Pohl-Albertyn, C. H.Hiscock, J. R.Steyn, Hendrik Jacobus Frederik2023-08-162023-08-162023http://hdl.handle.net/11660/12125Dissertation (M.Sc.(Microbiology))--University of the Free State, 2023The ability of naturally occurring substances to inhibit bacterial growth has proven to be one of mankind's cornerstone discoveries (Fleming 1929; Whitehead 1933). The potential of these substances was highlighted when Alexander Fleming noticed the inhibition and lysis of Staphylococcus colonies when cultured in the presence of ascomycetous fungus of the genus Penicillium (Fleming 1929). The ability of Penicillium to inhibit bacterial growth was attributed to the production of a substance termed penicillin (Fleming 1929). A characteristic property of antibacterial substances is their selective action; some substances are effective against either Gram-negative or Gram-positive bacteria and in some instances, both (Waksman 1944). When considering that these substances differ in chemical composition, it is evident that the selective action of antibacterial substances directly relates to their mechanism of action. Additionally, the qualitative characteristic of varying concentrations directly influences the substance's efficacy. It is established that higher concentrations of antibacterial substances result in exaggerated inhibition (Waksman 1944). From these findings, the use and application of antibiotic substances have enabled the treatment of various bacterial infections and revolutionised the healthcare industry (Espinel-Ingroff 2003; Tomson and Vlad 2014). The discovery and application of antibacterial substances promoted the search for antifungal substances (Espinel-Ingroff 1997). The efforts of Elizabeth Hazen and Rachel Brown lead to the discovery of an antifungal substance produced by soil actinomycetes. The substance termed fungicidin or nystatin indicated fungistatic and fungicidal activity (Hazen and Brown 1951). From these findings, other cultures were screened for antifungal substances and inhibitory potential. In 1953, Steinberg and co-workers identified and isolated the antifungal substances amphotericin A and B from a Streptomycete culture (Steinberg et al. 1953, Dutcher 1968). A report by Milton Sloane supported the efficacy of antifungal substances when used in the treatment of candidiasis; proving the use of nystatin to be effective (Sloane 1955).enDissertationUniversity of the Free State