A comparison of the anti-Staphylococcus aureus activity of extracts from commonly used medicinal plants.

BACKGROUND: Resurgences of Staphylococcus aureus infection continue globally, with antibiotic resistance increasing dramatically, making these infections more difficult to treat. S. aureus epidemics impose public health threats, and economic burdens on health care costs worldwide, presenting challenges modern medicine struggles to control. OBJECTIVE: In order to answer today's call for effective treatments against S. aureus, we evaluated and compared various botanical extracts that have historically been suggested as useful for their antimicrobial properties against S. aureus. DESIGN: Briefly, S. aureus cultures were treated with selected botanical extracts and the minimum inhibitory concentration (MIC) determined. In addition, to obtain more quantitative measures on bacterial growth, 24-hour growth studies were done to examine the temporal activity and stability of various botanicals on bacterial replication. RESULTS: The antimicrobial activity observed for the botanical extracts used in this comparative evaluation of efficacy included both bacteriostatic and bacteriocidal activity against S. aureus. Highly effective botanicals including Salvia officinalis, Eucalyptus globulus, Coleus forskohlii, Coptis chinensis, Turnera diffusa, and Larrea tridentata exhibited MIC values ranging from 60 to 300 µg/mL and a 10(6)-fold reduction in bacterial replication. Arctostaphylos uva-ursi and Allium sativum were slightly less effective, exhibiting MIC values ranging from 90 to 400 µg/mL and a 10(5)-fold reduction, while Anemopsis californica gave MIC value of 360 µg/mL and a 10(4)-fold reduction in bacterial replication. Many botanicals, especially at lower doses, had an initial inhibitory effect followed by a recovery in bacterial replication. Such botanicals included E. globulus, C. chinensis, T. diffusa, A. californica, and Berberis vulgaris. CONCLUSIONS: Our data demonstrate that S. officinalis, E. globulus, C. forskohlii, A. uva-ursi, C. chinensis, T. diffusa, A. californica, A. sativum, and L. tridentata all show promising direct antimicrobial activity against S. aureus. For many of these botanicals, strong bacteriocidal activity was observed at higher concentrations, but even at lower concentrations, bacteriostatic activity was evident. Other botanicals including B. vulgaris, Baptisia tinctoria, and Glycyrrhiza glabra showed moderate activity against S. aureus, while Schisandra chinensis, Echinacea angustifolia, and Polygonum multiflorum were shown to be ineffective.

Spectrum of antimicrobial activity associated with ionic colloidal silver.

OBJECTIVES: Silver has historically and extensively been used as a broad-spectrum antimicrobial agent. However, the Food and Drug Administration currently does not recognize colloidal silver as a safe and effective antimicrobial agent. The goal of this study was to further evaluate the antimicrobial efficacy of colloidal silver. DESIGN: Several strains of bacteria, fungi, and viruses were grown under multicycle growth conditions in the presence or absence of ionic colloidal silver in order to assess the antimicrobial activity. RESULTS: For bacteria grown under aerobic or anaerobic conditions, significant growth inhibition was observed, although multiple treatments were typically required. For fungal cultures, the effects of ionic colloidal silver varied significantly between different genera. No viral growth inhibition was observed with any strains tested. CONCLUSIONS: The study data support ionic colloidal silver as a broad-spectrum antimicrobial agent against aerobic and anaerobic bacteria, while having a more limited and specific spectrum of activity against fungi.