This article discusses photoaging or premature skin aging from chronic ultraviolet exposure. This is an important cosmetic concern for many dermatologic patients. Clinical signs include rhytids, lentigines, mottled hyperpigmentation, loss of translucency, and decreased elasticity. These changes are more severe in individuals with fair skin and are further influenced by individual ethnicity and genetics. Photoaging may be prevented and treated with a variety of modalities, including topical retinoids, cosmeceuticals, chemical peels, injectable neuromodulators, soft tissue fillers, and light sources.

Chronic wounds contain complex polymicrobial communities of sessile organisms that have been underappreciated because of limitations of standard culture techniques. The aim of this work is to combine recently developed next-generation investigative techniques to comprehensively describe the microbial characteristics of chronic wounds. Tissue samples were obtained from 15 patients with chronic wounds presenting to the Johns Hopkins Wound Center. Standard bacteriological cultures demonstrated an average of 3 common bacterial species in wound samples. By contrast, high-throughput pyrosequencing revealed increased bacterial diversity with an average of 17 genera in each wound. Data from microbial community profiling of chronic wounds was compared to published sequenced analyses of bacteria from normal skin. Increased proportions of anaerobes, Gram-negative rods and Gram-positive cocci were found in chronic wounds. In addition, chronic wounds had significantly lower populations of Propionibacterium compared to normal skin. Using epifluorescence microscopy, wound bacteria were visualized in highly organized thick confluent biofilms or as scattered individual bacterial cells. Fluorescent in-situ hybridization allowed for the visualization of Staphylococcus aureus cells in a wound sample. Quorum sensing molecules were measured by bioassay to evaluate signaling patterns amongst bacteria in the wounds. A range of autoinducer-2 activities were detected in the wound samples. Collectively, these data provide new insights into the identity, organization, and behavior of bacteria in chronic wounds. Such information may provide important clues to effective future strategies in wound healing.

Human skin is colonized by bacteria. The development of new genomic microbiological techniques has revealed that the bacterial ecology of human skin is far more complex than previously imagined and includes many fastidious or noncultivable bacterial species which are found on both normal and diseased skin. In nature, the predominant bacterial phenotype on epithelial surfaces is that of organisms organized within a biofilm. This contrasts with the widely held belief that bacteria are planktonic, i.e. free-floating single cells. Biofilms are sessile bacterial communities encased in an extracellular matrix that have a well-developed communication system and can regulate bacterial growth and metabolism, confer resistance to antimicrobials and to host inflammatory cells, and alter host metabolism. Biofilms have been observed on healthy skin and in a number of dermatological conditions, including some that were previously thought not to have an infectious aetiology. Here we review the concept of biofilms and their role in cutaneous health and disease.