title: Combined effect of linezolid and N-acetylcysteine against Staphylococcus epidermidis biofilms.
abstract: BACKGROUND
  Staphylococcus epidermidis is an organism commonly associated with infections caused by biofilms. Biofilms are less sensible to antibiotics and therefore are more difficult to eradicate. Linezolid and N-acetylcysteine (NAC), have demonstrated to be active against gram-positive microorganisms. Therefore and since linezolid and NAC have different modes of action, the main objective of this work was to investigate the single and synergistic effect of linezolid and NAC against S. epidermidis biofilms.
  
  
  METHODS
  This work reports the in vitro effect of linezolid and NAC against S. epidermidis biofilms, treated with MIC (4mgml(-1)) and 10×MIC of NAC, and MIC (1μgml(-1)) and peak serum concentration (PS=18μgml(-1)) of linezolid alone and in combination. After exposure of S. epidermidis biofilms to linezolid and/or NAC for 24h, several biofilm parameters were evaluated, namely the number of cultivable cells [colony forming unit (CFU) enumeration], total biofilm biomass and cellular activity.
  
  
  RESULTS
  When tested alone, NAC at 10×MIC was the most effective agent against S. epidermidis biofilms. However, the combination linezolid (MIC)+NAC (10×MIC) showed a synergistic effect and was the most biocidal treatment tested, promoting a 5log reduction in the number of biofilm viable cells.
  
  
  CONCLUSIONS
  This combination seems to be a potential candidate to combat infections caused by S. epidermidis biofilms, namely as a catheter lock solution therapy.
authors: IBB - Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, University of Minho, Braga, Portugal; Department of Biotechnology, Federal University of São Carlos, São Carlos, São Paulo, Brazil.
authors: Bruna
authors: B
authors: Leite
authors: Fernanda
authors: F
authors: Gomes
authors: Pilar
authors: P
authors: Teixeira
authors: Clovis
authors: C
authors: Souza
authors: Elisabeth
authors: E
authors: Pizzolitto
authors: Rosário
authors: R
authors: Oliveira
mesh_terms: D000081:Acetamides / Q000494:pharmacology*; D000111:Acetylcysteine / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D004359:Drug Therapy, Combination; D006801:Humans; D000069349:Linezolid; D008826:Microbial Sensitivity Tests; D023303:Oxazolidinones / Q000494:pharmacology*; D013212:Staphylococcus epidermidis / Q000187:drug effects*
chemical_list: D000081:Acetamides; D000890:Anti-Infective Agents; D023303:Oxazolidinones; D000069349:Linezolid; D000111:Acetylcysteine
keywords: Agentes antimicrobianos; Antimicrobial agents; Biofilm; Linezolid; N-acetilcisteína; N-acetylcysteine; Staphylococcus epidermidis