Editor: Ewa Sadowy
Increased tolerance of Staphylococcus aureus to vancomycin in viscous media
Article first published online: 29 AUG 2007
FEMS Immunology & Medical Microbiology
Volume 51, Issue 2, pages 277–288, November 2007
How to Cite
Kostenko, V., Ceri, H. and Martinuzzi, R. J. (2007), Increased tolerance of Staphylococcus aureus to vancomycin in viscous media. FEMS Immunology & Medical Microbiology, 51: 277–288. doi: 10.1111/j.1574-695X.2007.00300.x
- Issue published online: 29 AUG 2007
- Article first published online: 29 AUG 2007
- Received 14 February 2007; revised 25 May 2007; accepted 19 June 2007.First published online October 2007.
- Staphylococcus aureus;
- antimicrobial susceptibility;
- medium viscosity;
The increased viscosity observed in biofilms, adherent communities of bacterial cells embedded in a polymeric matrix, was hypothesized to induce increased tolerance of bacteria to antibiotics. To test this concept, planktonic Staphylococcus aureus cells were grown and exposed to vancomycin in media brought to specific viscosities in order to mimic the biofilm extracellular polymeric matrix. A viscous environment was observed to decrease the vancomycin susceptibility of planktonic S. aureus to levels seen for biofilms. Both planktonic S. aureus at a viscosity of 100 mPa s and staphylococcal biofilms were able to survive at >500 times the levels of the antibiotic effective against planktonic populations in standard medium. Time-dependent and dose-dependent viability curves revealed that more than one mechanism was involved in high S. aureus tolerance to vancomycin in viscous media. Increased viscosity affects antibiotic susceptibility by reducing diffusion and the mass transfer rate; this mechanism alone, however, cannot explain the increased tolerance demonstrated by S. aureus in viscous media, suggesting that viscosity may also alter the phenotype of the planktonic bacteria to one more resistant to antimicrobials, as seen in biofilms. However, these latter changes are not yet understood and will require further study.