Browsing by Author "Tapia, Cecilia"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item A prospective, multi-center study of Candida bloodstream infections in Chile(2019) Santolaya, Maria E.; Thompson, Luis; Tapia, Cecilia; Legarraga, Paulette; Cortés, Claudia; Rabello, Marcela; Valenzuela, Romina; Rojas, Pamela; Rabagliati, RicardoBackground Active surveillance is necessary for improving the management and outcome of patients with candidemia. The aim of this study was to describe epidemiologic and clinical features of candidemia in children and adults in tertiary level hospitals in Chile. Methods We conducted a prospective, multicenter, laboratory-based survey study of candidemia in 26 tertiary care hospitals in Chile, from January 2013 to October 2017. Results A total of 780 episodes of candidemia were included, with a median incidence of 0.47/1,000 admissions. Demographic, clinical and microbiological information of 384 cases of candidemia, from 18 hospitals (7,416 beds), was included in this report. One hundred and thirty-four episodes (35%) occurred in pediatric patients and 250 (65%) in adult population. Candida albicans (39%), Candida parapsilosis (30%) and Candida glabrata (10%) were the leading species, with a significant difference in the distribution of species between ages. The use of central venous catheter and antibiotics were the most frequent risk factors in all age groups (> 70%). Three hundred and fifteen strains were studied for antifungal susceptibility; 21 strains (6.6%) were resistant to fluconazole, itraconazole, voriconazole, anidulafungin or micafungin. The most commonly used antifungal therapies were fluconazole (39%) and echinocandins (36%). The overall 30-day survival was 74.2%, significantly higher in infants (82%) and children (86%) compared with neonates (72%), adults (71%) and elderly (70%). Conclusions Our prospective, multicenter surveillance study showed a low incidence of candidemia in Chile, with high 30-day survival, a large proportion of elderly patients, C. glabrata as the third most commonly identified strain, a 6.6% resistance to antifungal agents and a frequent use of echinocandins.Item Differential antifungal activity of human and cryptococcal melanins with structural discrepancies(Frontiers Research Foundation, 2017) Correa Leiva, Néstor; Covarrubias, Cristian; Rodas, Paula; Hermosilla, German; Olate, Veronica; Valdes, Cristian; Meyer, Wieland; Magne, Fabien; Tapia, CeciliaMelanin is a pigment found in all biological kingdoms, and plays a key role in protection against ultraviolet radiation, oxidizing agents, and ionizing radiation damage. Melanin exerts an antimicrobial activity against bacteria, fungi, and parasites. We demonstrated an antifungal activity of synthetic and human melanin against Candida sp. The members of the Cryptococcus neoformans and C. gattii species complexes are capsulated yeasts, which cause cryptococcosis. For both species melanin is an important virulence factor. To evaluate if cryptococcal and human melanins have antifungal activity against Cryptococcus species they both were assayed for their antifungal properties and physico-chemical characters. Melanin extracts from human hair and different strains of C. neoformans (n = 4) and C. gattii (n = 4) were investigated. The following minimum inhibitory concentrations were found for different melanins against C. neoformans and C. gattii were (average/range): 13.7/(7.8-15.6) and 19.5/(15.6-31.2) μg/mL, respectively, for human melanin; 273.4/(125->500) and 367.2/(125.5->500) μg/mL for C. neoformans melanin and 125/(62.5-250) and 156.2/(62-250) μg/mL for C. gattii melanin. Using Scanning Electron Microscopy we observed that human melanin showed a compact conformation and cryptococcal melanins exposed an amorphous conformation. Infrared spectroscopy (FTIR) showed some differences in the signals related to C-C bonds of the aromatic ring of the melanin monomers. High Performance Liquid Chromatography established differences in the chromatograms of fungal melanins extracts in comparison with human and synthetic melanin, particularly in the retention time of the main compound of fungal melanin extracts and also in the presence of minor unknown compounds. On the other hand, MALDI-TOF-MS analysis showed slight differences in the spectra, specifically the presence of a minor intensity ion in synthetic and human melanin, as well as in some fungal melanin extracts. We conclude that human melanin is more active than the two fungal melanins against Cryptococcus. Although some physico-chemical differences were found, they do not explain the differences in the antifungal activity against Cryptococcus of human and cryptococcal melanins. More detailed studies on the structure should be considered to associate structure and antifungal activity.Item Melanocytes and melanin represent a first line of innate immunity against Candida albicans(International Society for Human and Animal Mycology, 2014) Tapia, Cecilia; Falconer, Maryanne; Tempio, Fabián; Falcón, Felipe; López, Mercedes; Fuentes, Marisol; Alburquenque, Claudio; Amaro, José; Bucarey, Sergio; Di Nardo, AnnaMelanocytes are dendritic cells located in the skin and mucosae that synthesize melanin. Some infections induce hypo- or hyperpigmentation, which is associated with the activation of Toll-like receptors (TLRs), especially TLR4. Candida albicans is an opportunist pathogen that can switch between blastoconidia and hyphae forms; the latter is associated with invasion. Our objectives in this study were to ascertain whether C. albicans induces pigmentation in melanocytes and whether this process is dependent on TLR activation, as well as relating this with the antifungal activity of melanin as a first line of innate immunity against fungal infections. Normal human melanocytes were stimulated with C. albicans supernatants or with crude extracts of the blastoconidia or hyphae forms, and pigmentation and TLR2/TLR4 expression were measured. Expression of the melanosomal antigens Melan-A and gp100 was examined for any correlation with increased melanin levels or antifungal activity in melanocyte lysates. Melanosomal antigens were induced earlier than cell pigmentation, and hyphae induced stronger melanization than blastoconidia. Notably, when melanocytes were stimulated with crude extracts of C. albicans, the cell surface expression of TLR2/TLR4 began at 48 h post-stimulation and peaked at 72 h. At this time, blastoconidia induced both TLR2 and TLR4 expression, whereas hyphae only induced TLR4 expression. Taken together, these results suggest that melanocytes play a key role in innate immune responses against C. albicans infections by recognizing pathogenic forms of C. albicans via TLR4, resulting in increased melanin content and inhibition of infection.Publication Validation of real-time PCR as a diagnostic tool in aspergillosis associated with COVID-19 in patients hospitalized at Clínica Dávila at Santiago, Chile, during the years 2020 and 2021(2023) Fellay, Simone; Pino, Roberto; Hardy, Megan; Tapia, CeciliaIntroducción: Desde el inicio de la pandemia por COVID-19 se han registrado casos de infecciones de aspergilosis pulmonar asociada a esta infección, la cual tiene características diferentes a la aspergilosis pulmonar clásica y, por lo tanto, han significado un desafío diagnóstico. Objetivo: Validar una reacción de polimerasa en cadena (RPC) en tiempo real (sigla en inglés RT-PCR) comercial, como herramienta diagnóstica alternativa a la técnica de galactomanano (GM) en el diagnóstico de aspergilosis pulmonar asociada a COVID-19 (sigla en inglés CAPA). Pacientes y Método: Se analizaron resultados de RT-PCR de Aspergillus spp y GM en lavado bronco-alveolar (LBA) de 72 pacientes, hospitalizados por COVID-19 de Clínica Dávila entre los años 2020 y 2021. De estos pacientes, 33 presentaron CAPA. Resultados: La RT-PCR de Aspergillus y GM presentaron una correlación positiva (r = 0,6351, valor p < 0,0001). La técnica de RT-PCR presentó una sensibilidad (S), especificidad (E), valor predictor positivo (VPP) y valor predictor negativo (VPN) de 100, 44, 66 y 100%, respectivamente, mientras que en GM fueron de 64, 89, 84 y 73%, respectivamente para LBA. Al utilizar ambas técnicas en combinación se obtuvo una S, E, VPP y VPN de 100, 82, 88 y 100%, respectivamente. Conclusión: Este estudio concluyó que usar una técnica de RT-PCR de Aspergillus y GM en conjunto en LBA mejoraron los parámetros de desempeño de ambas técnicas usadas de manera individual para diagnosticar CAPA. Se requieren más estudios para evaluar el desempeño de técnicas combinadas en otros tipos de aspergilosis. Background: Since the beginning of the COVID-19 pandemic, there have been cases of pulmonary aspergillosis infections associated with this infection, which has different characteristics from classical pulmonary aspergillosis and therefore, have been diagnostic challenges. Aim: To validate a commercial real-time PCR (RT-PCR) method as an alternative diagnostic tool to the galactomannan (GM) technique in the diagnosis of COVID-19-associated pulmonary aspergillosis (CAPA). Methods: Results of RT-PCR of Aspergillus spp and GM in broncho-alveolar lavage (BAL) of 72 patients hospitalized for COVID-19 at Clínica Dávila between 2020 and 2021 were analyzed. Of these patients, 33 presented CAPA. Results: The RT-PCR for Aspergillus and GM showed a positive correlation (r = 0.6351, p-value < 0.0001). The RT-PCR for Aspergillus technique presented a sensitivity (S), specificity (S), positive predictive value (PPV) and negative predictive value (NPV) of 100, 44, 66 and 100% respectively, while the GM technique presented 64, 89, 84 and 73%, respectively for BAL. Using both techniques in combination a S, E, PPV and NPV of 100, 82, 88 and 100% were obtained respectively. Conclusion: This study concluded that using RT-PCR and GM techniques in combination in BAL improved the performance parameters of both techniques from those used individually to diagnose CAPA. Further studies are required to evaluate the performance of combined techniques in other aspergillosis focus.