Eradication ofPropionibacterium acnesby its endogenic porphyrins after illumination with high intensity blue light

Abstract

Propionibacterium acnes is a Gram-positive, microaerophilic bacterium that causes skin wounds. It is known to naturally produce high amounts of intracellular porphyrins. The results of the present study confirm that the investigated strain of P. acnes is capable of producing endogenic porphyrins with no need for any trigger molecules. Extracts from growing cultures have demonstrated emission peaks around 612 nm when excited at 405 nm, which are characteristic for porphyrins. Endogenic porphyrins were determined and quantified after their extraction from the bacterial cells by fluorescence intensity and by elution retention time on high-performance liquid chromatography (HPLC). The porphyrins produced by P. acnes are mostly coproporphyrin, as shown by the HPLC elution patterns. Addition of delta-aminolevulinic acid (ALA) enhanced intracellular porphyrin synthesis and higher amounts of coproporphyrin have been found. Eradication of P. acnes by its endogenic porphyrins was examined after illumination with intense blue light at 407-420 nm. The viability of 24 h cultures grown anaerobically in liquid medium was reduced by less than two orders of magnitude when illuminated once with a light dose of 75 J cm(-2). Better photodynamic effects were obtained when cultures were illuminated twice or three times consecutively with a light dose of 75 J cm(-2) and an interval of 24 h between illuminations. The viability of the culture under these conditions decreased by four orders of magnitude after two illuminations and by five orders of magnitude after three illuminations. When ALA-triggered cultures were illuminated with intense blue light at a light dose of 75 J cm(-2) the viability of the treated cultures decreased by seven orders of magnitude. This decrease in viability can occur even after a single exposure of illumination for the indicated light intensity. X-ray microanalysis and transmission electron microscopy revealed structural damages to membranes in the illuminated P. acnes. Illumination of the endogenous coproporphyrin with blue light (407-420 nm) apparently plays a major role in P. acnes photoinactivation. A treatment protocol with a series of several illuminations or illumination after application of ALA may be suitable for curing acne. Treatment by both pathways may overcome the resistance of P. acnes to antibiotic treatment.

Inhibitory effects of 405 nm irradiation on Chlamydia trachomatis growth and characterization of the ensuing inflammatory response in HeLa cells

“…Endogenously produced porphyrins, like coproporphyrin, uroporphyrins, and protoporphyrin IX, have been shown to be produced by both Gram positive and negative bacteria [25,39] though, to our knowledge, porphyrin production by C. trachomatis has not yet been demonstrated. Considering the intracellular nature of C. trachomatis, a second photo inactivation mechanism might be associated with altered expression of eukaryotic proteins in response to 405 nm irradiation.…”

Heat‐killed Propionibacterium acnes is capable of inducing inflammatory responses in skin

“…In addition, other antibiotics have also been shown to possess anti‐inflammatory/immunomodulatory properties such as decreasing the release of proinflammatory cytokines (TNF‐α, IL‐1, IL‐6) and increasing the secretion of anti‐inflammatory cytokines (IL‐10) (6). Similarly blue light (405–420 nm) which is bactericidal for P. acnes (27) has been shown to be effective in the treatment of mild to moderate inflammatory acne lesions (28) and also has direct anti‐inflammatory activity independent of the bactericidal effects (29). Thus the anti‐acne benefits from many therapeutic agents may be due to the direct anti‐inflammatory activity in addition to or independent of the anti‐microbial activity.…”

Prospects for a novel ultrashort pulsed laser technology for pathogen inactivation

“…It has been known that photo-stimulation of endogenous intracellular porphyrin molecules in the bacteria by continuous wave visible light irradiation may result in the production of reactive oxygen species (ROS), predominantly singlet oxygen, and consequently, damage to the DNA and the death of bacteria [30-35]. Therefore, the other mechanism which can contribute to the inactivation of Salmonella typhimurium by a visible USP laser is the photo-production of ROS.…”