title: Morphological changes and differentially expressed efflux pump genes in Mycobacterium tuberculosis exposed to a rifampicin and verapamil combination.
abstract: The aim of the present study was to (i) evaluate the in vitro action of rifampicin (RIF), ethambutol or isoniazid with efflux pumps inhibitors (EPIs) in Mycobacterium tuberculosis (Mtb) H37Rv and (ii) evaluate the morphological and efflux pumps (EPs) transcriptional changes by the action of rifampicin + verapamil combination (RIF + VP). The minimal inhibitory concentration and synergic effect of drug combinations were determined by Resazurin Microtiter Plate Assay and Resazurin Drugs Combination Microtiter Assay, respectively. VP showed greater capacity of ethidium bromide accumulation and RIF + VP had the lower fractional inhibitory concentration index. The RIF + VP exerted a similar reduction of viable cell counts to RIF by time-kill curve, but decreases in the expression of EPs genes were observed by Real time PCR at 72 h of RIF + VP exposure. Accumulative morphological changes (wrinkled and rounding) caused by each drug were observed by scanning electron microscopy after RIF + VP exposure. The downexpression of EPs related genes exposed to RIF + VP, suggest an effective inhibitory activity of VP in Mtb H37Rv. The role of EPs and the use of EPIs open up a powerful approach and the RIF + VP combination should be studied in Mtb more thoroughly.
authors.affiliation: Postgraduate Program in Health Science, State University of Maringa, Parana, Brazil; Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Parana, Brazil.
authors.forename: Katiany R
authors.initials: KR
authors.lastname: Caleffi-Ferracioli
authors.affiliation: Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Parana, Brazil.
authors.forename: Renata Claro R
authors.initials: RC
authors.lastname: Amaral
authors.affiliation: Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Parana, Brazil.
authors.forename: Fernanda O
authors.initials: FO
authors.lastname: Demitto
authors.affiliation: Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Parana, Brazil.
authors.forename: Flaviane G
authors.initials: FG
authors.lastname: Maltempe
authors.affiliation: Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Parana, Brazil.
authors.forename: Pedro Henrique
authors.initials: PH
authors.lastname: Canezin
authors.affiliation: Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Parana, Brazil.
authors.forename: Regiane B L
authors.initials: RB
authors.lastname: Scodro
authors.affiliation: Department of Basic Health Sciences, State University of Maringa, Parana, Brazil.
authors.forename: Celso V
authors.initials: CV
authors.lastname: Nakamura
authors.affiliation: School of Pharmaceutical Sciences, Department of Biological Sciences, Paulista State University, Araraquara, Sao Paulo, Brazil.
authors.forename: Clarice Queico F
authors.initials: CQ
authors.lastname: Leite
authors.affiliation: Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Parana, Brazil.
authors.forename: Vera Lúcia D
authors.initials: VL
authors.lastname: Siqueira
authors.affiliation: Postgraduate Program in Health Science, State University of Maringa, Parana, Brazil; Laboratory of Medical Bacteriology, Department of Clinical Analysis and Biomedicine, State University of Maringa, Parana, Brazil. Electronic address: rfressatticardoso@gmail.com.
authors.forename: Rosilene F
authors.initials: RF
authors.lastname: Cardoso
mesh_terms: D000904:Antibiotics, Antitubercular / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D026901:Membrane Transport Proteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D050296:Microbial Viability; D008855:Microscopy, Electron, Scanning; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D012293:Rifampin / Q000494:pharmacology*; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014700:Verapamil / Q000494:pharmacology*
chemical_list: D000904:Antibiotics, Antitubercular; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D014700:Verapamil; D012293:Rifampin
keywords: Drug combinations; Efflux pump; Gene expression; Morphological changes; Mycobacterium tuberculosis