Antimicrobial susceptibility of photodynamic therapy (UVA/riboflavin) against Staphylococcus aureus

Kashiwabuchi, Renata T.; Khan, Yasín A.; Carvalho, Fábio Ramos de Souza; Hirai, Flávio E.; Campos, Mauro; McDonnell, Peter J.

doi:10.1590/s0004-27492012000600011

Cited by 18 publications

(11 citation statements)

References 23 publications

(18 reference statements)

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“…Among the B vitamins riboflavin exhibits the highest quantum yield of singlet oxygen generation (Φ Δ = 0.54) [22] , [34] , which should be in principle sufficient to inactivate microorganisms via PIB. However, the use of light activated riboflavin showed hardly any bacterial killing effects [35] , [36] . This is not surprising because such uncharged molecules cannot attach to the cell wall of bacteria and hence yield no or minimal antimicrobial effect [37] .…”

Section: Discussionmentioning

confidence: 99%

Fast and Effective Photodynamic Inactivation of Multiresistant Bacteria by Cationic Riboflavin Derivatives

et al. 2014

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Photodynamic inactivation of bacteria (PIB) proves to be an additional method to kill pathogenic bacteria. PIB requires photosensitizer molecules that effectively generate reactive oxygen species like singlet oxygen when exposed to visible light. To allow a broad application in medicine, photosensitizers should be safe when applied in humans. Substances like vitamin B2, which are most likely safe, are known to produce singlet oxygen upon irradiation. In the present study, we added positive charges to flavin derivatives to enable attachment of these molecules to the negatively charged surface of bacteria. Two of the synthesized flavin derivatives showed a high quantum yield of singlet oxygen of approximately 75%. Multidrug resistant bacteria like MRSA (Methicillin resistant Staphylococcus aureus), EHEC (enterohemorrhagic Escherichia coli), Pseudomonas aeruginosa, and Acinetobacter baumannii were incubated with these flavin derivatives in vitro and were subsequently irradiated with visible light for seconds only. Singlet oxygen production in bacteria was proved by detecting its luminescence at 1270 nm. After irradiation, the number of viable bacteria decreased up to 6 log10 steps depending on the concentration of the flavin derivatives and the light dosimetry. The bactericidal effect of PIB was independent of the bacterial type and the corresponding antibiotic resistance pattern. In contrast, the photosensitizer concentration and light parameters used for bacteria killing did not affect cell viability of human keratinocytes (therapeutic window). Multiresistant bacteria can be safely and effectively killed by a combination of modified vitamin B2 molecules, oxygen and visible light, whereas normal skin cells survive. Further work will include these new photosensitizers for topical application to decolonize bacteria from skin and mucosa.

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Section: Discussionmentioning

confidence: 99%

Fast and Effective Photodynamic Inactivation of Multiresistant Bacteria by Cationic Riboflavin Derivatives

et al. 2014

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“…UV-C irradiation represents an effective procedure for the inactivation of bio-contamination. It eliminates viruses and bacteria, and it is frequently used for the disinfection of materials sensitive to high temperatures or materials that cannot be treated with chemically active substances [28]. This method has been used successfully for superficial sterilization in the biopharmaceutical industry [29] or in post-harvest crop protection [30,31].…”

Section: Resultsmentioning

confidence: 99%

Establishing an efficient explant superficial sterilization protocol for in vitro micropropagation of bear’s garlic (Allium ursinum L.)

et al. 2015

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SummaryIntroduction:Allium ursinumL. has a commercial value due to its high contents of bio-active compounds and mild, garlic-like taste.In vitroculture played an important role in obtainingAlliumspecies with the desired characteristics and in the production of healthy reproductive material.Objective:Developing an effective method of sterilization bear’s garlic bulbs.Methods:To obtain sterile shoots of garlic several methods of sterilization involving such factors as ACE, H2O2, HgCl2, and UV-C were tested.Results:In order to obtain sterile shoots of bear’s garlic, several sterilization procedures were tested. The best procedure was based on a two-step disinfection, where the whole onions were treated with ethanol and H2O2for 20 min. Thereafter, the isolated apical buds were sterilized in ACE for 10 min, rinsed in double-distilled water and transferred onto MS medium for growing. Up to 95% of the inoculated explants formed shoots, which were sub-cultured on MS with 4 mg dm−3BAP in order to enable further propagation.Conclusion:After optimization and stabilization, this procedure may become the basic concept of a proper and reliable propagation method of bear’s garlic on commercial scale.

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“…42 Despite sufficient singlet oxygen generation, riboflavin shows a poor antibacterial killing efficacy. 43,44 This is because riboflavin is an uncharged molecule and cannot attach well to the negatively charged surface of microorganisms. Thus, an efficient photosensitizer should be positively charged to allow the attachment to negatively charged cell walls.…”

Section: Discussionmentioning

confidence: 99%

Fast and effective inactivation of Bacillus atrophaeus endospores using light-activated derivatives of vitamin B2

Eichner

Gollmer

Späth

et al. 2015

Photochem Photobiol Sci

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Highly resistant endospores may cause severe problems in medicine as well as in the food and packaging industries. We found that bacterial endospores can be inactivated quickly with reactive oxygen species (ROS) that were generated by a new generation of flavin photosensitizers. Flavins like the natural compound vitamin B2 are already known to produce ROS but they show a poor antimicrobial photodynamic killing efficacy due to the lack of positive charges. Therefore we synthesized new flavin photosensitizers that have one (FLASH-01a) or eight (FLASH-07a) positive charges and can hence attach to the negatively charged surface of endospores. In this study we used standardized Bacillus atrophaeus endospores (ATCC 9372) as a biological surrogate model for a proof-of-concept study of photodynamic inactivation experiments using FLASH-01a and FLASH-07a. After incubation of spores with different flavin concentrations, the flavin derivatives were excited with blue light at a light dose of 70 J cm(-2). The inactivation of spores was investigated either in suspension or after attachment to polyethylene terephthalate (PET) surfaces. Incubation of spores suspended in Millipore water with 4 mM FLASH-01a for 10 seconds and irradiation with blue light for 10 seconds caused a biologically relevant decrease of spore survival of 3.5 log10 orders. Using FLASH-07a under the same conditions we achieved a decrease of 4.4 log10 orders. Immobilized spores on PET surfaces were efficiently killed with 7.0 log10 orders using 8 mM FLASH-07a. The total treatment time (incubation + irradiation) was as short as 20 seconds. The results of this study show evidence that endospores can be fastly and effectively inactivated with new generations of flavin photosensitizers that may be useful for industrial or medical applications in the future.

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Antimicrobial susceptibility of photodynamic therapy (UVA/riboflavin) against Staphylococcus aureus

Cited by 18 publications

References 23 publications

Fast and Effective Photodynamic Inactivation of Multiresistant Bacteria by Cationic Riboflavin Derivatives

Fast and Effective Photodynamic Inactivation of Multiresistant Bacteria by Cationic Riboflavin Derivatives

Establishing an efficient explant superficial sterilization protocol for in vitro micropropagation of bear’s garlic (Allium ursinum L.)

Fast and effective inactivation of Bacillus atrophaeus endospores using light-activated derivatives of vitamin B2

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