title: Effects of antibiotics on biofilm and unattached cells of a clinical Staphylococcus aureus isolate from bone and joint infection.
abstract: Treatment of orthopaedic infections remains challenging owing to the inability of antibiotics to eradicate biofilms and prevent their regrowth. The present study characterized the effects of 12 antibiotics on in vitro biofilm formed by a representative strain of meticillin-susceptible Staphylococcus aureus (MSSA) isolated from a bone infection. Determination of the minimum biofilm eradication concentrations indicated that in vitro eradication of 24 h-old biofilms required concentrations up to 51,200 times higher than MICs. The influence of the same panel of antibiotics was also investigated on biofilm formation at concentrations including the breakpoints, by numbering viable cells in the suspensions (individual cells) and the biofilm biomass. Except for fusidic acid, the presence of antibiotics during the initial steps of biofilm formation resulted in significant decreases in the number of sessile viable bacteria at the highest concentrations tested. Ceftarolin, daptomycin, fosfomycin, gentamicin, ofloxacin, rifampicin and vancomycin were the most effective drugs. Confocal microscopy analysis indicated that daptomycin was more efficient at bacteria lysis than gentamicin and vancomycin. However, viable individual cells were still detectable in the assays performed with ceftarolin, fosfomycin, ofloxacin, rifampicin and vancomycin at concentrations for which no sessile cells were detected. Although none of the molecules tested was effective at classical therapeutic concentrations against 24 h-old MSSA biofilms, all except fusidic acid were able to impair biofilm formation at concentrations near the breakpoints. However, presence of viable individual unattached cells could imply a significant risk of microbial dissemination and increased risk of infections.
authors: bioMérieux SA, 38390 La Balme-les-Grottes, France.|Laboratoire Microorganismes: Génome et Environnement, UMR CNRS 6023, Université d'Auvergne, 63000 Clermont-Ferrand, France.
authors: Claire
authors: C
authors: Marquès
authors: Department of Clinical Microbiology, Hospices Civils de Lyon, Lyon, France.|INSERM U1111, International Center for Research in Infectiology, University of Lyon 1, UMR CNRS 5308, Lyon, France.
authors: Jason
authors: J
authors: Tasse
authors: Laboratoire Microorganismes: Génome et Environnement, UMR CNRS 6023, Université d'Auvergne, 63000 Clermont-Ferrand, France.
authors: Anne
authors: A
authors: Pracros
authors: bioMérieux SA, 38390 La Balme-les-Grottes, France.
authors: Valérie
authors: V
authors: Collin
authors: bioMérieux SA, 38390 La Balme-les-Grottes, France.
authors: Christine
authors: C
authors: Franceschi
authors: Department of Clinical Microbiology, Hospices Civils de Lyon, Lyon, France.|INSERM U1111, International Center for Research in Infectiology, University of Lyon 1, UMR CNRS 5308, Lyon, France.
authors: Frédéric
authors: F
authors: Laurent
authors: bioMérieux SA, 38390 La Balme-les-Grottes, France.
authors: Sonia
authors: S
authors: Chatellier
authors: Laboratoire Microorganismes: Génome et Environnement, UMR CNRS 6023, Université d'Auvergne, 63000 Clermont-Ferrand, France.
authors: Christiane
authors: C
authors: Forestier
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D006801:Humans; D007592:Joint Diseases / Q000188:drug therapy / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D010019:Osteomyelitis / Q000188:drug therapy / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology
chemical_list: D000900:Anti-Bacterial Agents