%0 Journal Article
%T Hypocrellin B-Mediated Photodynamic Inactivation of Gram-Positive Antibiotic-Resistant Bacteria: An In Vitro Study.
%A Otieno W
%A Liu C
%A Deng H
%A Li J
%A Zeng X
%A Ji Y
%J Photobiomodul Photomed Laser Surg
%V 38
%N 1
%D Jan 2020
%M 31634029
%F 2.744
%R 10.1089/photob.2019.4656
%X Background: The search for alternative therapeutics against antibiotic-resistant bacteria is highly desirable. A promising approach is photodynamic antimicrobial chemotherapy. Objective: This work evaluated the photodynamic inactivation (PDI) efficacy of hypocrellin B (HB) on Gram-positive antibiotic-resistant bacteria. Methods: PDI efficacy of HB on Gram-positive standard and antibiotic-resistant Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pneumonia and Gram-negative Escherichia coli and Klebsiella pneumoniae was assessed. HB photoactivity on biofilms formed by the Gram-positive bacteria and its cytotoxicity on mammalian CT26 cells were also investigated. Results: HB showed no obvious dark toxicity, but provided concentration-dependent inactivation of bacteria and mammalian cells. After irradiation with 72 J/cm2 light, 100 μM of HB achieved about 7 log10 reductions in bacterial survival of Gram-positive strains, but yielded only 2 log10 reductions in bacterial survival of Gram-negative strains. Gram-positive bacteria were as susceptible to PDI in biofilms as in planktonic suspensions, but the efficacy was attenuated. Conclusions: The results suggested that HB could serve as a potential antibacterial photosensitizer against Gram-positive antibiotic-resistant bacteria.