Sublethal Photodynamic Treatment Does Not Lead to Development of Resistance.
Abstract
A promising new alternative approach for eradication of antibiotic-resistant strains
is to expose microbes to photosensitizers, which upon illumination generate reactive
oxygen species. Among the requirements for a potent, medically applicable photosensitizer,
are high efficacy in killing microbes and low toxicity to the host. Since photodynamic
treatment is based on production of reactive species which are potentially DNA damaging
and mutagenic, it might be expected that under selective pressure, microbes would
develop resistance. The aim of this study was to determine if antibacterial photodynamic
treatment with a highly photoefficient photosensitizer, Zn(II) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin
would lead to development of resistance. To answer that question, bacterial cultures
were subjected to multiple cycles of sublethal photodynamic stress and regrowth, and
to continuous growth under photodynamic exposure. Antibiotic-resistant Staphylococcus
aureus and Escherichia coli clinical isolates were also tested for susceptibility
to photodynamic inactivation and for development of resistance. Results demonstrated
that multiple photodynamic exposures and regrowth of surviving cells or continuous
growth under sublethal photodynamic conditions, did not lead to development of resistance
to photosensitizers or to antibiotics. Antibiotic-resistant E. coli and S. aureus
were as sensitive to photodynamic killing as were their antibiotic-sensitive counterparts
and no changes in their sensitivity to antibiotics or to photodynamic inactivation
after multiple cycles of photodynamic treatment and regrowth were observed. In conclusion,
photosensitizers with high photodynamic antimicrobial efficiency can be used successfully
for eradication of antibiotic-resistant bacterial strains without causing development
of resistance.
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https://hdl.handle.net/10161/21191Published Version (Please cite this version)
10.3389/fmicb.2018.01699Publication Info
Al-Mutairi, Rawan; Tovmasyan, Artak; Batinic-Haberle, Ines; & Benov, Ludmil (2018). Sublethal Photodynamic Treatment Does Not Lead to Development of Resistance. Frontiers in microbiology, 9. pp. 1699. 10.3389/fmicb.2018.01699. Retrieved from https://hdl.handle.net/10161/21191.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Ines Batinic-Haberle
Professor Emeritus of Radiation Oncology
A major interest of mine has been in the design and synthesis of Mn porphyrin(MnP)-based
powerful catalytic antioxidants which helped establish structure-activity relationship
(SAR). It relates the redox property of metalloporphyrins to their ability to remove
superoxide. SAR has facilitated the design of redox-active therapeutics and served
as a tool for mechanistic considerations. Importantly SAR parallels the magnitu

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