Antibiotic Susceptibility of Staphylococcus aureus Plankton and Biofilm Forms Isolated in Implant-Associated Infection.

Comparison of activity of antibiotics against Staphylococcus aureus strains in their plankton form and in biofilms of varying maturity showed that the concentrations of antibiotics causing death of 90% S. aureus strains (MIC90) in their plankton form was 0.07-2.80 μg/ml and significantly (p<0.05) differed from MIC90 concentrations (3-245 μg/ml) for the strains in 24 and 48 h biofilms. MIC90 value was affected by the degree of biofilm maturity: microbial resistance in 48-h biofilms for all analyzed antibiotics was significantly (p<0.05) higher than in 24-h biofilms.