Staphylococcus aureus biofilm as a target for single or repeated doses of oxacillin, vancomycin, linezolid and/or lysostaphin

Due to high resistance, standard chemotherapy of biofilm-associated staphylococcal infections is ineffective and a number of alternative approaches to antimicrobial treatment have been proposed. Minimum inhibitory concentration (MIC) and biofilm inhibitory concentration (BIC) of oxacillin (Oxa), vancomycin (Van), linezolid (Lzd) and lysostaphin (Lss) as well as the possible synergistic effect of the antibiotics and lysostaphin were determined. The Lss susceptibility of Staphylococcus aureus planktonic and bio-film cultures varied and was strain-dependent. The synergistic effect of sub-BIC(Lss)+Oxa was observed for methicillin-sensitive S. aureus (MSSa) and methicillin-resistant S. aureus (MrSa), but not for heterogeneously vancomycin-resistant S. aureus (V(h)Sa) biofilm. Van with sub-BICL(Lss) was effective against M(s)Sa and MrSa biofilm, when applied in three subsequent doses. Only sub-BICL(Lss)+Lzd combination, given as three cycles therapy, was effective in disruption of all 3 (M(s)Sa, M(r)Sa, V(h)Sa) biofilms.