Novel research which included usage of spruce resin salve on patients in 11 different medical health centres in Finland confirmed its significant role in faster recovery of skin wounds and pressure ulcers ^[4-5]. Approximately 40 patients were randomly chosen for therapy with traditionally prepared spruce resin salve (resin group) or  cellulose polymer gauzes (sodium carboxymethylcellulose hydrocolloid polymer) (control group). Pressure ulcers are areas of skin with superficial or deep tissue damage caused by pressure, shear, friction or a combination of these. It is more common with the people with limited mobility (diseases or old age). Pressure ulcers are difficult to treat, and there is, as yet, no ‘gold standard’ for their treatment. The inclusion criterion for research was grade II–IV pressure ulcer. Exclusion criteria were a life expectancy of less than 6 months or a malignant disease. The primary outcome measure was complete healing of the ulcer within 6 months. Secondary outcome measures were partial healing of the ulcer, and successful eradication of bacterial strains cultured from the ulcers at study entry. All ulcers healed in 94% in the resin group and in 44% patients in the control group. During the 6-month therapy period, only 6% of all ulcers was not healed in the resin group, although there was much improvement. Correspondingly, in the control treatment group 44% of all ulcers were  healed and 9% of ulcers in the control group became even worse during the follow-up.

Comparison of pressure ulcer healing between resin salve group patients and cellulose polymer gauzes group patients.

Traditional resin salve is significantly more effective in the treatment of infected and non-infected severe pressure ulcers than cellulose polymer gauzes.

Spruce resin antimicrobial (and antifungal) properties were studied against certain human bacteria important in infected skin wounds ^[6-7]. Resin excretion obviously provides trees with protection against bacterial and fungal infections. The resin salve exhibited a bacteriostatic effect against all tested Gram-positive bacteria but only against Proteus vulgaris of the Gram-negative bacteria. Interestingly, the resin inhibited the growth of bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE), both on agar plates and in culture media. The resin itself did not show any growth of bacteria or fungi when tested in various growth media (blood agar, chocolate agar, Sabouraud-dextrose agar, FAB medium). Nor was there any microbial growth when resin had been stored in the refrigerator or at room temperature for more than 2 years.

SEM image of MRSA.

The study directly confirmed antimicrobial activity of the resin salve and provided objective evidence of its antimicrobial properties. The scientists also believe that spruce resin take an active part in skin regeneration with its compounds. It gives some explanations why the traditional use of resin salve is experienced as being effective in the treatment of infected skin ulcers and healing of other similar skin injuries.