Antifungal activity of four weedy plant extracts against selected mycotoxigenic fungi.

AIMS: To investigate the antifungal activity of aqueous and organic extracts of four weedy plant species viz. Tagetes minuta, Lippia javanica, Amaranthus spinosus and Vigna unguiculata against isolates of four agriculturally important fungi, i.e. Fusarium verticillioides, F. proliferatum, Aspergillus flavus and A. parasiticus. METHODS AND RESULTS: Dried powdered aerial parts of the plants were extracted sequentially with hexane, dichloromethane, methanol and water and tested for activity using a serial microdilution assay. Results were read every day over 120 h. All extracts except for the water extracts showed growth inhibitory activity against most isolates of the Fusarium spp. The most active were the methanol and hexane extracts of V. unguiculata and A. spinosus with minimum inhibitory concentration (MIC) values of <0.5 mg ml(-1) after 48 h against Fusarium spp. No inhibition of the Aspergillus spp. tested was observed, but conidium formation was stimulated on plates treated with plant extracts when visually compared to the growth controls. CONCLUSIONS: The results obtained from this study indicated that chemical constituents from these plant species may be developed as potential agrochemical fungicides. SIGNIFICANCE AND IMPACT OF THE RESEARCH: Food and feed are subject to infection by a variety of micro-organisms that can induce spoilage and/or produce metabolites that are toxic to humans and animals. Extracts of V. unguiculata and A. spinosus were most active and maybe developed into environmentally friendly fungicides, which are affordable to rural farmers in developing countries.

Food preservative potential of essential oils and fractions from Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris against mycotoxigenic fungi.

The food preservative potential of essential oils from three aromatic plants Cymbopogon citratus, Ocimum gratissimum and Thymus vulgaris and their fractions was investigated against two mycotoxigenic strains each of Aspergillus ochraceus, Penicillium expansum and P. verrucosum. The fungicidal activity was determined and expressed as a Number of Decimal Reduction of the colony forming units per ml (NDR cfu). The influence of pH variation on this activity was studied. The NDR cfu varied with the essential oils and its concentration, the pH of the medium and the strain tested. The essential oils from O. gratissimum exhibited the highest activity against the six fungal strains under the three pH tested. T. vulgaris and C. citratus essential oils were less active against the Penicillium species tested and A. ochraceus, respectively. Potassium sorbate did not present any activity at pH 6 and 9. At pH 3, its NDR cfu was the lowest against the six fungal strains. At the same pH and at 4000 ppm, the three essential oils presented a NRD cfu > or = 6 against strains of A. ochraceus and P. expansum. The same result was obtained with T. vulgaris and C. citratus at 8000 ppm against both strains of P. verrucosum. The highest activity of the three essential oils was recorded at pH 3 against A. ochraceus strains and at pH 9 against both species of Penicillium. From the fractionation, three active fractions were obtained each from C. citratus and O. gratissimum, and two active fractions from T. vulgaris. These active fractions exhibited a NDR cfu, two to seven folds higher than that of the complete essential oils.

Corneal ulcer due to Neocosmospora vasinfecta in an immunocompetent patient.

We report a case of Neocosmospora vasinfecta keratitis in a 55-year-old man. While the patient did not recall any specific trauma or eye injury, he might have sustained a trivial wound during the course of his duties as a farmer. Direct examination of corneal scrapings revealed fungus filaments. As topical treatment with natamycin and econazole and subsequent systemic ketoconazole therapy failed, a full thickness therapeutic keratoplasty was performed. Post-operative treatment with amphotericin B and clotrimazole combined with cyclosporine resulted in a complete cure. The residual corneal infiltration in the recipient cornea became clear in a week. The fungal isolate was initially identified as a Fusarium species, but later reidentified through the use of morphological characteristics and sequence analysis of the internal transcribed spacer region as N. vasinfecta. The latters is a Hypocrealean fungus not hitherto reported as a causative agent of keratomycosis.

A preliminary survey of mycological and fumonisin and aflatoxin contamination of African traditional herbal medicines sold in South Africa.

Traditional medicine is an important aspect of healthcare delivery in South Africa and is used by at least 70% of the country's population. The trade in medicinal plants is a multi-million rand business which is a major driver for rural economies. However, the conditions in which these plant products are transported and stored make them prone to fungal contamination which results in economic losses to the traders and pose potential health hazards to consumers. Of major concern is the possible presence of toxigenic fungi and mycotoxins. This study assessed fungal and mycotoxin contamination of African herbal products sold in Cape Town and Tshwane (formerly Pretoria) in South Africa. Of the 16 samples analyzed, 15 were contaminated with at least one of these three fungal genera: Aspergillus, Fusarium, and Penicillium. Fumonisin B(1) was present in 13 of the samples in quantities ranging from 14 to 139 microg/kg (detection limit 5 microg/kg). None of the samples was contaminated with aflatoxigenic fungi or aflatoxin (detection limit 0.5 microg/kg). This is the first study to report on mycological and mycotoxin contamination of commercial traditional African medicines in South Africa. There is a need to expand the study to other urban centers to gain enough insight into this problem and then to intervene with measures that can protect the public from potential harm.

Rhino-orbitocerebral entomophthoramycosis.

Conidiobolus coronatus is recognized as a human pathogen causing subcutaneous fungal infection of the face in immunocompetent patients. The disease process is usually benign. We report, what we believe to be the first case of intracranial extension of C. coronatus producing rhino-orbitocerebral syndrome, and subsequent dissemination of C. coronatus in an immunocompetent patient.

Fusarium dimerum as a cause of human eye infections.

Fusarium dimerum, typically a soil fungus, was isolated from an adult male suffering from a corneal ulcer following an injury to the eye. This fungus has not been described to cause human infections in South Africa and has not been recorded from soil, plant or organic material in this country. The macro- and microscopic characteristics of the isolate were found to be indistinguishable from described strains. Its authenticity was confirmed by comparing it to other human isolates from the eye obtained in the USA, thus rendering this the first report of F. dimerum from an eye infection in a human in South Africa.

The influence of deck storage and initial processing on patulin levels in apple juice.

Patulin, a secondary metabolite produced by Penicillium expansum and some other fungal species, is a common contaminant of ripened apples used for the production of apple juice concentrates. The limited availability of suitable storage facilities may result in fruit being subjected to storage in the open ('deck storage') for extended periods of time, prior to processing. A study was conducted to determine the influence that deck storage and subsequent initial processing practices had on patulin levels in freshly pressed juice. Over the study period, triplicate samples were collected at four strategic processing points from individual consignments of Granny Smith apples deck-stored for 7, 15 and 33 days, respectively. Over the study period, mean patulin levels in non-processed fruit increased from 90 to 2445 ng/g, respectively, but decreased to between 75 and 695 ng/g, respectively, following a water wash step. Subsequent removal of rotten/damaged fruit decreased patulin levels further (to between 55 and 405 ng/g, respectively), although the numerical decreases between sampling points were not shown to be statistically significant (P > 0.05). However, patulin levels were significantly higher (P < 0.05) in the rejected rotten/damaged fruit (mean levels ranged from 1120 to 6235 ng/g, respectively). P. expansum was the major patulin-producing fungus isolated from the juice samples. The mycological analyses tended to support the chemical data, in that removal of the rotten/damaged fractions significantly reduced total fungal counts in the juice samples.

Tinea corporis/cruris: new treatment options.

We undertook a prospective, multicentre, double-blind, placebo controlled, randomised, parallel-group study to evaluate the efficacy and safety of the topical 1% emulsion gel formulation of Lamisil in the treatment of tinea corporis/cruris. Eighty-three patients with clinically and mycologically confirmed tinea corporis/cruris were enrolled from 6 dermatology practices. Of the 62 patients in the intent-to-treat population, 29 were randomised to 1% Lamisil emulsion gel (23 male, 6 female; mean age 42 years, range 19-79 years) and 33 to placebo (25 male, 8 female; mean age 36 years, range 16-73 years). The gels were applied once daily for 1 week. Mycological cure (negative microscopy and culture results) and effectiveness of treatment (mycological cure plus no or minimal signs and symptoms) were measured on day 7, weeks 2, 4 and 8, and at the end of the study. At the study end, rates mycological cure were 83% for Lamisil 1% emulsion gel and 27% for placebo gel (p < 0.001), with respective rates for effective treatment of 83 and 21% (p < 0.001). Complete cure was recorded for 59% of patients receiving Lamisil 1% emulsion gel and 13% of patient receiving placebo gel (p < 0.001). We conclude that a 1-week course of Lamisil 1% emulsion gel is significantly more effective in the treatment of tinea corporis/cruris than placebo gel in respect of complete cure, mycological cure and effective treatment.

Prevalence, epidemiology and geographical distribution of Sporothrix schenckii infections in Gauteng, South Africa.

Sporotrichosis is a subcutaneous fungal infection caused by the traumatic implantation of the dimorphic, pathogenic fungus, Sporothrix schenkii. It constitutes the most common subcutaneous fungal infection in the general population in South Africa. Sporotrichosis in South Africa dates back to 1914, when the disease was first diagnosed in the gold mines. Occupational and recreational circumstances of infection are well established, and the environmental requirements for contracting the disease are better understood. Sporotrichosis cases were recorded from 42 suburbs in the greater Pretoria area as well as from 23 towns outside the Pretoria municipal boundary. It occurred in 154 patients with ages ranging from less than 1 year to 90 years old, with males predominating. Females in the area seemed to be at lesser risk, mainly becoming infected through gardening injuries, insect bites or other minor injuries due to outdoor activities. Exposure to possible sources of the fungus, either from recreational or occupational activities in males, was the main determining factor in acquiring the disease. The lymphocutaneous and localized forms of the disease were most often recorded. Our study indicates that, while there is no pronounced seasonal variation, the onset of the disease seemed to be mainly in the cooler and dryer months of the year.

Microsporum canis scalp ringworm: its primary or secondary ectothrix character.

This study supports the view that, in cases of tinea capitis due to a Microsporum canis infection, ectothrix arthroconidium formation is extrapilary and arises from intrapilary hyphae. The hyphae of M. canis perforate and digest the hair cuticle to alter its appearance from a normally identifiable structure of imbricated cells with a distal free border, to a grossly altered and pathological layer. Conidium production mainly takes place outside the hair shaft and forms thick clusters between the cuticular tiles. Finally, a shaft of conidia is formed around the hair. The cuticular covering of such a conidium sheath belongs to the root sheath of the hair follicle, and not to the hair structure proper.

Mycotic keratitis caused by Curvularia brachyspora (Boedjin). A report of the first case.

Curvularia brachyspora has been identified for the first time as a cause of mycotic keratitis. Mycotic infections of the eye have assumed increasing importance in ophthalmology, resulting in a need for fungal identification and early specific treatment for the successful management of cases. A case of mycotic keratitis caused by C. brachyspora is described against the background of other Curvularia species causing mycoses.

Treatment of cutaneous sporotrichosis with terbinafine.

Terbinafine, an allylamine antifungal agent, has been shown to have excellent in-vitro activity against dermatophytes. Several other fungi of importance also show in-vitro sensitivity. Because terbinafine is fungicidal rather than fungistatic in action, its efficacy in treating such fungal infections requires evaluation. Five patients with cutaneous sporotrichosis were treated with 250 mg of terbinafine twice daily. All of the patients were cured. Overall, the clinical response was rapid. In three patients, negative culture was achieved within 8 weeks; in the other two, negative culture was obtained at 12 and 32 weeks, respectively. Terbinafine was well tolerated, although one patient developed erectile dysfunction while receiving treatment. This was completely resolved on stopping the treatment. The treatment of sporotrichosis is also reviewed in this article.

Botryomycosis. Some African cases.

Botryomycosis is a rare and chronic but readily treatable form of mycetoma. It is caused by a persistent bacterial infection and is distinguished by the formation of grains and multiple sinuses in the skin. The most usual cause is caused by Staphylococcus aureus. The authors' experience with four Transvaal cases is reported. In one case there was destruction of the skull and penetration of the cranial cavity by the botryomycotic process. Treatment with a range of common antistaphylococcal antibiotics led to astonishingly rapid recovery. Among the drugs used, cotrimoxazole was, perhaps, the most practical.

Superficial fungal infections in the Transvaal. A contemporary analysis of dermatophytoses in this region.

An 8-year survey of patients from hospital clinics and private practices in Pretoria seeking specialist dermatological advice for dermatophytoses revealed almost 500 cases, which were confirmed by mycological study. Correlation of the data with other localities was made to illustrate the epidemiology for several common dermatophytes in the Transvaal. Trichophyton rubrum (27%) proved to be the most prominent dermatophyte, followed by T. mentagrophytes (23%), Microsporum canis (19%), T. violaceum (18%) and Epidermophyton floccosum (12%), while M. gypseum occurred in only 1% of the cases. Mapped lists of the published dermatophyte species isolated in southern Africa over the past three decades are presented.

The septal ontogeny, germination and electron microscopy of Microsporum gypseum macroaleurioconidia.

Microsporum gypseum strains obtained from human and animal cases of dermatophytosis were used to study the septal ontogeny, the germination, and the electron microscopy of the macroaleurioconidia, which are produced so abundantly by this organism. It was found that the number of septa in a macroaleurioconidium depends upon the stage of development, and that their order of formation remains relatively constant. The macroaleurioconidial cell wall proved to be impressive on electron microscopy. The use of a wetting agent (Tween 80) and negative pressure proved necessary for adequate fixation. Poor penetration of the fixing agent is attributable to the electron-dense encrustations over the entire surface of the macroaleurioconidium.

Studies in sporotrichosis: fungal morphogenesis and pathogenicity in differing environments.

Sporothrix schenckii exhibits different morphology and pathogenic properties according to the source and circumstances of its growth. The present study considers the morphology and experimental pathogenicity in relation to - the 'wild' strains; the possible circumstances enhancing pathogenicity in strains recovered from the soil; the rate and nature of the transformational steps in morphology, in human and experimental infections by established pathogenic strains; the elimination of pathogenic strains to the surface of clinical lesions, enabling a simplified diagnostic proof of infection; the rate and nature of the reversion of pathogenic forms to the 'wild' type when the constraints of the host are lessened; the plasticity of conidium-pigmentation as a sign of pathogenicity; the morphological conversions on moist wattle-wood as occur in the Gold Mines; and a note on the therapeutic value of itraconazole. Host resistance is seen to play a larger part in morphology of the pathogenic phase, and exhaustion of natural food resources as the generator of potentially pathogenic forms.

Studies on sporotrichosis. Pathogenicity and morphogenesis in the Transvaal strains of Sporothrix schenckii.

In the Transvaal, two epidemiologic patterns of Sporothrix infection occur in man. Evidence gathered from nature, the clinic and the laboratory suggests that these patterns are not the result of either a fixed strain specificity or a random mutation. The differences represent a developmental trend, determined by environmental factors, which gradually transform the wild strains of Sporothrix schenckii into variants resembling the earlier descriptions of Sporothrix beurmannii. This change, moreover, is regular and predictable.

Subcutaneous phycomycosis caused by Basidiobolus haptaosporus (Drechsler, 1947).

Subcutaneous phycomycosis in a Black child is reported, together with clinical, histological and mycological studies. This is the first case, to our knowledge, to be identified mycologically in South Africa. Oral potassium iodide gave an excellent therapeutic result.

Spore ultrastructure in Sporothrix schenckii.

Pathogenic strains of Sporothrix schenkii may show triangular spores, whose angular shape is maintained by a tie-beam effect in the inner cell wall structure. This difference in wall structure lies adjacent to a folded and possibly more active part of the spore cytoplasm. The supposed generation of asci in old cultures was simulated by the death of hyphae which are reinvaded by intrahyphal growth with intrahyphal spore production, while true asci were not seen.