Zinc tape treatment of burns infected by Pseudomonas aeruginosa: an experimental study on guinea pigs

The effect of zinc on bacterial phagocytosis, killing and cytoprotection in human polymorphonuclear leucocytes

An in vitro study examining the effects of zinc treatment on human PMN cell phagocytosis and killing of Staphylococcus aureus and Staphylococcus epidermidis and the cytoprotection of zinc against staphylococcal toxins. Phagocytosis was studied by transmission electron microscopy using different microbiological techniques, one of which was designed to follow the kinetics of bacterial killing. No effect was found on phagocytosis and bacterial killing. The cytotoxic effects of a crude toxin and an alpha-toxin extracted from Staphylococcus aureus preparations were studied on human PMN cells using the standard 51Cr release assay. Both toxins induced a dose-dependent leakage of 51Cr, indicating cell membrane damage. These results were confirmed by electron microscopy during the phagocytosis of S. aureus, where severe PMN cellular degeneration was observed. The addition of zinc to PMN cells strongly inhibited the release of 51Cr. In conclusion, our results show that zinc in higher than physiological concentrations does not inhibit PMN cell functions such as phagocytosis and intracellular killing of S. aureus and S. epidermidis. The addition of zinc may be beneficial in certain clinical situations, such as wound healing, zinc deficiency and infections involving toxin-producing bacteria, e.g. S. aureus.

Zinc as a growth factor for Aspergillus sp. and the antifungal effects of root canal sealants

Noninvasive aspergillosis of the maxillary sinus is frequently associated with extrusion of root canal cements into the sinus, and it has been suggested that zinc oxide-based materials might promote infection because zinc is a growth factor for Aspergillus sp. To investigate this possibility pure zinc oxide-eugenol cement and five other cements were tested for antifungal activity against five strains of Aspergillus fumigatus, one strain of A. niger, and one strain of A. flavus by zone inhibition and by spectrophotometric measurement of growth rates at various zinc concentrations. All cements had antifungal activity. Eugenol-containing materials had the most activity, but this activity was reduced with mixing and setting. No growth enhancement attributable to zinc was detected by either method. To determine whether contaminated materials might introduce spores into the sinus, 63 samples taken from one clinic were cultured. Aspergillus sp. was isolated from two.

The effect of zinc in the form of erythromycin-zinc complex (Zineryt lotion) and zinc acetate on metallothionein expression and distribution in hamster skin

The occurrence of zinc-induced synthesis of metallothionein in skin after topical application of the anti-acne drug Zineryt lotion was investigated in hamster ears. The dinitrophenyl hapten-sandwich immunohistochemical method involving a monoclonal anti-metallothionein (MT) antibody (E9) was used to detect and localize zinc-binding MT in the 'treated' and untreated hamster skin. Atomic absorption spectrophotometry and dithizone histochemistry indicated that zinc penetrated the skin more readily, and accumulated more efficiently within the sebaceous glands, when applied to the skin surface as the organo-zinc complex, rather than as the inorganic zinc salt. MT and zinc had similar distributions in hamster skin exposed to the metal. Thus, MT immunoreactivity was especially intense in the sebaceous glands of Zineryt lotion-treated skin, with evidence of nuclear distribution in some cells. Zinc delivered to the sebaceous glands, and released from the organo-complex under the prevailing aqueous conditions, certainly induced MT synthesis; the cysteine-rich protein may protect the pilosebaceous units during the inflammatory phase of acne by scavenging generated oxyradical species.

Effects on wound healing of zinc oxide in a hydrocolloid dressing

BACKGROUND

Zinc oxide incorporated in gauze enhances healing of chronic wounds in humans and experimental pig wounds.

OBJECTIVE

The purpose of this study was to examine the effects of zinc oxide added to a hydrocolloid dressing on the healing of surgical wounds in domestic pigs.

METHODS

Forty partial-thickness wounds (2.2 x 2.2 cm and 400 microns deep) were treated with different zinc oxide concentrations, and epithelialization was evaluated morphometrically in a total of 320 histologic sections. Wound closure, bacterial growth, and inflammation were studied in eight full-thickness wounds (2.5 x 4.5 cm). The level of serum zinc was determined before and after treatment.

RESULTS

In partial-thickness wounds, concentrations of zinc oxide at or below 1.0% (wt/wt) inhibited epithelialization, whereas no effect was observed at zinc oxide concentrations from 2% to 6%. In full-thickness wounds, zinc oxide (6%) reduced bacterial growth by about 2 log units and increased the inflammatory response in the granulation tissue, but had no effect on healing when compared with control (hydrocolloid alone). Serum zinc levels remained unchanged throughout the treatment period.

CONCLUSION

Apart from inhibiting bacterial growth, no additional beneficial effects on wound healing in nutritionally balanced pigs were found by supplementing a hydrocolloid dressing with zinc oxide.

Antibacterial effects of zinc oxide, rosin, and resin acids with special reference to their interactions

The growth inhibiting capacity of zinc oxide combined with ordinary rosin (Portuguese rosin), abietic acid or dehydroabietic acid was studied using two different methods. To mimic the actual treatment of wounds, circular tapes or sensitivity discs were placed on Müller-Hinton-agar plates that had been seeded with various facultative aerobic bacteria, and the zones of inhibition were measured. The agar dilution method was used to measure the minimum inhibitory concentration (MIC). Inhibition of growth was restricted to Gram-positive facultative aerobic bacteria for the individual substances zinc oxide, Portuguese rosin, or resin acids, as well as for combinations of these. In general the combination of zinc oxide and dehydroabietic acid was a more potent antibacterial substance than the corresponding combination of zinc with rosin or abietic acid. These combinations commonly had synergistic antibacterial effects.

Antibacterial effect of zinc oxide in vitro

Antibacterial activity, zinc concentrations and pH were measured in Müller-Hinton broth containing different amounts of zinc oxide and inoculated with Staphylococcus aureus (10(6) colony forming units/ml). The minimum inhibitory concentrations (MIC) of zinc oxide to different clinical isolates were determined using the Müller-Hinton agar dilution tests. Gram-positive bacteria were most susceptible. Gram-negative aerobic bacteria and streptococci were usually not inhibited even at the highest concentrations used (1024 micrograms/ml), but staphylococci--particularly some isolates of Staphylococcus epidermidis--were sensitive enough to allow determination of their MIC.

The effect of zinc oxide on Staphylococcus aureus and polymorphonuclear cells in a tissue cage model

The effect of zinc oxide on S. aureus (209 P) was studied in steel net tissue cages implanted subcutaneously in guinea pigs and rabbits. Zinc oxide installed in the tissue cages created high, sustained concentrations of zinc in the cage fluid throughout the study. In a concentration of 22 mmol/l zinc oxide reduced viable counts in tissue cage fluid inoculated with S. aureus. No deleterious effect was observed on polymorphonuclear cell function.

Antibacterial activity of rosin and resin acids in vitro

The antibacterial effects of rosins and resin acids were studied in vitro using three methods, disc diffusion on agar, agar dilution, and broth dilution. Rosin and some resin acids had antibacterial effects that were restricted to Gram-positive bacteria. The abietic type of acids had a more pronounced antibacterial activity than the pimaric and labdane acids when the disc diffusion method was used but there was no inhibition of growth of Gram-negative bacteria. Among the individual resin acids, dehydroabietic acid was generally the most potent, when disc diffusion on agar was used, and prediffusion increased the inhibitory effect. The composition of the pure resin acids dehydroabietic, neoabietic, and isopimaric acid did not change during the experiment, but abietic and levopimaric acid were converted into dehydroabietic acid by the addition of Müller-Hinton agar. In conclusion the old tradition of treating wounds with pitch, sap, rosin, or rosin containing tapes might therefore have some antibacterial relevance.

The effects of an occlusive zinc medicated dressing on the bacterial flora in excised wounds in the rat

The effects of three different dressings - two occlusive and one non-occlusive - on the bacterial flora of excised wounds in rats were studied. The number of colony forming units per gram of granulation tissue were significantly lower 4, 8 and 12 days postoperatively in wounds treated with a zinc medicated occlusive dressing compared with wounds treated with non-zinc medicated occlusive hydrocolloid dressing or wet-to-dry non-occlusive gauze dressing. The minimum inhibitory concentration (MIC) of zinc sulphate was determined on different strains of bacteria isolated from the wounds of rats and on strains isolated from humans. The most susceptible species isolated from both rat wounds and humans were Streptococcus sp., STaphylococcus aureus and Escherichia coli; whereas, Proteus and Enterococcus sp. had higher MIC-values. In vitro, the hydrocolloid dressing disclosed no antibacterial effects. If the practitioner prefers an occlusive dressing we believe, due to our animal and in vitro experiments, that the zinc medicated occlusive dressing will reduce the risk of wound infection in man.

The effects of occlusive dressings on inflammation and granulation tissue formation in excised wounds in rats

The effects on the healing of full-thickness excisional wounds treated with either of two occlusive dressings (Mezinc or Duoderm) were compared with the effects of gauze soaked in saline. The wounds were made on 86 rats and were examined clinically, histologically and biochemically four, eight and twelve days after wounding. Four days postoperatively the Duoderm-treated wounds differed significantly from the other two groups. Clinically, an adherent discolored gelatinous mass remained after removal of the firm part of the Duoderm dressing. Histologically it corresponded to a superficial exudate containing polymorphonuclear leukocytes (PMNs), macrophages and condensed foreign material. There was also a more extensive inflammatory reaction in the underlying tissues compared with gauze or Mezinc treatment and debris was seen in vesicles extracellularly and in foamy macrophages. Foamy macrophages were only seen in the Duoderm-treated wounds. These macrophages were mainly confined to the granulation tissue, which was about twice as thick as in the other two treatment groups twelve days after excision.

Effects of zinc oxide in an occlusive, adhesive dressing on granulation tissue formation

The role of zinc in an occlusive, adhesive dressing (Zn-tape) was investigated in two experiments in the rat. In the first one Zn-tape was compared with a similar tape without zinc components and also with an inert plastic coated fabric with regard to the wound inflammatory reaction in excisional wounds. In the second experiment we attempted to assess possible systemic effects of zinc absorbed from Zn-tape-treated excisional wounds by studying the granulation tissue formation in subcutaneously implanted Ivalon sponges. The excisional wounds were treated with either the Zn-tape or a titanium tape in which the zinc oxide was replaced by an equivalent amount of titanium dioxide (Ti-tape). The granulation tissue produced was evaluated histologically, histochemically and biochemically. The plain adhesive mass and the Ti-tape elicited an intense inflammatory reaction as indicated both by high activities of alkaline phosphatases and histological examination. The Zn-tape reduced inflammatory processes in the granulation tissue of the excisional wounds. Zinc levels in serum and liver were raised in Zn-tape-treated animals. We conclude that zinc oxide in the Zn-tape affects inflammatory reactions in the granulation tissue of the wounds, possibly through a continuous release of zinc ions and by modifying the adhesive components of the Zn-tape. There was no evidence of a systemic effect of zinc absorbed from the excisional wounds on the granulation tissue formation in the implanted Ivalon sponges.

Topical zinc oxide treatment improves arterial and venous leg ulcers

We performed a randomized, double-blind study of the efficacy of locally applied zinc oxide on the healing of leg ulcers. Thirty-seven geriatric patients, nineteen with arterial and eighteen with venous leg ulcers, were treated either with a gauze compress medicated with zinc oxide (400 micrograms ZnO/cm2) or with an identical compress without zinc oxide. The treatment was assessed from ulcer size measurements and the presence or absence of granulation and ulcer debridement over a period of 8 weeks. The zinc-treated patients (83% success rate) responded significantly better (P less than 0.05) than the placebo-treated patients (42% success rate). The results suggest that healing of leg ulcers is improved after the addition of zinc oxide to the local regimen.

Treatment of fingertip amputations with bone exposure. A comparative study between surgical and conservative treatment methods

The long-term results following 36 surgically and 34 conservatively treated fingertip amputations with bone exposure are presented in a retrospective study. Surgery did not produce better results even though it was performed by skilled hand surgeons. The advantages of the conservative (mainly adhesive zinc tape) treatment method are pointed out. The regenerative capacity of the amputated fingertip is shown and discussed.

Wound contraction and zinc absorption during treatment with zinc tape

Wound healing, wound contraction and zinc absorption were studied in rats operated on with excisional wounds on each side of the dorsolateral aspects of the backs. The wounds were covered with plastic foil, plastic tape or zinc tape. The shortest healing time was seen in wounds treated with plastic foil when the contralateral wound was treated with zinc tape. Final wound contraction was decreased when the wound was treated with plastic-coated tape and zinc tape that was fixed to the surrounding skin. An increase in serum zinc concentration was seen 7 days postoperatively when the animals were treated with zinc tape and a decrease in serum zinc concentration was seen at the same time when only plastic foil was used.