A tiny study looked at whether shining low‑level laser light on pressure sores changes the body’s natural antimicrobial peptide LL‑37 and helps heal the wound, especially when bacteria are present. They saw LL‑37 levels rise after two weeks of laser treatment, but they couldn't clearly show that the sores healed better, and the sample size was very small.

Low-level laser therapy is used in managing chronic wounds including pressure ulcers. Less is known about its impact on the healing process if an inhibitive agent e.g. bacterial infection takes place. Modulating non-specific immunity processes might eliminate bacteria if laser therapy is applied. To investigate the impact of low-level laser therapy on pressure ulcer dynamics considering an infectious agent and cathelicidin LL-37 concentration. The study comprised 6 patients with pressure ulcers ranging from stage II to III in Torrance classification and 12 patients without pressure ulcers. Venous blood sample and decubitus wound swab were taken - in study groups A at baseline and after 2 weeks; in control group B once - at a specific point of time. The swabs served for species identification. Drug susceptibility of isolated pathogens and cathelicidin LL-37 in serum concentration were measured. In study group A, the following bacteria predominantly occurred: <i>S. aureus</i>, <i>E. faecalis, P. mirabilis, P. aeruginosa,</i> while in control group B, excluding one MRSA case, <i>S. hominis, S. epidermidis, D. nishinomiyaensis, A. haemolyticus</i> (physiological flora) were present. HLGR resistance mechanisms were detected when analyzing drug susceptibility panels. Study group A findings demonstrated a statistically significant difference between the levels of cathelicidin LL-37 concentration at baseline and at the end. There is insufficient information to accurately determine the effect of LLLT on pressure ulcer dynamics considering an infectious agent. These effects may occur if innate immunity processes are modulated so that laser therapy might eliminate bacteria indirectly.