The antimicrobial activity of five food spices when tested against various gram-positive –and gram-negative microorganisms
Loading...
Date
2008
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The discovery of antibiotics by Alexander Fleming in the early nineteen hundreds not only created an enormous breakthrough in medical treatment but along with it introduced the emergence of new and now what is considered an ever increasing number of multi-drug resistant pathogens. Like antibiotics, herbs and spices have been used traditionally by many, for the treatment of various aliments ranging from stomach indigestion, lesions of the skin to beauty therapy. At present it is estimated that about 80% of the world population rely on botanical preparations as medicines to meet their health needs as opposed to treatment by conventional medicine with spices creating a shelf of its own in the global medical cabinet.
In this study, the antimicrobial potential of five spices (commonly known as ginger, cinnamon, turmeric, nutmeg and chilli) was analysed against various Gram positive- and Gram negative microorganisms namely, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Salmonella spp, Shigella spp and Staphylococcus aureus. Analysis of the results of sensitivity tests (disc and agar well diffusion assays) indicated each of the microorganisms to be completely inhibited, intermediately inhibited or completely resistant towards a particular spice extract. The formation of zones of inhibition present where inhibition had occurred indicated that the spice tested was effective as an antimicrobial agent when screened. Zones of absolute inhibition (greater than fifteen millimetres in diameter) were obtained during positive agar well and disc diffusion assaying with neomycin used as the antimicrobial agent of choice. Inhibition zones observed to be in the upper limit range (pertaining to the study) of 20 mm – 27 mm in diameter. Comparative studies using the test spices indicated that chilli, turmeric, nutmeg, cinnamon and ginger each demonstrated zones of inhibition within this limit at one or more laboratory testing. Chilli was the most active antimicrobial agent when tested and in some instances demonstrated antimicrobial effectiveness greater than that exhibited by the positive control neomycin. Turmeric, nutmeg, cinnamon and ginger however each demonstrated inhibition within the same range as that of neomycin. The observations of such inhibition amongst the spices were comparatively significant and demonstrated the potential use of these spices as antimicrobial agents with an efficacy that can be compared to that of the already recognized and widely used antibiotic, neomycin.
The minimum inhibitory concentration (MIC) was successfully determined for each of the spice extracts. The reactions observed during MIC determination were confirmatory of the antimicrobial activity present in the extracts of each spice. Analyses of the results conclude that the active compounds present in the selected spices were effective against certain microbial species. This observation demonstrated that spice can and may be used in the treatment of bacterial infections. This could in the future be an alternative treatment to antibiotics for one or all of the microbial species investigated and in so doing allow the healing powers of spices to be acknowledged.
Description
A dissertation by Kashimee Seepersad
Submitted in fulfilment of the requirements for the degree of
Master of Science
In the Department of Biochemistry and
Microbiology, Faculty of Science and Agriculture,
University of Zululand, 2008.
Keywords
Antimicrobial activity, Food spices