Examinando por Autor "Silva, Víctor"
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Ítem Dermatophytosis caused by Trichophyton benhamiae in a sea lion. First report(Elsevier B.V., 2024-12) López, Ronar; Silva, Víctor; Bown, Viviana; Godoy-Martínez, Patricio; Thomson, PamelaFungal infections in marine animals, particularly pinnipeds, have seen a notable increase, often linked to compromised immune systems in captive environments. Trichophyton species, while common in terrestrial mammals, have sporadically caused dermatophytosis in pinnipeds. A South American sea lion (Otaria byronia) presented with Trichophyton benhamiae infection, marking the first such case in this species. Effective treatment combined oral terbinafine with topical ozonized oil, supported by silymarin for liver protection. Accurate fungal identification and sensitivity testing were key to the successful management and recovery of the patient. © 2024Ítem Drimane Sesquiterpene Alcohols with Activity against Candida Yeast Obtained by Biotransformation with Cladosporium antarcticum(MDPI, 2022-11) Cortez, Nicole; Marín, Víctor; Jiménez, Verónica A.; Silva, Víctor; Leyton, Oscar; Cabrera Pardo, Jaime R.; Schmidt, Bernd; Heydenreich, Matthias; Burgos, Viviana; Duran, Paola; Paz, CristianFungal biotransformation is an attractive synthetic strategy to produce highly specific compounds with chemical functionality in regions of the carbon skeleton that are not easily activated by conventional organic chemistry methods. In this work, Cladosporium antarcticum isolated from sediments of Glacier Collins in Antarctica was used to obtain novel drimane sesquiterpenoids alcohols with activity against Candida yeast from drimendiol and epidrimendiol. These compounds were produced by the high-yield reduction of polygodial and isotadeonal with NaBH4 in methanol. Cladosporium antarcticum produced two major products from drimendiol, identified as 9α-hydroxydrimendiol (1, 41.4 mg, 19.4% yield) and 3β-hydroxydrimendiol (2, 74.8 mg, 35% yield), whereas the biotransformation of epidrimendiol yielded only one product, 9β-hydroxyepidrimendiol (3, 86.6 mg, 41.6% yield). The products were purified by column chromatography and their structure elucidated by NMR and MS. The antifungal activity of compounds 1–3 was analyzed against Candida albicans, C. krusei and C. parapsilosis, showing that compound 2 has a MIC lower than 15 µg/mL against the three-pathogenic yeast. In silico studies suggest that a possible mechanism of action for the novel compounds is the inhibition of the enzyme lanosterol 14α-demethylase, affecting the ergosterol synthesis. © 2022 by the authors.Ítem Drimane Sesquiterpene Aldehydes Control Candida Yeast Isolated from Candidemia in Chilean Patients(MDPI, 2022-10) Marín, Víctor; Bart, Bryan; Cortez, Nicole; Jiménez, Verónica A.; Silva, Víctor; Leyton, Oscar; Cabrera Pardo, Jaime R.; Schmidt, Bernd; Heydenreich, Matthias; Burgos, Viviana; Paz, CristianDrimys winteri J.R. (Winteraceae) produce drimane sesquiterpenoids with activity against Candida yeast. In this work, drimenol, polygodial (1), isotadeonal (2), and a new drimane α,β-unsaturated 1,4-dialdehyde, named winterdial (4), were purified from barks of D. winteri. The oxidation of drimenol produced the monoaldehyde drimenal (3). These four aldehyde sesquiterpenoids were evaluated against six Candida species isolated from candidemia patients in Chilean hospitals. Results showed that 1 displays fungistatic activity against all yeasts (3.75 to 15.0 µg/mL), but irritant effects on eyes and skin, whereas its non-pungent epimer 2 has fungistatic and fungicide activities at 1.9 and 15.0 µg/mL, respectively. On the other hand, compounds 3 and 4 were less active. Molecular dynamics simulations suggested that compounds 1–4 are capable of binding to the catalytic pocket of lanosterol 14-alpha demethylase with similar binding free energies, thus suggesting a potential mechanism of action through the inhibition of ergosterol synthesis. According to our findings, compound 2 appears as a valuable molecular scaffold to pursue the future development of more potent drugs against candidiasis with fewer side effects than polygodial. These outcomes are significant to broaden the alternatives to treat fungal infections with increasing prevalence worldwide using natural compounds as a primary source for active compounds. © 2022 by the authors.Ítem Prevalencia y perfil de susceptibilidad antimicrobiana en bacterias aisladas de úlceras crònicas infectadas en adultos(Sociedad Chilena de Infectologia, 2018-04) Silva, Víctor; Marcoleta, Alicia; Silva, Viviana; Flores, Dángelo; Aparicio, Teresa; Aburto, Isabel; Latrach, Cecilia; Febré, NaldyBackground: Chronic wounds are considered a public health problem that may be complicated by bacterial infections, mainly caused by resistant strains. Aim: To study the bacteria prevalence and antimicrobial susceptibility in samples from adult patients with chronic wounds. Methods: Patients treated at National Institute of Wounds Foundation between May and July 2014, with chronic ulcers in lower extremities with clinical inflammatory signs were recluted. Samples were cultured in aerobic and anaerobic atmosphere and species identification was performed by API (Biomerieux) galleries. The in vitro susceptibility was evaluated according to the Kirby Bauer method. Results: From 73 patients, 46 had infected wounds most of them were venous ulcers (33) with prevalence in polymicrobial infections and 10 with foot-diabetes ulcers with prevalence in monomicrobial infections (p . 0.05). Sixty-eight strains were isolated and Enterobacteriaceae were predominant in monomicrobial infection (p . 0.05) and the other groups were slightly higher in polymicrobial infection. The main species were Staphylococcus aureus (24%) followed by P. aeruginosa (18%). Fifty strains (77%) were resistant or multi-resistance. We emphasize resistance of S. aureus to ciprofloxacin (50%) and cefoxitin (37.5%), thus identifying resistance to methicillin in the community (CA-SAMR), all of which are sensitive to cotrimoxazole. Enterobacteria showed sensitivity to amikacin (95.5%), P. aeruginosa showed resistance to ciprofloxacin (33.3%) with high sensitivity to gentamicin (91.7%) and amikacin (83.3%), while Acinetobacter spp showed resistance to ciprofloxacin and ceftazidime in 60%, with 100% sensitivity to imipenem. 50% Streptococcus β hemolytic showed resistance to clindamycin and penicillin. Conclusion: These data provide epidemiological information on chronic wound infections, representing support for diagnosis, treatment and management of this pathology. © 2018, Sociedad Chilena de Infectologia. All rights reserved.