Resin salve prepared from Norway spruce (Picea abies) has been used for centuries in traditional medicine to treat skin diseases. The authors studied with transmission and scanning electron microscopy, and with electron physiology, changes in cell wall and cell membrane of Staphylococcus aureus after exposure of the bacterial cultures to resin. After exposure, cell wall thickening, cell aggregation, changed branching of fatty acids, and dissipation of membrane potential of the bacterial cells were observed. The authors conclude that spruce resin affects the cell viability via changes in the cell wall and membrane, and impairs, thereby, the synthesis of energy in the bacteria.

Rosins (resins) are natural products of the coniferous trees. Purified rosin from the trunk of Norway spruce (Picea abies) is antibacterial against the gram-positive bacteria, but not against the gram-negative bacteria in agar plate diffusion test. In this study, we examined the antimicrobial properties of the coniferous rosin against bacteria and yeasts using the European Pharmacopoeia (EP) challenge test. The microbes tested were Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Candida albicans. To prepare challenge media, purified rosin was mixed with a biologically inert salve in varying concentrations. The microbes were inoculated (5 × 10(5) microbes (bacteria) or 5 × 10(4) microbes (yeast, C.albicans)) into 10 g of the rosin-containing challenge medium for 14 days at maximum. Samples were taken from the media for re-cultivation of the microbes at time intervals of 1 h, 24 h, 4, 7, and 14 days. The microbicidal efficacy of the challenge media was estimated by reduction of the number of the colony forming units (CFU) of microbes in the test samples. A reduction of more than 10(3) CFU for bacteria and 10(2) CFU for fungi in 7 days was considered to indicate a significant microbicidal action. Pure rosin was antimicrobial within 24 h against all microbes tested. The 0.5% rosin-salve medium (w/w) did not differ in microbicidal effects from the rosin-free salve medium (control). A raise of the rosin concentration resulted in increase of the microbicidal effect of the rosin-salve medium against all micro-organisms tested. Rosin concentration of 10% (w/w) in the medium significantly reduced the colonization of S. aureus (including MRSA) within 24 h and significantly reduced the colonization of all other micro-organisms within 4 days. Rosin is strongly microbicidal against a wide range of microbes, against both gram-positive and gram-negative bacteria, and against C. albicans, in the EP challenge test. The minimum concentration of rosin is 10% (w/w) to prevent the preservation of the microbes in the rosin-salve media.

Resin salve made from Norway spruce (Picea abies) is traditionally used in folk medicine to heal skin ulcers and infected wounds. Its antimicrobial properties were studied against certain human bacteria important in infected skin wounds. The sensitivity of the resin against Gram-positive and Gram-negative bacteria was studied in vitro by methods that are routinely used in microbiology laboratories. 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 study demonstrated antimicrobial activity of the resin salve and provided objective evidence of its antimicrobial properties. It gives some explanations why the traditional use of home-made resin salve from Norway spruce is experienced as being effective in the treatment of infected skin ulcers.

Resin is a natural product of coniferous trees. Salves manufactured from spruce resin (Picea abies) have been used for centuries to treat wounds and skin infections. We report a pilot clinical trial designed to investigate healing rates, factors that contribute to delayed wound healing, cost-effectiveness, and incidence of allergic reactions when resin salve is used to treat complicated surgical wounds. The trial involved 23 patients in whom wound healing after surgery was delayed. These patients were assigned to resin salve treatment. The primary outcome measure was the number of days to complete wound healing. Secondary objectives included an assessment of factors contributing to delayed wound healing, an estimation of associated costs, and an investigation into the occurrence of allergic reactions related to resin salve therapy. The study achieved a healing rate of 100%. The mean ± SD healing time was 43 ± 24 days. The mean ± SD wound size (length × width × depth) was (29 ± 19) × (12 ± 7) × (4 ± 3) mm. Wound size, use of corticosteroids or other immunosuppressants, and immobilization were statistically significant (P < 0.05) contributors to delayed wound healing and impaired re-epithelialization. The total mean ± SD costs of the resin salve treatment were €45.0 ± 26.0 per patient during the entire treatment period and €1.2 ± 0.5 per treatment day. The rate of allergic reactions was 0%. The results of this pilot trial indicate that complicated surgical wounds may be treated successfully with resin salve. The treatment method is clinically effective and cost-effective, and the rate of allergic reactions is low.

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