title: Inhibition of biofilm maturation by linezolid in meticillin-resistant Staphylococcus epidermidis clinical isolates: comparison with other drugs.
abstract: Biofilm resistance mechanisms are multifactorial and vary from one organism to another. The purpose of this study was to investigate the efficacy of linezolid against indwelling device-related meticillin-resistant Staphylococcus epidermidis (MRSE) biofilm, and compare this with other antimicrobials. MICs, minimum biofilm inhibitory concentrations (MBICs) and minimum biofilm eradication concentrations (MBECs) were determined by the microtitre plate method. Fourteen and thirteen isolates from patients with indwelling device-related bacteraemia (IDB) and indwelling device colonization not associated with bacteraemia, respectively, were assessed. High MBIC was associated with a high intensity of biofilm formation (gentamicin r=0.796; linezolid r=0.477; rifampicin r=0.634; tigecycline r=0.410; and vancomycin r=0.771), but this correlation was not observed with MBEC. Linezolid demonstrated better in vitro antimicrobial activity than other antimicrobials (MBIC - gentamicin P<0.001, rifampicin P=0.019, vancomycin P=0.008; MBEC - gentamicin P<0.001, rifampicin P=0.002, vancomycin P<0.001). Biofilm growth inhibition was strongly associated with biofilm formation intensity; however, biofilm eradication was not cell number dependent. MRSE biofilm eradication would represent a huge advance for IDB, although high concentrations of gentamicin, linezolid, rifampicin, tigecycline and vancomycin were required for that. In general, linezolid reached better in vitro concentrations and was demonstrated to be highly active against MRSE biofilms by inhibiting their growth during biofilm formation.
authors.affiliation: Laboratory of Gram-positive Cocci, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.|Health Sciences Post-graduate Program, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.
authors.forename: Keli Cristine
authors.initials: KC
authors.lastname: Reiter
authors.affiliation: Laboratory of Gram-positive Cocci, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.
authors.forename: Bárbara
authors.initials: B
authors.lastname: Villa
authors.affiliation: Laboratory of Gram-positive Cocci, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.|Health Sciences Post-graduate Program, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.
authors.forename: Thiago Galvão da Silva
authors.initials: TGDS
authors.lastname: Paim
authors.affiliation: Laboratory of Gram-positive Cocci, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.|Health Sciences Post-graduate Program, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.
authors.forename: Caio Fernando
authors.initials: CF
authors.lastname: de Oliveira
authors.affiliation: Laboratory of Gram-positive Cocci, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.|Health Sciences Post-graduate Program, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil.
authors.forename: Pedro Alves
authors.initials: PA
authors.lastname: d'Azevedo
mesh_terms: D000081:Acetamides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016470:Bacteremia / Q000382:microbiology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001431:Bacteriological Techniques; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D015964:Gene Expression Regulation, Bacterial; D000069349:Linezolid; D008712:Methicillin / Q000494:pharmacology; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D023303:Oxazolidinones / Q000494:pharmacology*; D016459:Prosthesis-Related Infections / Q000382:microbiology; D013203:Staphylococcal Infections / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000187:drug effects / Q000502:physiology*
chemical_list: D000081:Acetamides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D023303:Oxazolidinones; D000069349:Linezolid; D008712:Methicillin