Near-infrared LEDS provide persistent and increasing protection against E. faecalis.

Area of Science:

• Microbiology
• Biotechnology
• Photomedicine

Background:

• Previous research indicated light-emitting diodes (LEDs) can reduce Enterococcus faecalis viability in vitro.
• Concurrent treatment with 1.0% sodium hypochlorite (NaOCl) and LED achieved total bacterial inactivation in prior studies.

Purpose of the Study:

• To determine if LED-induced photoinactivation of Enterococcus faecalis is a stable effect over one week.
• To assess if a lower concentration of NaOCl (0.5%) combined with LED irradiation can achieve total bacterial inactivation.

Main Methods:

• Bacterial suspensions were treated with 0.5% NaOCl, 880-nm LED irradiation, or a combination of both for 5 minutes.
• Colony-forming units per milliliter (CFU/mL) were analyzed at 5 minutes, 24 hours, 48 hours, and 1 week.
• Live/dead assays and fluorescent microscopy were employed for all treatment groups and time points.

Main Results:

• All three protocols significantly reduced bacterial counts compared to controls.
• NaOCl and NaOCl+LED treatments were most effective in the initial 48 hours.
• LED treatment alone showed a sustained decrease in bacterial count after one week, irrespective of NaOCl presence.
• 0.5% NaOCl with LED irradiation did not result in total bacterial inactivation.

Conclusions:

• LED irradiation alone provides a stable, long-term reduction in Enterococcus faecalis viability.
• While effective short-term, combining 0.5% NaOCl with LED does not guarantee complete bacterial inactivation.
• LED phototherapy presents a promising avenue for sustained antimicrobial effects against Enterococcus faecalis.