Degree: Doctor
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Showing 5 latest publications. Total publications: 51
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1.
Visible-light photoactivated proanthocyanidin and kappa-carrageenan coating with anti-adhesive properties against clinically relevant bacteria,
in INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES, 2024, ISSN: 0141-8130, Volume: 263,
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1016/j.ijbiomac.2024.130611 P-010-4YH
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1016/j.ijbiomac.2024.130611 P-010-4YH
Abstract
The increase of bacterial resistance to antibiotics is a growing concern worldwide and the search for new therapies could cost billions of dollars and countless lives. Inert surfaces are major sources of contamination due to easier adhesion and formation of bacterial biofilms, hindering the disinfection process. Therefore, the objective of this study was to develop a photoactivatable and anti-adhesive kappa-carrageenan coating using proanthocyanidin as a photosensitizer. The complete reduction (>5-log(10) CFU/cm(3)) of culturable cells of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa pathogens was achieved after 30 min of exposure to visible light (420 nm; 30 mW/cm(2)) with 5 % (w/v) of the photosensitizer. Cell membrane damage was confirmed by measuring potassium leakage, epifluorescence microscopy and bacterial motility analysis. Overall, visible light irradiation on coated solid surfaces mediated by proanthocyanidin showed no cytotoxicity and inactivated clinically important pathogens through the generation of reactive oxygen species, inhibiting bacterial initial adhesion. The developed coating is a promising alternative for a wide range of applications related to surface disinfection and food biopreservation.
2.
Dual action of benzaldehydes: Inhibiting quorum sensing and enhancing antibiotic efficacy for controlling Pseudomonas aeruginosa biofilms,
in MICROBIAL PATHOGENESIS, 2024, ISSN: 0882-4010, Volume: 191,
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1016/j.micpath.2024.106663 P-010-D34
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1016/j.micpath.2024.106663 P-010-D34
Abstract
Quorum sensing (QS) has a central role in biofilm lifestyle and antimicrobial resistance, and disrupting these signaling pathways is a promising strategy to control bacterial pathogenicity and virulence. In this study, the efficacy of three structurally related benzaldehydes (4-hydroxybenzaldehyde, 4-hydroxy-3-methoxybenzaldehyde (vanillin) and 4-hydroxy-3,5-dimethoxybenzaldehyde (syringaldehyde)) in disrupting the las and pqs systems of Pseudomonas aeruginosa was investigated using bioreporter strains and computational simulations. Additionally, these benzaldehydes were combined with tobramycin and ciprofloxacin antibiotics to evaluate their ability to increase antibiotic efficacy in preventing and eradicating P. aeruginosa biofilms. To this end, the total biomass, metabolic activity and culturability of the biofilm cells were determined. In vitro assays results indicated that the aromatic aldehydes have potential to inhibit the las and pqs systems by > 80 %. Molecular docking studies supported these findings, revealing the aldehydes binding in the same pocket as the natural ligands or receptor proteins (LasR, PQSA, PQSE, PQSR). Benzaldehydes were shown to act as virulence factor attenuators, with vanillin achieving a 48 % reduction in pyocyanin production. The benzaldehyde-tobramycin combination led not only to a 60 % reduction in biomass production but also to a 90 % reduction in the metabolic activity of established biofilms. A similar result was observed when benzaldehydes were combined with ciprofloxacin. 4-Hydroxybenzaldehyde demonstrated relevant action in increasing biofilm susceptibility to ciprofloxacin, resulting in a 65 % reduction in biomass. This study discloses, for the first time, that the benzaldehydes studied are potent QS inhibitors and also enhancers of antibiotics antibiofilm activity against P. aeruginosa.
3.
Photodynamic activation of phytochemical-antibiotic combinations for combatting Staphylococcus aureus from acute wound infections,
in JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY, 2024, ISSN: 1011-1344, Volume: 258,
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1016/j.jphotobiol.2024.112978 P-010-XYE
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1016/j.jphotobiol.2024.112978 P-010-XYE
Abstract
Staphylococcus aureus is characterized by its high resistance to conventional antibiotics, particularly methicillinresistant (MRSA) strains, making it a predominant pathogen in acute and chronic wound infections. The persistence of acute S. aureus wound infections poses a threat by increasing the incidence of their chronicity. This study investigated the potential of photodynamic activation using phytochemical-antibiotic combinations to eliminate S. aureus under conditions representative of acute wound infections, aiming to mitigate the risk of chronicity. The strategy applied takes advantage of the promising antibacterial and photosensitising properties of phytochemicals, and their ability to act as antibiotic adjuvants. The antibacterial activity of selected phytochemicals (berberine, curcumin, farnesol, gallic acid, and quercetin; 6.25 - 1000 mu g/mL) and antibiotics (ciprofloxacin, tetracycline, fusidic acid, oxacillin, gentamicin, mupirocin, methicillin, and tobramycin; 0.0625 - 1024 mu g/mL) was screened individually and in combination against two S. aureus clinical strains (methicillin-resistant and-susceptible - MRSA and MSSA). The photodynamic activity of the phytochemicals was assessed using a lightemitting diode (LED) system with blue (420 nm) or UV-A (365 nm) variants, at 30 mW/cm 2 (light doses of 9, 18, 27 J/cm 2 ) and 5.5 mW/cm 2 (light doses of 1.5, 3.3 and 5.0 J/cm 2 ), respectively. Notably, all phytochemicals restored antibiotic activity, with 9 and 13 combinations exhibiting potentiating effects on MSSA and MRSA, respectively. Photodynamic activation with blue light (420 nm) resulted in an 8- to 80-fold reduction in the bactericidal concentration of berberine against MSSA and MRSA, while curcumin caused 80-fold reduction for both strains at the light dose of 18 J/cm 2 . Berberine and curcumin-antibiotic combinations when subjected to photodynamic activation (420 nm light, 10 min, 18 J/cm 2 ) reduced S. aureus culturability by approximate to 9 log CFU/mL. These combinations lowered the bactericidal concentration of antibiotics, achieving a 2048-fold reduction for gentamicin and 512-fold reduction for tobramycin. Overall, the dual approach involving antimicrobial photodynamic inactivation and selected phytochemical-antibiotic combinations demonstrated a synergistic effect, drastically reducing the culturability of S. aureus and restoring the activity of gentamicin and tobramycin.
4.
Antimicrobial cyclodextrin-assisted electrospun fibers loaded with carvacrol, citronellol and cinnamic acid for wound healing,
in INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES, 2024, ISSN: 0141-8130, Volume: 277,
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1016/j.ijbiomac.2024.134154 P-016-SR7
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1016/j.ijbiomac.2024.134154 P-016-SR7
Abstract
This work aimed to explore an alternative to the use of antibiotics for prevention and treatment of wounds infection caused by two common bacterial pathogens Staphylococcus aureus and Pseudomonas aeruginosa. For this purpose, three different essential oil components (EOCs), namely carvacrol, citronellol and cinnamic acid, were loaded into electrospun fibers of poly-epsilon-caprolactone (PCL) aided by alpha-cyclodextrin (alpha CD) and hydroxypropyl-beta-cyclodextrin (HP beta CD). Electrospun-fibers prepared with each EOC and their mixtures were screened for antimicrobial capability and characterized regarding morphological, mechanical, thermal, surface polarity, antibiofilm and antioxidant properties. alpha CD formed poly(pseudo)rotaxanes with PCL and weakly interacted with EOCs, while HP beta CD facilitated EOC encapsulation and formation of homogeneous fibers (500-1000 nm diameter) without beads. PCL/HP beta CD fibers with high concentration of EOCs (mainly carvacrol and cinnamic acid) showed strong antibiofilm (>3 log CFU reduction) and antioxidant activity (10-50% DPPH scavenging effects). Different performances were recorded for the EOCs and their mixtures; cinnamic acid migrated to fiber surface and was released faster. Fibers biocompatibility was verified using hemolysis tests and in ovo tissue integration and angiogenesis assays. Overall, HP beta CD facilitates complete release of EOCs from the fibers to the aqueous medium, being an environment-friendly and cost-effective strategy for the treatment of infected wounds.
5.
A procedure to harmonize the hydrodynamic force during microbial cultivation in shaking flasks,
in JOURNAL OF MICROBIOLOGY & BIOLOGY EDUCATION, 2023, ISSN: 1935-7877, Volume: 24,
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1128/jmbe.00099-23 P-00Z-8X1
Article, Indexed in: crossref, scopus, unpaywall, wos DOI: 10.1128/jmbe.00099-23 P-00Z-8X1
Abstract
Shake flask cultivation is a routine technique in microbiology and biotechnology laboratories where cell growth can be affected by the hydrodynamic conditions, which depend on the agitation velocity, shaking diameter, and shake flask size. Liquid agitation is implemented inherently to increase aeration, substrate transfer to the cells, and prevent sedimentation, disregarding the role of hydrodynamics in microbial growth and metabolism. Here, we present a simple approach to help standardize the hydrodynamic forces in orbital shakers to increase the experimental accuracy and reproducibility and give students a better knowledge of the significance of the agitation process in microbial growth.