Antibacterial Activity ofMulinum spinosumExtracts against Slime-ProducingStaphylococcus aureusand Methicillin-ResistantStaphylococcus aureusIsolated from Nasal Carriers
Nasal carriers ofStaphylococcus aureusare important reservoirs with risk of developing endogenous infections or transmitting infections to susceptible individuals. Methicillin-resistantS. aureus(MRSA) are associated with higher rates of treatment failure. Some strains ofS. aureusproduce slime which is believed to make the microorganisms more resistant to antibiotics and host defenses. The antibacterial activity of ethyl acetate : n-hexane (EtOAc : HEX) extracts ofMulinum spinosum(5 : 95% EtOAc : HEX, 50 : 50% EtOAc : HEX, 70 : 30% EtOAc : HEX and mix 20 : 80/30 : 70% EtOAc : HEX, 50 : 50/70 : 30/100 : 0% EtOAc : HEX) were assayed against 3 slime-producingS. aureusstrains and 2 MRSA strains isolated from nasal carriers.S. aureusATCC 35556 slime-producing strain and MRSA ATCC 43300 strain were used as controls. The extracts were prepared using flash chromatography.M. spinosum5 : 95% AcOEt : HEX showed antibacterial effect against all slime-producing strains (MIC: 500 µg/mL) and the highest activity against MRSA strains (MIC: 500 to 1000 µg/mL). AllM. spinosumextracts assayed were active against slime-producingS. aureusand MRSA at doses between 500 and 4000 µg/mL. Both, slime-producingS. aureusand MRSA are highly contagious and hardly eradicated by antibiotic therapies. So, there is an increasing need to find new substances with the ability to inhibit these strains.