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Browsing Microbiología by Subject "Actividad antimicrobiana"
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Item Evaluación de la actividad antimicrobiana de daptomicina asociada a nanopartículas de quitosano frente a Staphylococcus aureus(Universidad Santiago de Cali, 2025) Moncayo Chaves, Daniela; Bucheli Burgos, Linda Alexandra; Oñate Garzón, José Fernando (Director); Ciro Monsalve, Yhors Alexander (Director)Drug resistance is recognized as a global threat. Current methodologies fail to maintain adequate therapeutic concentrations, requiring higher doses and longer treatments, generating adverse effects. In this context, chitosan is a biopolymer that has emerged as a promising alternative for drug encapsulation because it has properties such as biocompatibility, biodegradability, mucoadhesiveness, antimicrobial activity and non-toxicity that make it suitable for use in the pharmaceutical sector. Daptomycin is a lipopeptide antibiotic used as a last resort to treat infections caused by Staphylococcus aureus, which range from skin conditions to serious diseases such as bacteremia and endocarditis. In this study, the synthesis, characterization and evaluation of the antimicrobial potential of chitosan nanoparticles loaded with daptomycin was carried out. To improve the efficacy of the antibiotic against S. aureus, the ionic gelation method was used with phytic acid as a cross-linking agent. This acid cross-links with the chitosan to encapsulate the daptomycin in chitosan nanoparticles, achieving an increase in the antimicrobial activity of the drug. The nanoparticles were characterized physicochemically, exhibiting a particle size of 453.9 ± 4.5 nm, Z potential of 29.4 ± 0.25 mV and a polydispersity index of 0.245 ± 0.03. The antimicrobial activity of the nanoparticles was evaluated against the S. aureus ATCC 25923 strain using the broth microdilution method. The minimum inhibitory concentration (MIC) of daptomycin was 64 μg/ml, while with nanoparticle encapsulation it was reduced to 4 μg/ml. In turn, the free nanoparticles presented antimicrobial activity at a chitosan concentration of 187.5 µg/mL. This study confirms the potential of chitosan nanoparticles to improve the effectiveness of the treatment of S. aureus infections.Item Identificación de péptidos aislados del caracol gigante africano (Achatina fulica) y estudio de su actividad antimicrobiana(Universidad Santiago de Cali, 2020) Martínez Esquivel, Richard Andrés; Varela Miranda, Rubén Eduardo (Director); Oñate Garzón, Jose Fernando (Director)Snails, due to their potential in bioprospecting, have been studied in different settings, one of which is obtaining peptides with therapeutic activity from African snail slime, since antitumor and cosmetic peptides have been identified in this species. The rapid spread of antibiotic-resistant microorganisms in recent decades and the poor development of new antimicrobial drugs has represented a significant public health problem worldwide. Therefore, it is necessary to look for alternatives for the design of new drugs, for example, antimicrobial peptides from snail slime type (PAMs). For the extraction of peptides from the African snail slime, the TRI Reagent®, reagent was used as a total protein extraction method, with a previous treatment with N-acetylcysteine for the elimination of the mucin present in the slime and thus improve the sample quality. Subsequently, the proteins extracted and filtered with AMICON were visualized with SDS gels with tricine at 14 and 16%, obtaining small bands mainly below 10 KDa, confirming the presence of peptides, despite this, the extract evaluated did not show antimicrobial activity. Finally, the data from the CIC (Cancer Research Center) of Spain also reported the isolation of peptides in the samples; however, its identification and synthesis are pending for the evaluation of its antimicrobial activity with pure peptides and in adequate concentrations. These results validate that the methodology used is appropriate for the isolation of peptides from the African snail slime in isolates from the city of Cali.