Context: With the rise of antibiotic resistance, new strategies are needed to treat minor bacterial infections so that conventional antibiotics may be reserved for more serious conditions. One herbal formula, known as the HMPE formula, is often prescribed for minor infections. It includes Hydrastis canadensis (H. canadensis), Commiphora habessinica (C. habessinica), Phytolacca americana (P. americana), and Echinacea purpurea (E. purpurea). These herbs offer promise as treatments that may inhibit bacterial growth and stimulate the immune system.
Objective: To investigate the antibacterial effects of the HMPE formula and its constituent herbs against two organisms, Staphylococcus epidermidis and Escherichia coli.
Design: The research team performed an in-vitro study.
Setting: The study occurred at the Helfgott Research Institute at the National University of Natural Medicine in Portland, OR, USA.
Intervention: The study tested HMPE and each of its ingredients alone for antibacterial properties.
Outcome measures: The outcome measure was a disc diffusion assay. Sterile paper discs were impregnated with 15 µl of E. purpurea, H. canadensis, C. habessinica , or P. americana as herbal tinctures; with the complete HMPE formula; or with 65% ethanol as the negative control, and dried at room temperature for 40 minutes. Commercially prepared 10 µg ampicillin discs were used as a positive control.
Results: H. Canadensis and, to a lesser extent, the complete HMPE formula significantly inhibited the growth of the gram-positive bacteria Staphylococcus epidermidis, but not the gram-negative bacteria Escherichia coli. C. habessinica, P. americana, and E. purpurea alone did not inhibit growth of either bacterial strain.
Conclusions: The results demonstrated that H. canadensis had antibacterial activity against S. epidermidis, but the HMPE formula was not active against S. epidermidis, when a zone of inhibition threshold of 12 millimeters (mm) was used to determine antibiotic activity. Because the HMPE formula was shown to be less effective than H. canadensis alone, the formula might benefit from an increased percentage of H. canadensis.