ABSTRACT
The emergence of multidrug-resistant bacteria is a growing problem and alternative therapies are being sought to effectively address this issue. The aim of this study is to assess a range of Escherichia coli strains' susceptibility to Methylene Blue-mediated antimicrobial photodynamic therapy and determine if this is affected by their antibiotic-resistance profile. Two reference and twenty-four uropathogenic clinical E. coli strains were used in this study. All were tested in vitro for antimicrobial susceptibility against sixteen antibiotics. Strains underwent photodynamic treatments using the photosensitizer Methylene Blue with red light and tested in both planktonic and biofilm state. It was found that reference strain ATCC 25922 was susceptible to all tested antibiotics whereas reference strain ATCC 35218 showed resistance only to Ampicillin. With the exception of strains number 16 and 22, all of the isolated strains were multidrug-resistant according to the criteria established by the European Centre for Disease Prevention and Control and the Centre for Disease Control and Prevention, where acquired non-susceptibility to at least one agent in three or more antimicrobial categories is outlined. Photodynamic therapy induced more than 3 log10 colony-forming units' reduction to all strains in planktonic state. Whereas when tested in biofilm state, two and a half times the original dose of methylene blue was necessary to cause a 3 log10 antimicrobial effect. There were statistically significant differences in susceptibility among the strains tested in both the planktonic and biofilm experiments. Nevertheless, antimicrobial photodynamic therapy could inactivate all multidrug-resistant strains in the planktonic and biofilm state.
ABSTRACT
Light-mediated killing of pathogens by cationic photosensitisers is a promising antimicrobial approach that avoids the development of resistance inherent to the use of antimicrobials. In this study, we demonstrate that modification of different photosensitisers with the triphenylphosphonium cation yields derivatives with excellent photoantimicrobial activity against Gram-positive bacteria (ie, Staphylococcus aureus and Enterococcus faecalis). Thus, the triphenylphosphonium functional group should be considered for the development of photoantimicrobials for the selective killing of Gram-positive bacteria in the presence of Gram-negative species.
Subject(s)
Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Organophosphorus Compounds/chemistry , Organophosphorus Compounds/pharmacology , Photochemotherapy , Photosensitizing Agents/chemistry , Photosensitizing Agents/pharmacology , Enterococcus faecalis/drug effects , Enterococcus faecalis/radiation effects , Escherichia coli/drug effects , Escherichia coli/radiation effects , Staphylococcus aureus/drug effects , Staphylococcus aureus/radiation effectsABSTRACT
Correction for 'Cationic phthalocyanine dendrimers as potential antimicrobial photosensitisers' by Rubén Ruiz-González et al., Org. Biomol. Chem., 2017, 15, 9008-9017.
ABSTRACT
In the present study we describe the synthesis, photophysical properties and the photoinactivation performance against representative microorganisms of two families of cationic dendrimeric phthalocyanines as potential photosensitisers. Four charged dendrimeric compounds varying in their degree of ionicity (4 or 8 positive charges) and the coordinating metal (zinc or ruthenium) are compared and assessed as potential photosensitising agents in terms of their antimicrobial activity.
Subject(s)
Antifungal Agents/pharmacology , Candida albicans/drug effects , Dendrimers/pharmacology , Escherichia coli/drug effects , Indoles/pharmacology , Photosensitizing Agents/pharmacology , Antifungal Agents/chemical synthesis , Antifungal Agents/chemistry , Cations/chemical synthesis , Cations/chemistry , Cations/pharmacology , Dendrimers/chemical synthesis , Dendrimers/chemistry , Dose-Response Relationship, Drug , Indoles/chemical synthesis , Indoles/chemistry , Isoindoles , Microbial Sensitivity Tests , Molecular Structure , Photosensitizing Agents/chemical synthesis , Photosensitizing Agents/chemistry , Structure-Activity RelationshipABSTRACT
A biocompatible fluorescent nanoprobe for singlet oxygen (1 O2 ) detection in biological systems was designed, synthesized, and characterized, that circumvents many of the limitations of the molecular probe Singlet Oxygen Sensor Green® (SOSG). This widely used commercial singlet oxygen probe was covalently linked to a polyacrylamide nanoparticle core using different architectures to optimize the response to 1 O2 . In contrast to its molecular counterpart, the optimum SOSG-based nanoprobe, which we call NanoSOSG, is readily internalized by E. coli cells and does not interact with bovine serum albumin. Furthermore, the spectral characteristics do not change inside cells, and the probe responds to intracellularly generated 1 O2 with an increase in fluorescence.
ABSTRACT
The development of photoactive and biocompatible nanostructures is a highly desirable goal to address the current threat of antibiotic resistance. Here, we describe a novel supramolecular biohybrid nanostructure based on the non-covalent immobilization of cationic zinc phthalocyanine (ZnPc) derivatives onto unmodified cellulose nanocrystals (CNC), following an easy and straightforward protocol, in which binding is driven by electrostatic interactions. These non-covalent biohybrids show strong photodynamic activity against S. aureus and E. coli, representative examples of Gram-positive and Gram-negative bacteria, respectively, and C. albicans, a representative opportunistic fungal pathogen, outperforming the free ZnPc counterparts and related nanosystems in which the photosensitizer is covalently linked to the CNC surface.
Subject(s)
Cellulose/chemistry , Indoles/chemistry , Nanoparticles/chemistry , Organometallic Compounds/chemistry , Photosensitizing Agents/chemistry , Candida albicans/drug effects , Cations/chemistry , Cryoelectron Microscopy , Dynamic Light Scattering , Escherichia coli/drug effects , Isoindoles , Light , Particle Size , Photosensitizing Agents/pharmacology , Staphylococcus aureus/drug effects , Zinc CompoundsABSTRACT
BACKGROUND: In clinical renal transplantation, an increase in proteinuria after conversion from calcineurin inhibitors to rapamycin has been reported. In contrast, there are studies showing a nephro-protective effect of rapamycin in proteinuric diseases characterized by progressive interstitial inflammatory fibrosis. METHODS: Because of the contradictory reports concerning rapamycin on proteinuria, we examined proteinuria and podocyte damage markers on two renal disease models, with clearly different pathophysiological mechanisms: a glomerular toxico-immunological model induced by puromycin aminonucleoside, and a chronic hyperfiltration and inflammatory model by mass reduction, both treated with a fixed high rapamycin dose. RESULTS: In puromycin groups, rapamycin provoked significant increases in proteinuria, together with a significant fall in podocin immunofluorescence, as well as clear additional damage to podocyte foot processes. Conversely, after mass reduction, rapamycin produced lower levels of proteinuria and amelioration of inflammatory and pro-fibrotic damage. In contrast to the puromycin model, higher glomerular podocin and nephrin expression and amelioration of glomerular ultrastructural damage were found. CONCLUSIONS: We conclude that rapamycin has dual opposing effects on subjacent renal lesion, with proteinuria and podocyte damage aggravation in the glomerular model and a nephro-protective effect in the chronic inflammatory tubulointerstitial model. Rapamycin produces slight alterations in podocyte structure when acting on healthy podocytes, but it clearly worsens those podocytes damaged by other concomitant injury.