Mycoplasma Removal from Cell Culture Using Antimicrobial Photodynamic Therapy

Abstract

Objective: The objective of this research was to determine the effectiveness of antimicrobial photodynamic therapy (aPDT) in the removal of mycoplasmas from contaminated cells. Background data: Mycoplasmas often contaminate cell cultures. The cell-contaminating mycoplasmas are removed by antibiotics, but the use of antibiotics usually induces antibiotic-resistant bacteria. aPDT is expected to be a possible alternative to antibiotic treatments for suppressing infections. Materials and Methods: Mycoplasma salivarium (Ms)-infected human embryonic kidney (HEK) 293 cells were irradiated using a red light-emitting diode (LED) in the presence of methylene blue (MB) as a photosensitizer. The Ms viable count was determined using culture on agar plates or using a mycoplasma detection kit. Results: aPDT performed using red LED irradiation was effective in decreasing live Ms in the presence of MB without damaging the HEK293 cells. aPDT removed live Ms from the infected cells after washing the cells with sterilized phosphate-buffered saline (PBS) to decrease the initial number of live Ms before aPDT. Conclusions: This study suggests that aPDT could remove mycoplasmas from contaminated cells.

The role of the light source in antimicrobial photodynamic therapy

“…The highest concentration (319.84 g L −1 = 1 M) was tested on Herpes simplex viruses cultured in infected monolayers of cell lines, and the lowest on Mycoplasma salivarium in vitro . 332,353 We note that the highest concentrations reported seem unreasonable as the solubility of methylene blue in water is reported to be up to 0.13 M (43 g L −1 ) thus concentrations of MB greater than its water solubility were rejected from further analysis. 462 For antifungal and antibacterial PDT the methylene blue concentration range is very broad but accumulation of values is observed between 0.31–0.031 mM (0.1–0.01 g L −1 ) (Fig.…”