Abstract
The auricle is a frequently injured part of the head and neck during thermal injury leading to ear deformity. The burned ear represents one of the most difficult problems for reconstructive surgeons. Mafenide acetate is a topical agent used routinely for these patients, but it has some disadvantages including painful application and allergic rash. Some authors have reported the healing effect and antibacterial activity of honey. The study reported here was undertaken to compare the effect of honey and mafenide acetate on auricular burn in rabbit. In our study, although the pathologic score of the honey group was better than that of the mafenide group both on 14 and 21 days after burning, it was not statistically significant. In the mafenide acetate group, deep complication of burn (chondritis) was significantly lower than that of the honey group. In conclusion, in contrast to healing and antibiotic activity reported for honey, it may have failure in preventing deep bacterial complications of wound (like chondritis). So in deep wounds, the use of honey as dressing is not recommended.
1
Introduction
The auricle is a frequently injured part of the head and neck during thermal injury leading to ear deformity. The burned ear represents one of the most difficult problems for reconstructive surgeons because of the dense scarred tissue that usually surrounds it . From an anatomical point of view, the ear has no subcutaneous tissue to protect the cartilaginous framework. This cartilaginous framework, once exposed or injured, is particularly susceptible to infection .
Auricular deformities can be a result of both direct thermal injuries and subsequent chondritis, which is a severe complication of ear burns that can even destroy the unburned cartilage if not recognized early . Auricular chondritis secondary to bacterial invasion of the cartilage is prevented by the routine use of topical mafenide acetate on all burned ears .
Mafenide acetate is a topical agent with a broad spectrum of activity because of its sulfa moiety. It is particularly useful against resistant Pseudomonas and Enterococcus species. It can also penetrate eschar. Its disadvantages include painful application on the skin, for example, in second-degree wounds. It can also cause an allergic rash, and it has carbonic anhydrase inhibitory characteristics that can result in metabolic acidosis when applied over large surfaces. For these reasons, mafenide acetate is typically reserved for small full-thickness injuries .
Honey has been used for medicinal purposes since ancient times. It was used topically in ayurvedic medicine during 2500 bc , and Egyptians, Greeks, and Romans used it as well. Hippocrates prescribed honey for various indications including the management of wounds and gastritis. In addition, the wound-healing properties of honey were mentioned in the Qur’an and the Bible .
It has been proposed that the healing effect of honey could be due to various physical and chemical properties. The high osmolarity and acidity of honey are among the physical characteristics that contribute to its antibacterial activity. Hydrogen peroxide, volatiles, organic acids, flavonoids, beeswax, nectar, pollen, and propolis are important chemical factors that provide antibacterial properties to honey .
The antibacterial activity of honey has been confirmed in numerous studies . White et al has reported that the major antibacterial factor in honey is hydrogen peroxide, which is produced by glucose oxidase originating from hypopharyngeal glands of honey bees. In addition, there is catalase in honey, which originates from pollin. The level of hydrogen peroxide in a given honey is determined by relative levels of glucose oxidase and catalase .
Likewise, most phytochemical factors withstand dilution in wound fluids. Overall, honey has a restraining influence on the growth of most bacteria, including some methicillin-resistant Staphylococcus aureus strains. This makes honey attractive for the prevention and treatment of infections in chronic wounds , as well as for the treatment of acute wounds. Unlike most conventional local chemotherapeutics, honey does not lead to the development of antibiotic-resistant bacteria, and it may be used continuously . Rapid clearance of infections, rapid suppression of inflammation, minimization of scarring, and stimulation of angiogenesis as well as tissue granulation and epithelium growth were reported with using honey for dressing .
All these physical and chemical factors give honey unique properties as a wound dressing. This study was undertaken to compare the effect of honey and mafenide on auricular burn in rabbit.
2
Materials and methods
Experimental design and treatment of animals were approved by the Animal Care Committee of Shiraz University of medical sciences. Fifteen male white rabbits (3.4 ± 0.4 kg) were used for the evaluation of ear burn wounds. Ketamine (25 mg/kg) and xylazine (1 mg/kg) were injected intramuscularly into the rabbits to induce sedation before a heated iron stamp was applied on the back of the auricles. The heated stamp (in boiling water 95°C ± 2°C) was applied for 8 seconds to form a dermal burn wound (burn area, 3.8 cm 2 ). All left auricular wounds underwent daily application of topical mafenide, and all right auricular wounds were treated with daily topical honey after the wound had been irrigated with normal saline (unprocessed honey obtained from Dena Mountains).
The biopsy samples were taken on day 14 from 5 rabbits and day 21 from the remaining 10 rabbits, and the healing was evaluated macroscopically and histopathologically. Photographs were taken of the wound areas on days 7, 14, and 21.
The biopsies of the skin samples were fixed in a 10% formalin solution, then embedded in paraffin block and sectioned to 4- μ m increments. The sections were positioned on a slide and stained with hematoxylin-eosin.
A histologic scale adapted from Singer et al was used ( Table 1 ). Each item was graded by pathologist according to a semiquantitative approach as absent (0) and present (1) without the knowledge of the specimen groups.
| Score | |
|---|---|
| Hyperkeratosis | |
| Absent | 1 |
| Present | 0 |
| Epidermal hyperplasia | |
| Absent | 1 |
| Present | 0 |
| Hair follicles | |
| Absent | 1 |
| Present | 0 |
| Apocrine gland | |
| Absent | 1 |
| Present | 0 |
| Smooth muscle | |
| Present | 1 |
| Absent | 0 |
| Collagen orientation | |
| Normal | 3 |
| Abnormal collagen in the papillary dermis | 2 |
| Abnormal collagen in the upper reticular dermis only | 1 |
| Fibroplasia (increased no. of fiberocytes) | |
| Absent | 1 |
| Present | 0 |
| Vascular | |
| Absent | 1 |
| Present | 0 |
Histologic results were analyzed using the nonparametric Wilcoxon rank sum test. A P < .05 was considered as statistically significant.
2
Materials and methods
Experimental design and treatment of animals were approved by the Animal Care Committee of Shiraz University of medical sciences. Fifteen male white rabbits (3.4 ± 0.4 kg) were used for the evaluation of ear burn wounds. Ketamine (25 mg/kg) and xylazine (1 mg/kg) were injected intramuscularly into the rabbits to induce sedation before a heated iron stamp was applied on the back of the auricles. The heated stamp (in boiling water 95°C ± 2°C) was applied for 8 seconds to form a dermal burn wound (burn area, 3.8 cm 2 ). All left auricular wounds underwent daily application of topical mafenide, and all right auricular wounds were treated with daily topical honey after the wound had been irrigated with normal saline (unprocessed honey obtained from Dena Mountains).
The biopsy samples were taken on day 14 from 5 rabbits and day 21 from the remaining 10 rabbits, and the healing was evaluated macroscopically and histopathologically. Photographs were taken of the wound areas on days 7, 14, and 21.
The biopsies of the skin samples were fixed in a 10% formalin solution, then embedded in paraffin block and sectioned to 4- μ m increments. The sections were positioned on a slide and stained with hematoxylin-eosin.
A histologic scale adapted from Singer et al was used ( Table 1 ). Each item was graded by pathologist according to a semiquantitative approach as absent (0) and present (1) without the knowledge of the specimen groups.
