HealthDay News — Riboflavin-ultraviolet A (UVA) collagen crosslinking (CXL) used in photoactivated chromophore for infectious keratitis (PACK) has bactericidal efficacy for both antibiotic resistant and non-resistant bacteria, according to a study published online in Clinical & Experimental Ophthalmology.
Karim Makdoumi, MD, PhD, and Anders Bäckman, PhD, from Örebro University in Sweden, examined bacterial strains (Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis) from clinical isolates, with and without antibiotic resistance. Bacteria were dispersed in phosphate buffered saline and diluted; riboflavin was added and the solution was spread on a microscope slide. UVA exposure was followed on eight separate exposures that were made for each strain; the degree of elimination of pathogens was assessed.
The researchers found that the bactericidal efficacy of exposure varied between the tested microorganisms, with mean elimination ranging from 60 to 92%. Both the evaluated Pseudomonas strains had the most extensive bactericidal efficacy, while the Enterococcus faecalis strains had the least extensive efficacy. Antibiotic-resistant and non-resistant strains had similar reductions, apart from Staphylococcus aureus, which had a greater extent of eradication in the resistant strain versus the non-resistant strain (P = 0.030).
“UVA-riboflavin settings used in PACK-CXL is effective in reducing both antibiotic-resistant and non-resistant bacteria,” the authors write. “Antibiotic resistance does not appear to be protective against the photo-oxidative exposure.”
1. Makdoumi K, Backman A. Photodynamic UVA-riboflavin Bacterial Elimination in Antibiotic Resistant Bacteria. Clin Exp Opthalmology. 2016; doi: 10.1111/ceo.12723.