Different photodynamic effects of blue light with and without riboflavin on methicillin-resistant Staphylococcus aureus (MRSA) and human keratinocytes in vitro

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of infections in humans. Photodynamic therapy using blue light (450 nm) could possibly be used to reduce MRSA on different human tissue surfaces without killing the human cells. It could be less harmful than 300-400 nm light or common disinfectants. We applied blue light ± riboflavin (RF) to MRSA and keratinocytes, in an in vitro liquid layer model, and compared the effect to elimination using common disinfection fluids. MRSA dilutions (8 × 10 5 /mL) in wells were exposed to blue light (450 nm) ± RF at four separate doses (15, 30, 56, and 84 J/cm 2). Treated samples were cultivated on blood agar plates and the colony forming units (CFU) determined. Adherent human cells were cultivated (1 × 10 4 /mL) and treated in the same way. The cell activity was then measured by Cell Titer Blue assay after 24and 48-h growth. The tested disinfectants were chlorhexidine and hydrogen peroxide. Blue light alone (84 J/cm 2) eliminated 70% of MRSA. This dose and riboflavin eradicated 99-100% of MRSA. Keratinocytes were not affected by blue light alone at any dose. A dose of 30 J/cm 2 in riboflavin solution inactivated keratinocytes completely. Disinfectants inactivated all cells. Blue light alone at 450 nm can eliminate MRSAwithout inactivation of human keratinocytes. Hence, a high dose of blue light could perhaps be used to treat bacterial infections without loss of human skin cells. Photodynamic therapy using riboflavin and blue light should be explored further as it may perhaps be possible to exploit in treatment of skin diseases associated with keratinocyte hyperproliferation.

Dual-wavelength photo-killing of methicillin-resistant Staphylococcus aureus

“…In contrast, however, findings from another study demonstrated that at a wavelength of 470 nm, a significant loss of viability may be achieved in S. aureus (13). Furthermore, a recent study found that combining riboflavin with 450-nm light potentiated the killing of MRSA (14). Riboflavin has been shown to possess photosensitizing properties when activated with UV to eliminate microorganisms (15,16).…”

Effect of Different Wavelengths of Laser Irradiation on the Skin Cells

“…et al [ 43 ] obtained similar results and concluded that 460 nm blue light wavelength eradicates the C. albicans biofilm in vitro. Additionally, while examining the effects of blue light (450 nm, 84 J/cm 2 ) on methicillin-resistant Staphylococcus aureus, Makdoumi et al [ 44 ] discovered that blue light was able to eliminate 70% of bacteria, without affecting immortalized human keratinocytes. Despite these promising results suggesting that antifungal properties of blue laser Mamalis et al [ 45 ] showed that blue light-emitting diodes boosted, in a dose-dependent manner, the reactive oxygen species production, and inhibited proliferation and decreased migration speed of human fibroblasts.…”

Antimicrobial Photoinactivation Approach Based on Natural Agents for Control of Bacteria Biofilms in Spacecraft

“…However, Kashiwabuchi et al (2012) failed to show any killing of S. aureus after RF-based API in the same treatment conditions [ 140 ]. A study by Makdoumi et al (2010) resulted in the significant inactivation of various antibiotic-resistant bacteria ( Staphylococcus epidermidis , S. aureus , P. aeruginosa , E. faecalis ) mediated by RF photoactivated using UVA (365 nm) [ 141 , 142 , 143 ] and blue light (412 nm and 450 nm) [ 144 , 145 ] in thin layers of fluid (0.4–1.76 mm).…”

“…Furthermore, the required illumination doses have to be discussed and compared with general illumination conditions. RF can be excited by blue light and requires from 3 to 400 J/cm 2 according to the data available in the literature (see Table S1 of Supplementary Material ) [ 93 , 94 , 95 , 96 , 100 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 117 , 118 , 119 , 120 , 138 , 139 , 140 , 141 , 142 , 143 , 144 , 145 , 146 , 148 , 149 , 150 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 165 , 173 , 175 , 176 , 177 , 178 , 179 , 180 , 181 ,…”