A biofilm is a collection of microbial cells that are attached to a surface and embedded in a self-produced extrapolymeric substance. The understanding of the biofilm phenotype is important in the understanding of bacteria in vitro but it has been difficult to translate biofilm science to the clinical setting. More recently, preliminary criteria for defining biofilm associated diseases have been proposed and the purpose of this study was to create a biofilm-associated wound model based on these criteria. Using a porcine model, partial thickness wounds were inoculated with a wound isolate Staphylococcus aureus strain. Wounds were then treated with either one of two topical antimicrobial agents (mupriocin cream or triple antibiotic ointment) within 15 minutes to represent planktonic bacteria or 48 hours after initial inoculation to represent biofilm-associated wound infection. Using light microscopy, scanning electron microscopy and epifluorescence microscopy, we were able to observe biofilm-like structures in wounds after 48 hours of inoculation and occlusion. The in vivo antimicrobial assay was used to demonstrate that both mupirocin cream and the triple antibiotic ointment were effective in reducing planktonic S. aureus but had reduced efficacy against biofilm-embedded S. aureus. Our results demonstrated that S. aureus form firmly attached microcolonies and colonies of bacteria encased in an extracellular matrix on the surface of the wounds. These biofilm-like communities also demonstrated increased antimicrobial resistance when compared with their planktonic phenotype in vivo. The structural and physiological results support the hypothesis that bacterial biofilms play a role in wound colonization and infection.
We describe what we believe to be the seventh report of a combined tumor with histologic features of both malignant melanoma and a squamous cell carcinoma, a squamomelanocytic tumor. An 82-year-old woman presented with a nondescript, skin-colored, firm papule on her nose. Histology showed 2 different neoplastic cell proliferations: atypical squamoid cells and irregularly shaped nests of atypical pigmented epithelioid cells (melanocytes) arranged in small to large nests at the dermal-epidermal junction and within the epidermis. Both components were closely admixed and restricted to the epidermis. Immunohistochemistry showed diffuse cytoplasmic reactivity for pancytokeratin in all areas supporting the histopathologic features of a squamous cell carcinoma. S-100 and melanoma antigen recognized by T cells 1 did not stain these areas and showed strong selective positivity for the atypical melanocytic component. A true malignant proliferation of 2 distinct cell phenotypes due to close paracrine interactions is our favored interpretation because of the intimate admixture, distinct immunohistochemical pattern, and unique histologic features. Perhaps, chronic sun damage (facial location and advanced age) and reduced immunity (history of other malignancies, particularly recent history of a basal cell carcinoma) played a complementary role for the development of the squamomelanocytic tumor.
Skin cancer is the most common form of cancer in the United States, with the incidence increasing considerably. At current rates in the United States, a skin cancer will develop in 1 in 6 people during their lifetime.1 The most common of skin cancers may be categorized into 2 major groups: melanoma and nonmelanoma skin cancers. The latter group consists primarily of basal cell carcinomas and squamous cell carcinomas. Roughly 1,200,000 nonmelanoma skin cancers develop annually in the United States. These tumors are rarely fatal, but are considered to be fast growing tumors that if neglected may be locally and functionally destructive.In contrast, melanoma represents 5% of all diagnosed cancers in the United States, 15% of which prove to be fatal.3 Although melanoma is seen more with increasing age, it is the most frequent cancer plaguing women aged 25 to 29 years, and the second most frequent cancer afflicting women aged 30 to 34.2 Tumor depth is the most important prognostic indicator for melanoma, thus early recognition and management are imperative for improved therapeutic outcome.Although the nonmelanoma and melanoma skin cancers encompass the vast majority of skin cancers, there is a large number of other malignancies of the skin that are less commonly confronted by the clinician. Neoplasms of the skin classically have been divided into those that differentiate from the epidermis, dermis, adnexal structures of the skin, and those derived systemically. This review focuses on the most frequent malignant neoplasms, and divides them into those that are classically designated nonmelanoma skin cancers (also known as keratinocytic tumors), melanoma, and other less common skin cancers of the skin. An extensive list of skin malignancies is provided in Box 1.
We demonstrated biofilm formation in vitro using a wound model. This model may provide a basis on which future studies may explore therapeutic modalities to prevent and eradicate pathogenic bacterial biofilm. The authors have indicated no significant interest with commercial supporters.
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