.
authors.forename: Giovanna
authors.initials: G
authors.lastname: Riccardi
authors.affiliation: Laboratory of Pharmaceutical Microbiology, Ghent University, Ghent, Belgium tom.coenye@ugent.be.
authors.forename: Tom
authors.initials: T
authors.lastname: Coenye
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D057508:Burkholderia cenocepacia / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D002939:Ciprofloxacin / Q000494:pharmacology; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D019450:Genes, MDR; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009876:Operon; D010933:Plankton / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D014031:Tobramycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D002939:Ciprofloxacin; D014031:Tobramycin