Biomedica最新文献

Introduction: For over a century, Sporothrix schenckii was considered the sole species responsible for sporotrichosis. In 2007, scientific community confirmed the disease could be caused by various Sporothrix species. These species differed in their virulence factors and their antifungal sensitivity.

Objective: This study aims to characterize 42 Colombian clinical isolates of Sporothrix spp. phenotypically and genotypically.

Material and methods: Forty-two clinical isolates were characterized using phenotypic methods. It involved various culture media to determine their growth range at different temperatures and to assess the type and distribution of pigment and colony texture. Microscopic morphology was evaluated through microcultures, as well as the conidia diameter, type of sporulation, and morphology. Additionally, the assimilation of carbohydrates was selected as a physiological trait for species identification. Genotyping of 40 isolates was performed through partial amplification of the calmodulin gene, followed by sequence analysis.

Results: Molecular studies enabled the identification of 32 isolates of S. schenckii and 8 isolates of S. globosa. The combination of phenotypic and genotypic methods eased these species characterizations and the recognition keys development based on parameters such as growth diameter at 25 and 30 ºC, colony texture (membranous or velvety) on potato dextrose agar, and microscopic morphology with predominance of pigmented triangular, elongated oval globose, or subglobose conidia.

Conclusions: Confirmation of the phenotypic characteristics and molecular analysis is crucial for identifying Sporothrix species and determining adequate treatment. This study represents the first phenotypical and genotypical characterization of clinical isolates of Sporothrix spp. reported in Colombia.

Introduction: The existing methods for Paracoccidioides spp. antigen production are problematic in terms of standardization, specificity, stability, repeatability, and reproducibility.

Objective: To optimize the methodology for Paracoccidioides spp. antigen production and evaluate its applicability in paracoccidioidomycosis immunodiagnosis.

Materials and methods: The antigens were obtained from Paracoccidioides lutzii isolates (01, 66, and 8334), Paracoccidioides brasiliensis sensu stricto (113), and Paracoccidioides restripiensis (B-339). These fungi were grown at 36 °C ± 1 °C, on modified Fava-Netto agar, according to Freitas et al. (2018). Paracoccidioides lutzii antigens were obtained after , 10, and 20 days of culture, whereas P. brasiliensis and P. restripiensis antigens were obtained after 10 days. Antigens were evaluated in natura, 10 and 20 times concentrated. Antigenic capacity was evaluated using a double immunodiffusion assay against serum samples from patients with paracoccidioidomycosis, histoplasmosis, and aspergillosis, and random blood donors.

Results: Cross-reactivity between Paracoccidioides spp. antigens was observed when P. brasiliensis, P. restrepiensis antigens, and P. lutzii antigens were evaluated with the polyclonal antibodies against P. lutzii and P. brasiliensis, respectively. No cross-reactivity was obtained for polyclonal antibodies against Histoplasma capsulatum, Aspergillus fumigatus, and random blood donors. The proposed protocol allowed stable, repeatable, and reproducible genus-specific antigen production at a low cost and in a short cultivation time.

Conclusion: The proposed protocol allowed us to obtain genus-specific antigens that can be developed and reproduced in all laboratories in Brazil and South America, where paracoccidioidomycosis is a neglected disease, contributing to an early diagnosis, especially in endemic regions, regardless of the species.

Introduction: Patients with type 2 diabetes mellitus are susceptible to acquire Candida spp. infections, sometimes involving more than one species. The resistance of some species to antimycotic agents can cause treatment failure.

Objectives: To determine the frequency and clinical varieties of mixed oral candidiasis in patients with type 2 diabetes mellitus, the involved species, and its sensitivity spectra when exposed to antifungals used as candidiasis treatment.

Material and methods: We developed an analytical cross-sectional study with 72 patients with type 2 diabetes mellitus with hyperglycemia (HbA1C ≥ 7%) and an oral candidiasis diagnosis. The causal species of oral candidiasis were identified through microbiological techniques, and sensitivity tests were carried out using the diffusion method in a plate with strips (E-test ®).

Results: We included 72 patients in the study, 32 (44%) males and 40 (56%) females. Patients were divided into three age groups: young adults (17%), adults (74%), and older adults (9%). The mean age of the patients was 51 years. No significant differences were found between mixed oral candidiasis and groups (sex and age), or between mixed oral candidiasis and gender, glycosylated hemoglobin level (HbA1C), antihyperglycemic treatment, or type 2 diabetes mellitus time of diagnosis. We found a correlation between the adult group and development of mixed or simple oral candidiasis. The results showed eight (13%) cases of mixed oral candidiasis: seven with a coinfection of two species and one with a coinfection of three species. The identified species were Candida albicans, C. glabrata, C. dubliniensis, C. kefyr, C. tropicalis, and C. krusei. Most of these species presented sensitivity against ketoconazole and fluconazole, and higher resistance to itraconazole.

Conclusions: Mixed oral candidiasis occurs in approximately 10% of the patients with type 2 diabetes mellitus and its treatment can be ineffective when the etiological agent is not identified.

Fungi are multifaceted organisms found in almost all ecosystems on Earth, where they establish various types of symbiosis with other living beings. Despite being recognized by humans since ancient times, and the high number of works delving into their biology and ecology, much is still unknown about these organisms.Some criteria classically used for their study are nowadays limited, generating confusion in categorizing them, and even more, when trying to understand their genealogical relationships. To identify species within Fungi, phenotypic characters to date are not sufficient, and to construct a broad phylogeny or a phylogeny of a particular group, there are still gaps affecting the generated trees, making them unstable and easily debated.For health professionals, fungal identification at lower levels such as genus and species, is enough to select the most appropriate therapy for their control, understand the epidemiology of clinical pictures associated, and recognize outbreaks and antimicrobial resistance. However, the taxonomic location within the kingdom, information with apparently little relevance, can allow phylogenetic relationships to be established between fungal taxa, facilitating the understanding of their biology, distribution in nature, and pathogenic potential evolution.Advances in molecular biology and computer science techniques from the last 30 years have led to crucial changes aiming to establish the criteria to define a fungal species, allowing us to reach a kind of stable phylogenetic construction. However, there is still a long way to go, and it requires the joint work of the scientific community at a global level and support for basic research.

Introduction: Fungal genera Alternaria and Fusarium include human and plant pathogenic species. Several antifungals have been used for their control, but excessive use has contributed to resistance development in pathogens. An alternative to searching for and developing new antifungal agents is using essential oils and their main components, which have biological activities of interest in medicine and food production.

Objective: To evaluate in vitro and in silico the antifungal activities of terpenoids against Alternaria alternata and Fusarium oxysporum.

Materials and methods: The minimum inhibitory concentration and minimum fungicidal concentration values of 27 constituents of essential oils used against Alternaria alternata and Fusarium oxysporum were evaluated in vitro. In addition, using genetic algorithms, quantitative models of the structure-activity relationship were used to identify the structural and physicochemical properties related to antifungal activity.

Results: The evaluated compounds proved to be effective antifungals. Thymol was the most active with a minimum inhibitory concentration of 91.6 ± 28.8 μg/ml for A. alternata and F. oxysporum. Quantitative structure-activity relationship models revealed the octanolwater cleavage ratio as the molecular property, and the phenols as the main functional group contributing to antifungal activity.

Conclusion: Terpenoids exhibit relevant antifungal activities that should be incorporated into the study of medicinal chemistry. Inclusion of in silico assays in the in vitro evaluation is a valuable tool in the search for and rational design of terpene derivatives as new potential antifungal agents.

Paracoccidioidomycosis is a systemic mycosis endemic in Latin America. The most frequent form involves a chronic compromise of the lungs, skin, and mucosa. The patient started with a single oral lesion that lasted for several years. The absence of other symptoms pointed out a possible malignant neoplasm, specifically a squamous cell carcinoma.Differentiation between both diagnoses –fungal infection and carcinoma– depends on the results of the direct examination, the histopathological study, and the initial and subsequent cultures. However, in this case, those findings were not conclusive. The coexistence of both diagnoses is frequent and increases the diagnostic challenge. After several consultations and tests, direct examination, immunodiffusion and real-time PCR findings the multifocal chronic paracoccidioidomycosis diagnosis was confirmed.This case warns about a systematical absence of clinical suspicion of endemic mycoses before the appereance of mucocutaneous lesions, which can be produced by fungi like Paracoccidioides spp, and the importance of considering those mycoses among the differential diagnoses.

Fungemia caused by Geotrichum spp. is rare and highly lethal. The Instituto Nacional de Cancerología in Bogotá reported just two cases: one in the period 2001-2007 and the other in 2012-2018. This type of infection is more common in any kind of immunocompromised patients, so it can occur in those with hematological malignancies.Here we present the case of a 27-year-old man, diagnosed with acute lymphoblastic leukemia in relapse and admitted with polyarthralgia for five days, febrile neutropenia, nonabscessed cellulitis, and bacteremia due to methicillin-sensitive Staphylococcus aureus. The patient received therapy with oxacillin and cefepime, but the febrile neutropenia persisted.A new set of blood cultures was taken, and antifungal treatment was started because of the suspicion of invasive fungal infection. Arthroconidia were identified in blood cultures and Geotrichum spp. was confirmed using matrix-assisted laser desorption-ionization mass spectrometry. The antifungal treatment was adjusted with amphotericin B deoxycholate for 14 days and voriconazole for four weeks, and after a prolonged stay, the patient was discharged.Although the incidence of fungemia caused by Geotrichum spp. is low, it must be considered in patients with hematological malignancies and persistent febrile neutropenia despite the broadspectrum antimicrobial treatment. The confirmation of fungemia causing agents, with proteomic tools such as the mentioned mass spectrometry, allows treatment adjustment and decreases complications, hospital stay, and mortality.