A comparative in vitro photoinactivation study of clinical isolates of multidrug-resistant pathogens

Tang, Hi M.; Hamblin, Michael R.; Yow, Cmn

doi:10.1007/s10156-006-0501-8

Cited by 95 publications

(51 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This is in agreement with the outcomes of a previous study from our group on APDT using VIS ϩ wIRA, in which successful outcomes were achieved against initially (2 h) in situadherent bacteria at even lower TB concentrations of up to 10 g ml Ϫ2 (20). Similarly, encouraging APDT-induced CFU reduction was observed in numerous in vitro studies with various other light sources and photosensitizers (42)(43)(44)(45). Regarding oral pathogenic bacteria in particular, the posttreatment decrease in viable bacterial counts has also been confirmed in several in vitro studies to date (28,(46)(47)(48)(49).…”

Section: Discussionsupporting

confidence: 91%

Novel Broad-Spectrum Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light plus Water-Filtered Infrared A

Karygianni

Ruf

Follo

et al. 2014

Appl Environ Microbiol

View full text Add to dashboard Cite

Antimicrobial photodynamic therapy (APDT) has gained increased attention as an alternative treatment approach in various medical fields. However, the effect of APDT using visible light plus water-filtered infrared A (VIS ؉ wIRA) on oral biofilms remains unexplored. For this purpose, initial and mature oral biofilms were obtained in situ; six healthy subjects wore individual upper jaw acrylic devices with bovine enamel slabs attached to their proximal sites for 2 h or 3 days. The biofilms were incubated with 100 g ml ؊1 toluidine blue O (TB) or chlorin e6 (Ce6) and irradiated with VIS ؉ wIRA with an energy density of 200 mW cm ؊2 for 5 min. After cultivation, the CFU of half of the treated biofilm samples were quantified, whereas following live/dead staining, the other half of the samples were monitored by confocal laser scanning microscopy (CLSM). TB-and Ce6-mediated APDT yielded a significant decrease of up to 3.8 and 5.7 log 10 CFU for initial and mature oral biofilms, respectively. Quantification of the stained photoinactivated microorganisms confirmed these results. Overall, CLSM revealed the diffusion of the tested photosensitizers into the deepest biofilm layers after exposure to APDT. In particular, Ce6-aided APDT presented elevated permeability and higher effectiveness in eradicating 89.62% of biofilm bacteria compared to TB-aided APDT (82.25%) after 3 days. In conclusion, antimicrobial photoinactivation using VIS ؉ wIRA proved highly potent in eradicating oral biofilms. Since APDT excludes the development of microbial resistance, it could supplement the pharmaceutical treatment of periodontitis or peri-implantitis.

show abstract

Section: Discussionsupporting

confidence: 91%

Novel Broad-Spectrum Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light plus Water-Filtered Infrared A

Karygianni

Ruf

Follo

et al. 2014

Appl Environ Microbiol

View full text Add to dashboard Cite

show abstract

“…A number of studies have shown that TBO is phototoxic to several planktonic gram-positive and gram-negative bacteria (10,22,24). The photodynamic efficacy of TBO has also been demonstrated in several oral biofilm models (30,31).…”

Section: Discussionmentioning

confidence: 99%

“…The resulting photochemical reactions generate cytotoxic reactive oxygen species, such as singlet oxygen and free radicals, which are able to exert bactericidal effect. Several studies have reported on the photodynamic inactivation of gram-positive and gram-negative bacteria in planktonic cultures using different photosensitizing drugs (16,22,23,25). Although PDT is being actively investigated for the eradication of bacterial biofilms growing in dental plaques and on oral implants (26,27,28), there are very few studies on the effect of PDT on staphylococcal biofilms.…”

mentioning

confidence: 99%

Toluidine Blue-Mediated Photodynamic Effects on Staphylococcal Biofilms

Sharma

Visai²,

Bragheri

et al. 2008

Antimicrob Agents Chemother

164

View full text Add to dashboard Cite

Staphylococci are important causes of nosocomial and medical-device-related infections. Their virulence is attributed to the elaboration of biofilms that protect the organisms from immune system clearance and to increased resistance to phagocytosis and antibiotics. Photodynamic treatment (PDT) has been proposed as an alternative approach for the inactivation of bacteria in biofilms. In this study, we have investigated the effect of the photodynamic action of toluidine blue O (TBO) on the viability and structure of biofilms of Staphylococcus epidermidis and of a methicillin-resistant Staphylococcus aureus strain. Significant inactivation of cells was observed when staphylococcal biofilms were exposed to TBO and laser simultaneously. The effect was found to be light dose dependent. Confocal laser scanning microscopic study suggested damage to bacterial cell membranes in photodynamically treated biofilms. In addition, scanning electron microscopy provided direct evidence for the disruption of biofilm structure and a decrease in cell numbers in photodynamically treated biofilms. Furthermore, the treatment of biofilms with tetrasodium EDTA followed by PDT enhanced the photodynamic efficacy of TBO in S. epidermidis, but not in S. aureus, biofilms. The results suggest that photodynamic treatment may be a useful approach for the inactivation of staphylococcal biofilms adhering to solid surfaces of medical implants.

show abstract

“…Depending on the effectiveness of the antimicrobial photosensitizer, up to three logs of bacterial or fungal cells can be killed without causing unacceptable damage to the host tissue (11). PDI is thought to be equally effective against multidrug-resistant and naïve species (49), and in addition the PDI treatment itself is unlikely to cause resistance to arise (26). It should be noted that the lack of development of resistance after PDT is generally difficult to prove experimentally but can be shown in particular instances.…”

mentioning

confidence: 99%

Stable Synthetic Cationic Bacteriochlorins as Selective Antimicrobial Photosensitizers

Huang

Mróz

et al. 2010

Antimicrob Agents Chemother

Self Cite

120

112

View full text Add to dashboard Cite

Photodynamic inactivation is a rapidly developing antimicrobial treatment that employs a nontoxic photoactivatable dye or photosensitizer in combination with harmless visible light to generate reactive oxygen species that are toxic to cells. Tetrapyrroles (e.g., porphyrins, chlorins, bacteriochlorins) are a class of photosensitizers that exhibit promising characteristics to serve as broad-spectrum antimicrobials. In order to bind to and efficiently penetrate into all classes of microbial cells, tetrapyrroles should have structures that contain (i) one or more cationic charge(s) or (ii) a basic group. In this report, we investigate the use of new stable synthetic bacteriochlorins that have a strong absorption band in the range 720 to 740 nm, which is in the near-infrared spectral region. Four bacteriochlorins with 2, 4, or 6 quaternized ammonium groups or 2 basic amine groups were compared for light-mediated killing against a Gram-positive bacterium (Staphylococcus aureus), a Gramnegative bacterium (Escherichia coli), and a dimorphic fungal yeast (Candida albicans). Selectivity was assessed by determining phototoxicity against human HeLa cancer cells under the same conditions. All four compounds were highly active (6 logs of killing at 1 M or less) against S. aureus and showed selectivity for bacteria over human cells. Increasing the cationic charge increased activity against E. coli. Only the compound with basic groups was highly active against C. albicans. Supporting photochemical and theoretical characterization studies indicate that (i) the four bacteriochlorins have comparable photophysical features in homogeneous solution and (ii) the anticipated redox characteristics do not correlate with cell-killing ability. These results support the interpretation that the disparate biological activities observed stem from cellular binding and localization effects rather than intrinsic electronic properties. These findings further establish cationic bacteriochlorins as extremely active and selective near-infrared activated antimicrobial photosensitizers, and the results provide fundamental information on structure-activity relationships for antimicrobial photosensitizers.

show abstract

A comparative in vitro photoinactivation study of clinical isolates of multidrug-resistant pathogens

Cited by 95 publications

References 23 publications

Novel Broad-Spectrum Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light plus Water-Filtered Infrared A

Novel Broad-Spectrum Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light plus Water-Filtered Infrared A

Toluidine Blue-Mediated Photodynamic Effects on Staphylococcal Biofilms

Stable Synthetic Cationic Bacteriochlorins as Selective Antimicrobial Photosensitizers

Contact Info

Product

Resources

About