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

J M Talia, M A Alvarez, N B Debattista, N B Pappano

Laboratory of Physical Chemistry, Department of Chemistry, San Luis National University, San Luis, Argentina.

Folia microbiologica 2009 Nov

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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 microg/mL, while combinations of 2-8 microg/mL OXC with 10 microg/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.

Citation

J M Talia, M A Alvarez, N B Debattista, N B Pappano. Susceptibility of Staphylococcus aureus strains toward combinations of oxacillin-2,4-dihydroxychalcone. Folia microbiologica. 2009 Nov;54(6):516-20