, Volume 54, Issue 6, pp 516-520
Date: 07 Feb 2010

Susceptibility of Staphylococcus aureus strains toward combinations of oxacillin-2,4-dihydroxychalcone

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In order to determine the existence of synergism of the bacteriostatic action of flavonoids against G+ bacteria between a clinically interesting conventional antibiotic and a flavonoid, combinations of oxacillin (OXC) and 2,4-dihydroxychalcone (DCH) as enhancer were assayed against methicillin-sensitive Staphylococcus aureus ATCC 29 213 and methicillin-resistant S. aureus ATCC 43 300. Using a kinetic-turbidimetric method, growth kinetics was monitored in a broth containing variable amounts of OXC alone and combinations of variable OXC-constant DCH. The minimum inhibitory concentrations (MIC) of OXC alone and in combination with DCH were evaluated. For the 29 213 strain, OXC MIC was 25 μg/mL, while combinations of 2–8 μg/mL OXC with 10 μg/mL of DCH totally inhibited growth and showed synergism. The resistance of the 43 300 strain in the presence of OXC was verified; OXC-DCH combinations decreased bacterial growth by 35 %. DCH augments the action of OXC against methicillin-susceptible S. aureus and therefore constitutes a good bacteriostatic agent for methicillin-resistant S. aureus.