Phototherapy with psoralen plus ultraviolet-A (PUVA) as an Effective Intervention for Preventing Biofilm Formation in Staphylococcus aureus isolated from Patients' Wounds

BACKGROUND AND OBJECTIVESStaphylococcus aureus is a major pathogen associated with wound infections, and the formation ofbiofilms by this bacterium poses significant challenges to successful treatment. Biofilms not onlyprotect bacteria from antibiotics but also contribute to chronicity and recurrence of infections.Therefore, novel strategies are urgently required to prevent biofilm formation. This study aimed toinvestigate the potential of phototherapy with psoralen-ultraviolet A (PUVA) as a new treatmentmethod for preventing biofilm formation in S. aureus samples isolated from patients' wounds.MATERIALS AND METHODSSpecimens were collected from patients diagnosed with chronic infected wounds. The isolates werephenotypically confirmed using standard microbiological techniques. Biofilm-forming ability wasassessed using crystal violet staining and microtiter plate assays. PUVA treatment involved exposingthe bacterial isolates to a combination of ۸-methoxypsoralen (۸-MOP) and UVA irradiation at specificwavelengths and doses. Control groups consisting of untreated bacteria and bacteria treated witheither psoralen or UVA alone were included for comparison.RESULTS AND DISCUSSIONA total of ۳۰ S. aureus isolates were collected. PUVA treatment significantly inhibited biofilmformation and bacterial growth ability in ۲۸ out of ۳۰ isolates when the UVA dose was ۵۰۰ mj/cm۲and the ۸-MOP concentration was ۷۵ μg/ml or more. However, when the UVA dose increased to ۱۰۰۰mj/cm۲, in all ۳۰ isolates inhibition of biofilm formation started from the minimum concentration of۸-MOP (۵۰ μg/ml). The inhibition pattern continued with higher doses of UVA (۵۰۰۰ mj/cm۲), whilethe ۸-MOP concentration was at its minimum level. The effect of ۸-MOP alone or UVA alone at anydoses was similar to no-PUVA group.CONCLUSIONIt seems that PUVA treatment significantly reduce biofilm formation in a dose-dependent manner inS. aureus. As we were seeking for the lowest doses of both ۸-MOP and UVA, the optimal conditionsfor inhibiting biofilm formation seems to be ۷۵ μg/ml of ۸-MOP and ۵۰۰ mj/cm۲ UVA. Furtherresearch is needed to explore the mechanisms underlying the inhibitory effects of PUVA treatmentand to evaluate its potential clinical applications in preventing biofilm formation and improving themanagement of S. aureus infections.

کلیدواژه ها:

PUVA ، biofilm ، Staphylococcus aureus ، wound infection ، psoralen