Evaluation of the disk-diffusion method to determine the in vitro efficacy of terbinafine against subcutaneous and superficial mycoses agents

CHARACTERIZATION OF THE FUNGAL MICROBIOTA IN THE NOSTRILS AND RECTUM OF AMAZONIAN MANATEES (TRICHECHUS INUNGUIS) FROM A REHABILITATION PROGRAM IN BRAZIL

The present study characterized the filamentous and yeast-like fungal microbiota of the nasal cavity and rectum of Amazonian manatees (Trichechus inunguis) undergoing rehabilitation at the Laboratory of Aquatic Mammals, National Institute of Amazonian Research, Manaus, Amazonas, and determined the antifungal susceptibility of these organisms. Nasal and rectal swabs were collected from 22 calves and three juveniles. The samples were seeded in Sabouraud agar supplemented with chloramphenicol 10%, incubated at 26°C, and observed daily for up to 7 d. The growth of different filamentous and yeast-like fungi was observed among the two anatomical sites. Filamentous fungi were categorized by macro- and microscopic characteristics of the colonies. Representatives of each group were selected for molecular identification based on the internal transcribed spacer region. Yeast identification was performed using MALDI-TOF MS and molecular analyses. Thirteen genera of filamentous fungi and six genera of yeasts were isolated and identified. The dominant filamentous species were Fusarium spp., Aspergillus spp., and Cochliobolus lunatus in the nostril samples and Aspergillus melleus in the rectal samples. Candida was the dominant genus among the identified yeasts at both anatomical sites. In the antifungal susceptibility test, 28 isolates showed resistance to fluconazole (78%), itraconazole (39%), and nystatin (42%). The knowledge of fungal microbiota composition of Amazonian manatees provides information that assists in monitoring the health status of individuals maintained in captivity, as these organisms can behave either as opportunists or as primary pathogens. Moreover, the composition and resistance of these organisms may vary among different rehabilitation institutions or different time frames of search, reinforcing the importance of constant in loco surveillance of these microorganisms. This study provides new perspectives on the fungal diversity in the microbiota of manatees and supports future studies concerning the clinical and epidemiological aspects and the impacts of these agents on the health of Amazonian manatees undergoing rehabilitation.

Evaluation of susceptibility and response in the surface of agents of surface mycoses (Trichophyton mentagrophytes; T. tonsurans) to antifungal drugs of interest in a medical clinic

Introduction: The resistance of fungal species to drugs usually used in clinics is of great interest in the medical field. Objective: To evaluate susceptibility and in vitro response of species of Trichophyton spp. to antifungal drugs of interest in clinical medicine. Methods: 12 samples of clinical isolates from humans were used, nine of T. mentagrophytes and three of T. tonsurans. Susceptibility tests were performed according to the agar diffusion (AD) and broth microdilution (BM) methods. Results: In the AD method, the species T. tonsurans presented a percentage of sensitivity of 33% in relation to amphotericin B and 66% to itraconazole, with 100% resistance to ketoconazole and fluconazole. T. mentagrophytes also showed 100% resistance to ketoconazole in this technique, with 11% sensitivity to ketoconazole, 22% to itraconazole and 22% of samples classified as sensitive dose dependent. In the MC method, the species T. tonsurans presented a sensitivity percentage of 66%, 55% and 33% in relation to ketoconazole, fluconazole and itraconazole, respectively. The T. mentagrophytes species presented sensitivity percentages of 11%, 11%, 33% and 55% for amphotericin B, itraconazole, ketoconazole and fluconazole, respectively. Conclusion: There was resistance in vitro of the species of T. mentagrophytes and T. tonsurans against the antifungal fluconazole and relative resistance against ketoconazole in the AD method. In BM, however, important percentages of sensitivity were observed for the two species analyzed in relation to the antifungals fluconazole and ketoconazole when compared to itraconazole and amphotericin B.

Fabrication of Ultra-Pure Anisotropic Zinc Oxide Nanoparticles via Simple and Cost-Effective Route: Implications for UTI and EAC Medications

The purposes of this work are to evaluate the antimicrobial, antibiofilm, anticancer, and antioxidant abilities of anisotropic zinc oxide nanoparticles (ZnO NPs) synthesized by a cost-effective and eco-friendly sol-gel method. The synthesized ZnO NPs were entirely characterized by UV-Vis, XRD, FTIR, HRTEM, zeta potential, SEM mapping, BET surface analyzer, and EDX elemental analysis. Antimicrobial and antibiofilm activities of ZnO NPs were investigated against multidrug-resistant (MDR) bacteria and yeast causing serious diseases like urinary tract infection (UTI). The anticancer activity was performed against Ehrlich ascites carcinoma (EAC). Additionally, antioxidant scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) was observed. The synthesized ZnO NPs exhibited an absorption peak at 385.0 nm characteristic to the surface plasmon resonance (SPR). Data obtained from HRTEM, SEM, and XRD confirmed the anisotropic crystalline nature of the prepared ZnO NPs with an average particle size of 68.2 nm. The calculated surface area of the prepared ZnO NPs was 10.62 m²/g and the porosity was 13.16%, while pore volume was calculated to be 0.013 cm³/g and the average pore size was about 3.10 nm. The prepared ZnO NPs showed promising antimicrobial activity against all tested UTI-causing pathogens. It showed a prominent antimicrobial capability against Candida tropicalis with a zone of inhibition (ZOI) reaching 22.4 mm, 13 mm ZOI for Bacillus subtilis, and 12.5 mm ZOI for Pseudomonas aeruginosa. Additionally, the prepared ZnO NPs showed enhanced biofilm repression of about 79.33%, 72.94%, and 33.68% against B. subtilis, C. tropicalis, and P. aeruginosa, respectively. Moreover, the prepared ZnO NPs had a powerful antioxidant property with 33.0% scavenging ability after applied DPPH assay. Surprisingly, upon ZnO NPs treatment, cancer cell viability reduced from 100 to 58.5% after only 24 h due to their unique antitumor activity. Therefore, according to these outstanding properties, this study could give insights for solving serious industrial, pharmaceutical, and medical challenges, particularly in the EAC and UTI medications.

Controlling methylene blue aggregation: a more efficient alternative to treat Candida albicans infections using photodynamic therapy

Methylene Blue (MB) has been widely used in antimicrobial Photodynamic Therapy (aPDT), however, the mechanisms of action (Type I or Type II) are defined by its state of aggregation. In this sense, the identification of the relationships between aggregation, the mechanisms of action and the effectiveness against microorganisms, as well as the establishment of the means and the formulations that may favor the most effective mechanisms, are essential. Thus, the objective of this study was to assess the in vitro aPDT efficacies against Candida albicans, by using MB in vehicles which may influence the aggregation and present an oral formulation (OF) containing MB, to be used in clinical aPDT procedures. The efficacy of MB at 20 mg L-1 was tested in a range of vehicles (water, physiological solution - NaCl 0.9%, phosphate saline buffer - PBS, sodium dodecyl sulfate 0.25% - SDS and urea 1 mol L-1) in a C. albicans planktonic culture, when using 4.68 J cm-2 of 640 ± 12 nm LED for the irradiations, as well as 5 minutes of pre-irradiation time, together with measuring the UFC mL-1. Based upon these analyses, an OF containing MB in the most effective vehicle was tested in the biofilms, as a proposal for clinical applications. When comparing some of the vehicles, sodium dodecyl sulfate was the only one that enhanced an MB aPDT efficacy in a planktonic C. albicans culture. This OF was tested in the biofilms and 50 mg L-1 MB was necessary, in order to achieve some reduction in the cell viabilities after the various treatments. The light dosimetries still need further adaptations, in order for this formulation to be used in clinical applications. The present research has indicated that the development of this formulation for the control of MB aggregations may result in more effective clinical protocols.

M. Chaves M, Raposo NRB. Antifungal activity of Copaifera langsdorffii Desf oleoresin against dermatophytes

Dermatophytoses are mycoses that affect keratinized tissues in both humans and animals. The aim of this study was to investigate the antifungal activity of the oleoresin extracted from Copaifera langsdorffii Desf. against the strains Microsporum canis ATCC 32903, Microsporum gypseum ATCC 14683, Trichophyton mentagrophytes ATCC 11481 and Trichophyton rubrum CCT 5507. The antimicrobial activity was determined by minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values. Ketoconazole and terbinafine were used as reference drugs. The copaiba oleoresin showed moderate fungicidal activity against T. mentagrophytes ATCC 11481 (MIC and MFC = 170 μg mL⁻¹) and weak fungicidal activity against T. rubrum CCT 5507 (MIC = 1,360 μg mL⁻¹ and MFC = 2,720 μg mL⁻¹). There was no activity against M. canis ATCC 32903 and M. gypseum ATCC 14683. SEM analysis revealed physical damage and morphological alterations such as compression and hyphae clustering in the structure of the fungi exposed to the action of the oleoresin. The results stimulate the achievement of in vivo assays to confirm the benefits of the application of oleoresin extracted from copaiba in the treatment of dermatophytosis, both in humans and in animals.

Oral infections caused by yeasts in patients with head and neck cancer undergoing radiotherapy. Identification of the yeasts and evaluation of their antifungal susceptibility

Yeasts occur as part of the normal human microbiota. Nevertheless, some species are opportunistic, affecting immunocompromised patients such as those undergoing oncologic treatment.

OBJECTIVE

To detect the presence of yeasts in patients suffering from head and neck cancer who are receiving radiation therapy and display lesions in the oral cavity, compatible with candidiasis; and to evaluate the antifungal susceptibility of the isolates recovered.

METHODS

Sixty samples from patients were obtained by swabbing the oral mucosa. Identification of isolates were performed by classical taxonomic, morphological and biochemical methods as well as by using commercial identification kits. Susceptibility to antifungal drugs was determined by the agar diffusion method with Neosensitabs(®) disks.

RESULTS

Forty-six samples (77%) yielded positive findings, and species recovered were: Candida albicans (22 isolates), Candida tropicalis (13 isolates), Candida parapsilosis (six strains), Candida krusei (three strains), Candida dubliniensis and Saccharomyces cerevisiae (one each). All strains were susceptible to itraconazole, clotrimazole, voriconazole, nystatin and amphotericin B. On the other hand, 65% of strains were miconazole-susceptible while 35%, showed intermediate susceptibility. With regard to ketoconazole, only three strains (7%) corresponding to C. albicans (one isolate) and C. krusei (two isolates) displayed intermediate susceptibility. Only C. krusei strains were resistant to fluconazole while all the other species were susceptible. Eventually, only six isolates (13%) were susceptible to terbinafine while the remaining strains were resistant in vitro.

CONCLUSION

Early detection of etiological agents causing lesions, as well as the evaluation of their susceptibility to commonly used drugs, are crucial in order to choose the appropriate treatment that will minimize complications while improving the quality of patients' lives.

Antifungal activities of different extracts of marine macroalgae against dermatophytes and Candida species

Algae are bioactive natural resources, and due to the medical importance of superficial mycoses, we focused the action of macroalgae extracts against dermatophytes and Candida species. Seaweed obtained from the Riacho Doce beach, Alagoas (Brazil), were screened for the antifungal activity, through crude extracts using dichloromethane, chloroform, methanol, ethanol, water and chloroform and hexane fractions of green, brown and red algae in assays with standard strains of the dermatophytes Trichophyton rubrum, T. tonsurans, T. mentagrophytes, Microsporum canis, M. gypseum and yeasts Candida albicans, C. krusei, C. guilliermondi and C. parapsilosis. The M44-A and M27-A2/M38A manuals by CLSI were followed, and the minimum inhibitory concentration (MIC) ranged from 0.03 to 16.00 μg ml(-1), and an inhibition halo of 10.00-25.00 mm was observed for dermatophytes, while for yeast, it was from 8.00 to 16.00 μg ml(-1) and 10.00-15.00 mm. M. canis showed MIC of 0.03 μg ml(-1) and the largest inhibition halo in T. rubrum (25.00 mm) through the use of the methanol extract. For C. albicans, dichloromethane, methanol and ethanol extracts formed the largest inhibition halo. The ethanol extract was shown to be the best inhibiting fungi growth, and chloroform and hexane fractions of H. musciformis inhibited the growth of all dermatophytes and C. albicans, yielding the conclusion that apolar extracts obtained from algae presented the best activity against important pathogenic fungi.