Abstract
Antibiotic resistance has become one of the largest threats to the health of human beings worldwide. The combination of large amounts of antibiotics prescribed over many decades has resulted in the rapid development of bacterial resistance. The spread of multiple antibiotic resistant organisms are becoming more prevalent, traditional antibiotics are no longer effective and the rate at which new antibiotics are developed has significantly dropped in the last decades. There is an urgent need for new therapeutic approaches for the treatment of illnesses caused by bacteria. The aim of this study was to determine the antimicrobial effect of Hydrastis canadensis herbal extract and Hydrastis canadensis mother tincture on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) reference strains. These organisms where chosen since infections caused by them are commonly treated with a wide variety of antibiotics that produces undesirable side effects. S. aureus and E. coli have developed resistance to many classes of antibiotics which makes formerly treatable conditions increasingly difficult to treat. This study was done by means of the Kirby-Bauer Disk Diffusion Method and Microdilution method to determine the Minimum Inhibitory Concentration (MIC) of the Hydrastis canadensis herbal extract and Hydrastis canadensis mother tincture. Cultures on agar plates (for use with the Kirby-Bauer Disk Diffusion test) or in liquid cultures (for use with broth dilution cultures) were grown overnight at 35°C for 16-18 hours. Sterile disks were impregnated with the Hydrastis canadensis herbal extract and Hydrastis canadensis mother tincture. Following incubation the plates were examined for a zone of inhibition of bacterial growth and the zone measured in millimetres. To determine the Minimum Inhibitory Concentration (MIC) of the compounds, the serial dilution method in 96 well plates were tested, labeled and into each well 100 µl Mueller-Hinton broth was added. The compound to be tested (50 µl) was added to the first V well, mixed and 50 µl removed, added to the next well and repeated for the next four wells. The 50 µl removed from the sixth well and discarded. After the incubation period 50 µl Iodonitrotetrazolium chloride (INT) dye was added to the wells, incubated at 35°C for up to 30 min, to produce a pink to dark purple color. The results demonstrated that Hydrastis canadensis herbal extract and Hydrastis canadensis mother tincture inhibited the growth of S. aureus which was confirmed by the Kirby-Bauer Disk Diffusion and Microdilution methods. The Hydrastis canadensis herbal extract and Hydrastis canadensis mother tincture inhibited the growth of E. coli but was only confirmed by the adaptation of the 96 well microdilution methods by increasing the concentration of the Hydrastis canadensis herbal extract and Hydrastis canadensis mother tincture as well as forcing the E. coli into contact with the substances. The Hydrastis canadensis herbal extract and Hydrastis canadensis mother tincture showed no antimicrobial effects when tested with the Kirby-Bauer Disk Diffusion method as bacterial swarming, minimum dosing or decreased concentration of the active compounds could have been a factor. Further investigation into why the Microdilution method yielded positive results rather than the Kirby-Bauer Disk Diffusion method for E. coli found that E. coli’s flagella driven motility allowed the bacteria to swim away and protect itself from the compound resulting in a false negative. When E. coli was forced into contact with the compound, inhibition of growth was observed. Overall it was found that the herbal extract had a greater antimicrobial effect than the mother tincture. In conclusion, Hydrastis canadensis did work against S. aureus and to an extent against E. coli when forced into contact with the Hydrastis canadensis but we need a better understanding of whether it is bactericidal or bacteriostatic. It needs to be ensured that when using this, it is the correct method and that we test and expand the number of strains to determine if there is no interchange and how it relates to antibiotic resistance.
M.Tech. (Homoeopathy)