Revista Iberoamericana De Micologia最新文献

Background: In China, the isolation rate of fluconazole-resistant isolates of Candida tropicalis, together with fatality in cases of bloodstream infections due to this yeast, have increased annually.

Aims: This study investigates the clinical characteristics, risk factors, and prognostic factors of fluconazole-resistant C. tropicalis bloodstream infections (BSI).

Methods: A retrospective study analyzed clinical data of patients with C. tropicalis BSI from July 2013 to June 2019, focusing on clinical characteristics, risk factors, treatment regimens, and prognosis. Univariate analysis of risk factors and prognosis was conducted using x² test or Fisher's exact tests. Binary logistic regression model for risk factors, and Cox regression method for prognosis, were used for multivariate analysis.

Results: The study enrolled 100 patients with C. tropicalis BSI, including 44 fluconazole-resistant and 56 fluconazole-sensitive cases; 64 patients were cured and 36 died, resulting in a mortality rate of 36%. Logistic regression analysis identified exposure to azole antifungal agents during the 2 weeks prior to the onset of the BSI as a risk factor for fluconazole resistance. Cox regression analysis showed that hematological malignancy, fluconazole-resistant strains, indwelling catheters, and chronic obstructive pulmonary disease were independent risk factors for patient mortality. Conversely, targeted therapy with sensitive antifungal agents and removal of drainage tubes were protective factors for survival.

Conclusions:  Azole exposure led to the development of fluconazole resistance in C. tropicalis BSI; hematologic malignancies, azole resistance, chronic obstructive pulmonary disease and having intravenous catheters increased mortality rate. The use of echinocandins or amphotericin B and catheter removal improved outcomes, underscoring the need for early resistance detection and targeted treatment.

Background: During the COVID-19 pandemic, Rhizopus arrhizus and Rhizopus homothallicus were identified as causative agents of rhino-cerebral mucormycosis in COVID-19 patients. Clinical management typically includes surgical debridement and antifungal treatment, with amphotericin B (AMB) and posaconazole (PCZ) as primary options. However, long-term use of AMB can lead to toxicity, necessitating PCZ as a follow-up treatment.

Aims: This study aimed to examine the combined effect of AMB and PCZ on R. homothallicus.

Methods: The combined effect of AmB and PCZ on R. homothallicus was studied by examining their minimum inhibitory concentration (MIC) values, fractional inhibitory concentration index (FICI), spore germination properties, viability, and intracellular reactive oxygen species accumulation; Raman spectroscopy was also performed.

Results: The MIC values for AmB and PCZ were 4 and 8 µg/mL, respectively, with a combined MIC of 2 µg/mL and an FICI index of <0.28. The germination rates at MIC values after 48 h of exposure were 28% for AmB, 36% for PCZ, and only 3% for the combination. Viability assays revealed dead sporangiospores following combination treatment. AmB and its combination generated more ROS (68.18% and 64.45%, respectively) than did PCZ alone (42.6%).

Conclusions: Combination therapy reduced the AMB dose without loss of efficacy, suggesting a synergistic effect against R. homothallicus. These results may support this alternative strategy to mitigate the side effects of AMB.

Background: Infective endocarditis caused by Trichosporon inkin is an exceptionally rare fungal infection, particularly in immunocompetent patients. This microorganism is part of the normal microbiota of the skin and gastrointestinal tract, but can cause invasive infections associated with prosthetic devices or complex clinical conditions. Reported cases in the literature are scarce, making it difficult to establish standardized diagnostic and therapeutic guidelines.

Case report: We report the case of an immunocompetent female patient with rheumatic fever due to which she underwent a mitral valve replacement procedure using a mechanical prosthesis, who developed infective endocarditis caused by T. inkin. The initial diagnosis was delayed due to misinterpretation as contaminant of the fungal isolate recovered. The patient developed intracerebral hemorrhage and was considered high-risk for surgical intervention; thus, medical management was pursued. The microorganism was finally identified by MALDI-TOF mass spectrometry, a validated tool for identifying Trichosporon species. The patient received voriconazole, with favorable clinical response, followed by prolonged suppressive fluconazole therapy.

Conclusions: This is the second case reported in the Americas and the fifth worldwide of T. inkin infective endocarditis in an immunocompetent patient. It highlights the importance of considering this pathogen in prosthetic valve endocarditis in cases of unusual culture results, and demonstrates the diagnostic value of MALDI-TOF. Long-term antifungal therapy with triazoles, particularly voriconazole followed by fluconazole, may be an effective alternative for patients who are not surgical candidates.

Background: In Mexico, Cryptococcus gattii sensu lato has been identified as the etiologic agent in approximately 10.8% of cryptococcosis cases; however, its isolation from natural sources, which would confirm its existence in the environment, has not been successful.

Objective: To isolate C. gattii from environmental samples collected from trees within the movement area of a patient diagnosed with cryptococcosis caused by this species.

Methods: Based on a database of clinical isolates characterized as C. gattii, a patient was contacted and his route of movement was obtained; through a geospatial analysis, nearby trees were located. Tree hollows were sampled and the Cryptococcus isolates obtained were biochemically and genetically typed.

Results: Four Cryptococcus isolates were obtained from the trees Schinus molle, Erythrina coralloides and from a specimen of the genus Pinus: three of them were characterized as Cryptococcus neoformans sensu stricto and one as C. gattii sensu stricto.

Conclusions: Using a geographic information system led to delimit an environmental sampling area, resulting in the first documented report in Mexico of the isolation of C. gattii genotype VGI in nature.