María Angeles Martínez-Rivera

Ultrastructural changes on clinical isolates of Trichophyton rubrum, Trichophyton mentagrophytes, and Microsporum gypseum caused by Solanum chrysotrichum saponin SC-2.

Worldwide, dermatophytoses represent a high percentage of all superficial mycoses. The most frequently isolated dermatophyte is Trichophyton rubrum. Solanum chrysotrichum is a vegetal species widely used in Mexican traditional medicine to treat skin infections; its extract has been used to formulate an herbal medicinal product that is used successfully to treat Tinea pedis. Spirostanic saponin SC-2 from S. Chrysotrichum possesses high activity against dermatophytes. The present study reports the ultrastructural changes observed by means of transmission electron microscopy (TEM) in clinical isolates of T. rubrum, T. mentagrophytes, and Microsporum gypseum induced by saponin SC-2. Strains were grown in RPMI 1640 containing SC-2 (1600 microg/mL). Fungi were harvested at 6, 12, 24, and 48 h; controls without SC-2 were included. T. mentagrophytes was the most susceptible to the SC-2 saponin, followed by M. gypseum, while T. rubrum was the most resistant. The main alterations caused by the SC-2 saponin were as follows: i) loss of cytoplasmic membrane continuity; ii) organelle degradation; iii) to a lesser extent, irreversible damage to the fungal wall; and iv) cellular death.

Exploratory Study on the Clinical and Mycological Effectiveness of a Herbal Medicinal Product from Solanum chrysotrichum in Patients with Candida Yeast-Associated Vaginal Infection

Mexican traditional medicine uses Solanum chrysotrichum to treat fungi-associated dermal and mucosal illness; its methanolic extract is active against dermatophytes and yeasts. Different spirostanic saponins (SC-2-SC-6) were identified as the active molecules; SC-2 was the most active in demonstrating a fungicidal effect against Candida albicans and non-albicans strains. The aim of the present study was to compare the clinical (elimination of signs and symptoms) and mycological effectiveness (negative mycological studies) of an S. chrysotrichum herbal medicinal product (Sc-hmp), standardized in 1.89 mg of SC-2, against ketoconazole (400 mg) in the topical treatment of cervical and/or vaginal infection by Candida. Both treatments (vaginal suppositories) were administered daily during 7 continuous nights. The study included 101 women (49 in the experimental group) with a confirmed clinical condition and positive mycological studies (direct examination and/or culture) of Candida infection. Basal conditions did not show differences between the groups; a moderate clinical picture was present in 62% of the cases, direct examination was positive in 69%, and the culture was positive with C. albicans predominating (65%). At the end of the administration period, both treatments demonstrated 100% tolerability, and clinical cure in 57.14% of S. chrysotrichum-treated cases and in 72.5% of ketoconazole-treated cases (p = 0.16), as well as 62.8% and 97.5% of mycological effectiveness, respectively (p = 0.0 001). We conclude that, at the doses used, Sc-hmp exhibits the same clinical effectiveness as ketoconazole, but with lower percentages of mycological eradication. Additional clinical studies with Sc-hmp are necessary, with increasing doses of SC-2, for improving the clinical and mycological effectiveness.

Parasitic polymorphism of Coccidioides spp

BackgroundCoccidioides spp. is the ethiological agent of coccidioidomycosis, an infection that can be fatal. Its diagnosis is complicated, due to that it shares clinical and histopathological characteristics with other pulmonary mycoses. Coccidioides spp. is a dimorphic fungus and, in its saprobic phase, grows as a mycelium, forming a large amount of arthroconidia. In susceptible persons, arthroconidia induce dimorphic changes into spherules/endospores, a typical parasitic form of Coccidioides spp. In addition, the diversity of mycelial parasitic forms has been observed in clinical specimens; they are scarcely known and produce errors in diagnosis.MethodsWe presented a retrospective study of images from specimens of smears with 15% potassium hydroxide, cytology, and tissue biopsies of a histopathologic collection from patients with coccidioidomycosis seen at a tertiary-care hospital in Mexico City.ResultsThe parasitic polymorphism of Coccidioides spp. observed in the clinical specimens was as follows: i) spherules/endospores in different maturation stages; ii) pleomorphic cells (septate hyphae, hyphae composed of ovoid and spherical cells, and arthroconidia), and iii) fungal ball formation (mycelia with septate hyphae and arthroconidia).ConclusionsThe parasitic polymorphism of Coccidioides spp. includes the following: spherules/endospores, arthroconidia, and different forms of mycelia. This knowledge is important for the accurate diagnosis of coccidioidomycosis. In earlier studies, we proposed the integration of this diversity of forms in the Coccidioides spp. parasitic cycle. The microhabitat surrounding the fungus into the host would favor the parasitic polymorphism of this fungus, and this environment may assist in the evolution toward parasitism of Coccidioides spp.

Antagonistic Interaction of Staphylococcus aureus Toward Candida glabrata During in vitro Biofilm Formation Is Caused by an Apoptotic Mechanism

Background: Infections caused by Candida species and Staphylococcus aureus are associated with biofilm formation. C. albicans–S. aureus interactions are synergistic due to the significant increase in mixed biofilms and improved resistance to vancomycin of S. aureus. C. glabrata and S. aureus both are nosocomial pathogens that cause opportunistic infections in similar host niches. However, there is scarce information concerning the interaction between these last microorganisms. Results: The relationship between C. glabrata and S. aureus was evaluated by estimating the viability of both microorganisms in co-culture of planktonic cells and in single and mixed biofilms. An antagonistic behavior of S. aureus and their cell-free bacterial supernatant (CFBS) toward C. glabrata, both in planktonic form and in biofilms, was demonstrated. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal laser scanning microscopy (CLSM) images showed yeast cells surrounded by bacteria, alterations in intracytoplasmic membranes, and non-viable blastoconidia with intact cell walls. Concomitantly, S. aureus cells remained viable and unaltered. The antagonistic activity of S. aureus toward C. glabrata was not due to cell-to-cell contact but the presence of CFBS, which causes a significant decrement in yeast viability and the formation of numerous lipid droplets (LDs), reactive oxygen species (ROS) accumulation, as well as nuclear alterations, and DNA fragmentation indicating the induction of an apoptotic mechanism. Conclusion: Our results demonstrate that the S. aureus CFBS causes cell death in C. glabrata by an apoptotic mechanism.