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- Title
Synergistic antibiotic activity against planktonic and biofilm-embedded Streptococcus agalactiae, Streptococcus pyogenes and Streptococcus oralis.
- Authors
Trampuz, Andrej; Gonzalez Moreno, Mercedes; Di Luca, Mariagrazia
- Abstract
<bold>Objectives: </bold>To determine the antimicrobial activity against streptococcal biofilm in species mostly isolated from implant-associated infections and examine the effect of enzyme treatment of biofilm on the antimicrobial activity of different antibiotics.<bold>Methods: </bold>The activities of fosfomycin, rifampicin, benzylpenicillin, daptomycin, gentamicin, levofloxacin, proteinase K and their combinations on planktonic and/or biofilm-embedded standard laboratory strains of Streptococcus agalactiae, Streptococcus pyogenes and Streptococcus oralis were investigated in vitro by standard methods and isothermal microcalorimetry.<bold>Results: </bold>MIC values obtained for the tested antimicrobials against planktonic bacteria ranged from 0.016 to 128 mg/L for the three species tested. Higher antibiotic concentrations were usually required to reduce biofilm in comparison with planktonic bacteria, with the exception of gentamicin, for which similar concentrations (4-16 mg/L) exerted an effect on both planktonic and biofilm cells. A synergistic effect against the streptococcal biofilm of the three species was observed when gentamicin was combined with benzylpenicillin or with rifampicin. Moreover, antibiotic concentrations comparable to the MIC observed against planktonic cells induced a strong reduction of viable bacteria in proteinase K pre-treated biofilm.<bold>Conclusions: </bold>This study shows that the combination of gentamicin with either benzylpenicillin or rifampicin exerts a synergistic effect against biofilms produced by the tested streptococci strains in vitro. Our results also suggest that coupling a dispersal agent with conventional antibiotics may facilitate their access to the bacteria within the biofilm. In vivo and clinical studies are needed in order to confirm whether such a strategy may be effective in the treatment of implant-associated infections caused by streptococci.
- Subjects
PLANKTON; BIOFILMS; STREPTOCOCCUS agalactiae; STREPTOCOCCUS pyogenes; ANTI-infective agents; ACIDS; ANTIBIOTICS; CALORIMETRY; GENTAMICIN; MICROBIAL sensitivity tests; PEPTIDE antibiotics; STREPTOCOCCAL diseases; PHARMACODYNAMICS; STREPTOCOCCUS; PHYSIOLOGY
- Publication
Journal of Antimicrobial Chemotherapy (JAC), 2017, Vol 72, Issue 11, p3085
- ISSN
0305-7453
- Publication type
journal article
- DOI
10.1093/jac/dkx265