Browsing by Author "Botha, Alfred"
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- Item50 years of Emmonsia disease in humans : the dramatic emergence of a cluster of novel fungal pathogens(Public Library of Science, 2015) Schwartz, Ilan S.; Kenyon, Chris; Feng, Peiying; Govender, Nelesh P.; Dukik, Karolina; Sigler, Lynne; Jiang, Yanping; Stielow, J. Benjamin; Munoz, Jose F.; Cuomo, Christina A.; Botha, Alfred; Stchigel, Alberto M.; De Hoog, G. SybrenNew species of Emmonsia-like fungi, with phylogenetic and clinical similarities to Blastomyces and Histoplasma, have emerged as causes of systemic human mycoses worldwide. They differ from classical Emmonsia species by producing a thermally-dependent, yeast-like phase rather than adiaspores, and by causing disseminated infections, predominantly in immunocompromised patients and often with high case-fatality rates. Such differences will be important for clinicians to consider in diagnosis and patient management, and for microbiologists who may encounter these fungi with increasing frequency.
- ItemDesigned antimicrobial peptides for recurrent vulvovaginal candidiasis treatment(American Society for Microbiology, 2019) Woodburn, Kathryn W.; Clemens, L. Edward; Jaynes, Jesse; Joubert, Lydia-Marie; Botha, Alfred; Nazik, Hasan; Stevense, David A.Recurrent vulvovaginal candidiasis (RVVC) is a widespread chronic infection that has a substantial negative impact on work and quality of life. The development of antimicrobial resistance and biofilm formation are speculated to contribute to Candida pathogenicity and treatment ineffectiveness. Designed antimicrobial peptides (dAMPs) are chemically modified from endogenous antimicrobial peptides that provide the first line of defense against pathogens. The goal here is to identify a dAMP for the topical treatment of RVVC. The dAMP MICs were determined for 46 fluconazole-susceptible and fluconazole-resistant Candida spp. clinical isolates. The possibility of inducing dAMP drug resistance and comparison of dAMP and fluconazole activity against preformed Candida biofilm and biofilm formation were evaluated. Assessment of mammalian cell viability was determined using bioluminescent human keratinocytes. The dAMP effect on fungus was probed via scanning electron microscopy, and topically applied dAMP activity was evaluated in a rodent vulvovaginal candidiasis (VVC) infection model. dAMPs demonstrated broad-spectrum antimicrobial activity against common causative clinical Candida isolates, reduced preformed biofilm, and inhibited biofilm formation. An evaluated dAMP did not induce resistance after repeated exposure of Candida tropicalis. The dAMPs were selective for Candida cells with limited mammalian cytotoxicity with substantial activity in a rodent VVC model. dAMPs are described as having potent antifungal and antibiofilm activity, likely direct membrane action with selectivity for Candida cells, with limited resistance development. Combined with activity in a rodent VVC model, the data support clinical evaluation of dAMPs for topical treatment of VCC and recurrent VVC infections.
- ItemDraft genome sequence of the lignocellulose-degrading ascomycete coniochaeta pulveracea CAB(American Society for Microbiology, 2019-01-03) Borstlap, Cornelius Johannes; de Witt, Riaan Neethling; Botha, Alfred; Volschenk, HeinrichConiochaeta pulveracea is a soft-rot-causing ascomycete able to degrade lignocellulosic biomass. The first draft genome sequence of strain CAB 683 reported here has an estimated size of 30 Mb assembled into 852 scaffolds and 10,035 predicted protein-coding genes.
- ItemEmergomyces : the global rise of new dimorphic fungal pathogens(Public Library of Science, 2019) Schwartz, Ilan S.; Govender, Nelesh P.; Sigler, Lynne; Jiang, Yanping; Maphang, Tsidiso G.; Toplis, Barbra; Botha, Alfred; Dukik, Karolina; Hoving, J. Claire; Munoz, Jose F.; De Hoog, Sybren; Cuomo, Christina A.; Colebunders, Robert; Kenyon, ChrisUnknown until recently, the genus Emergomyces is composed of dimorphic fungi with human pathogenic potential. Five described species have been implicated as causes of disease in immunocompromised persons on at least 4 continents. In some regions, such as southern Africa, this disease, emergomycosis, is now the most commonly diagnosed dimorphic fungal infection. Herein, we review the history of these fungi, clinical features and pathogenesis of disease, what is known of their biology, and future research directions.
- ItemEmergomyces africanus in soil, South Africa(Centers for Disease Control and Prevention, 2018-02) Schwartz, Ilan S.; Lerm, Barbra; Hoving, J. Claire; Kenyon, Chris; Horsnell, William G.; Basson, W. Joan; Otieno-Odhiambo, Patricia; Govender, Nelesh P.; Colebunders, Robert; Botha, AlfredWe detected Emergomyces africanus, a thermally dimorphic fungus that causes an HIV-associated systemic mycosis, by PCR in 18 (30%) of 60 soil samples from a wide range of habitats in South Africa. Direct and indirect culture techniques were unsuccessful. Experimental intraperitoneal inoculation of conidia induced murine disease.
- ItemFungi associated with the skin of a southern right whale (Eubalaena australis) from South Africa(Taylor & Francis group, 2010-09) Reeb, Desray; Best, Peter; Botha, Alfred; Cloete, Karen J.; Thornton, Meredith; Mouton, MarnelCutaneous fungi are known to affect parts of the outermost skin layers of mammals, including the epidermis, stratum spinosum and stratum corneum, as well as mucocutaneous membranes, genitalia or external ears. Relatively little is known about fungal infections of Mysticete cetaceans and studies are needed to determine the fungal diversity associated with these marine mammals. This case report was aimed at identifying the fungi associated with the skin of a diseased neonatal southern right whale (Eubalaena australis) found stranded in the Western Cape Province of South Africa. Initial physical examination on site revealed hyperplasia of the follicular and epidermal epithelium. Preliminary examination of skin biopsies using scanning electron microscopy indicated that the skin was colonized by fungal hyphae. Isolation methods yielded a number of fungal isolates, which were identified using standard morphology and rDNA sequence data. These analyses confirmed colonization of the cutaneous layers by species belonging to the genera Fusarium, Chaetomium and Penicillium. Moreover, all isolates were capable of degrading keratin, indicating that skin may act as a natural substrate for these fungi. This study is the first report of the association of these fungi with southern right whale skin.
- ItemThe intimate relationship between man and yeast : it's complicated(Stellenbosch : University of Stellenbosch, 2011-06) Botha, Alfred; Stellenbosch University Language CentreInaugural address delivered on 6 June 2011 by prof Alf Botha.Yeasts public health service; resource allocation; have been associated with mankind’s welfare for a long time. For millennia these unicellular fungi were cultivated by man as a source of food and drink. However, it was only some 140 years ago that Pasteur demonstrated that live yeast is essential for beer and wine fermentations (Pasteur, 1866; 1876). Since then, these organisms were also found to have biotechnological potential in the production of vitamins (Roman, 1957), fine chemicals (Botes et al., 2005; Miao et al., 2011), enzymes (Steyn & Pretorius, 1990), biofuel (Lynd et al., 2002) and even single-cell proteins (Du Preez, 1990; Roman, 1957). However, yeasts are not only important for industrial biotechnology, but these fungi also have potential uses in agriculture. Some yeasts were found to be beneficial for mycorrhizal interactions during which crop performance is enhanced (Fracchia et al., 2003), others inhibit growth of post harvest pathogens on damaged fruit (Chand-Goyal & Spotts, 1997; Roberts, 1990), while a few species are currently being included in biological fertilisers that are claimed to enhance soil quality. However, yeasts may also be detrimental to mankind since a number of species may act as opportunistic pathogens of humans (Ikeda et al., 2002; Lamagni et al., 2001). This phenomenon is of great importance to an ever-increasing immunocompromised human population suffering from HIV/Aids. The extraordinary progress made in yeast biology may largely be ascribed to decades of studying the intrinsic characteristics of these organisms while growing in pure culture (Kurtzman & Fell, 1998; Lodder, 1971). Thus, during the last two hundred years yeast morphology, metabolism, as well as classical and molecular biology, was always at the frontiers of the biological sciences of the time. This review takes a closer look at the reasons for man’s fascination with this versatile group of organisms and focuses on one of the new frontiers in yeast biology, that of its ecology in natural environments. However, before we can explore this realm of science, we first need to obtain a better understanding of the general characteristics of these microscopic eukaryotes that have captured the imagination of so many biologists over the decades.
- ItemMolecular detection of airborne Emergomyces africanus, a thermally dimorphic fungal pathogen, in Cape Town, South Africa(Public Library of Science, 2018) Schwartz, Ilan S.; McLoud, Josh D.; Berman, Dilys; Botha, Alfred; Lerm, Barbra; Colebunders, Robert; Levetin, Estelle; Kenyon, ChrisEmergomyces africanus is a thermally dimorphic fungus that causes a systemic mycosis in immunocompromised persons in South Africa. Infection is presumed to follow inhalation of airborne propagules. We developed a quantitative PCR protocol able to detect as few as 5 Es. africanus propagules per day. Samples were collected in Cape Town, South Africa over 50 weeks by a Burkard spore trap with an alternate orifice. We detected Es. africanus in air samples from 34 days (10%) distributed over 11 weeks. These results suggest environmental exposure to airborne Es. africanus propagules occurs more commonly in endemic areas than previously appreciated.
- ItemDie uitwerking van die onkruiddoder Roundup op sommige populasies van grondmikrobes(AOSIS Publishing, 2011-09) Marais, Anelia; Ferreira, Michael I.; Booyse, Marde; Botha, AlfredDie glifosaatbevattende onkruiddoder, Roundup®, word wêreldwyd vir onkruidbeheer gebruik. Alhoewel hierdie onkruiddoder beskou word as ‘n lae-toksiese (en dus veilige) produk, heers daar tog kommer oor die langdurige effek daarvan op grondmikrobes, plante, diere en die mens. Verskeie artikels in die meer populêre media en internet verwys na die gevare van Roundup®. Grondmikrobes speel ‘n belangrike rol in die afbraak van landbouchemikalieë. Daar is boere wat sukrose of melasse as ‘n voedselaanvulling vir grondmikrobes gebruik. Sommige boere meng dit ook met onkruiddoders ten einde die moontlike nadelige effek daarvan op voordelige grondmikrobes te verminder, deur hulle van ‘n eenvoudige koolstofbron te voorsien. Die effek van Roundup®, met en sonder die byvoeging van sukrose, is gedurende hierdie ondersoek bepaal met betrekking tot sommige aspekte van die mikrobiologiese gemeenskappe in die grond. Grondmonsters is by drie geleenthede geneem, naamlik voor behandeling, ‘n week daarna en 20 dae daarna. Hierdie grondmonsters is daarrna gebruik vir die meting van kweekbare protosoë (mees-waarskynlike-getal) en metaboliese potensiaal van hoofsaaklik die bakteriese grondgemeenskap (Biolog EcoplateTM), terwyl die filamentagtige groei in situ (versteekte-plaatjie-tegniek) bepaal is. Die byvoeging van suiker het nie ‘n betekenisvolle effek gehad op die werking van die onkruiddoder nie. Terwyl Roundup® wel die metabolisme van die grondbakterieë beduidend verander het, het die bakteriegemeenskap na 20 dae, waarskynlik as gevolg van natuurlike prosesse, herstel.
- ItemYeast infection in a beached southern right whale (Eubalaena australis) neonate(Wildlife Disease Association, 2009) Mouton, Marnel; Reeb, Desray; Botha, Alfred; Best, PeterA female southern right whale (Eubalaena australis) neonate was found stranded on the Western Cape coast of southern Africa. Skin samples were taken the same day from three different locations on the animal’s body and stored at 220 C. Isolation through repetitive culture of these skin sections yielded a single yeast species, Candida zeylanoides. Total genomic DNA also was isolated directly from skin samples. Polymerase chain reaction analysis of the internal transcribed spacer region of the fungal ribosomal gene cluster revealed the presence of Filobasidiella neoformans var. neoformans, the teleomorphic state of Cryptococcus neoformans. Fungal infections in cetaceans seem to be limited when compared to infections caused by bacteria, viruses and parasites. However, Candida species appear to be the most common type of fungal infection associated with cetaceans. To our knowledge this is the first report of a C. zeylanoides infection in a mysticete, as well as the first report of a dual infection involving two opportunistic pathogenic yeast species in a cetacean.