Alex Cazzaniga

Microscopic and physiologic evidence for biofilm‐associated wound colonization in vivo

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.

Early debridement of second-degree burn wounds enhances the rate of epithelization - An animal model to evaluate burn wound therapies

The purpose of this study was to examine the rate of epithelization of second-degree burn wounds with use of two debridement times (early versus late). Burn wounds were randomly assigned to one of the following treatment groups: (1) control, no debridement, (2) early debridement at 24 hours after burning, or (3) late debridement at 96 hours after burning. Wounds from each treatment group were harvested, incubated to allow separation of the dermis and epidermis, and then examined macroscopically for complete epithelization. On day 7 after burning, the percentage of burn wounds completely epithelized was as follows: nondebrided, 41%, 24-hour early debridement, 75%, and 96-hour late debridement, 22%. Burn wounds that were excised 24 hours after burning enhanced the rate of healing as compared to 96 hour and nondebrided burn wounds.

Long-term efficacy, safety and durability of Juvéderm® XC

Over the last decade, there has been increasing interest in minimally invasive cosmetic treatments, especially for facial rejuvenation. Next to botulinum toxin injection, the injection of soft tissue fillers is the second most frequent minimally invasive procedure performed in the USA. Hyaluronic acid (HA) is the most commonly used dermal filler. One of patients’ main concerns about filler injections pertains to pain and discomfort. Topical anesthetics, nerve blocks, and/or the incorporation of lidocaine to the filler have been applied in order to reduce distress and pain. Despite nerve blocks being an effective form of anesthesia, they may distort the area to be treated, as well as lengthen and complicate the procedure. Studies have shown that the incorporation of lidocaine to HA fillers significantly reduces pain and discomfort. Yet, one of the dilemmas about the addition of lidocaine solution to HA fillers is the possible alteration of the physical characteristics of the product by negatively impacting the efficacy and/or duration of the filler. The concern is that the addition of lidocaine could dilute the product, creating less correction per mL, changing the product’s viscosity and consequently the “lifting” ability. Also, this dilution could reduce the product’s duration. There may be a difference between a physician adding an aqueous solution into a lidocaine-free version of HA and the pre-incorporated lidocaine version of HA. An aqueous solution might dilute the product, while the pre-incorporated powder lidocaine appears to avoid this problem. Juvéderm® XC is manufactured with powder lidocaine 0.3%; it is associated with significantly less injection pain than Juvéderm® and other lidocaine-free versions of HA. Studies have shown that lidocaine enhances treatment comfort and optimizes the injection experience while maintaining a similar safety and effectiveness profile. Regarding the longevity, further study is necessary to determine if there is any difference in durability.

Dermal Fillers: An Update

Injection of dermal fillers is the second most frequent nonsurgical cosmetic procedure performed in the USA. Dermal fillers are an option in the treatment of volume deficiency, scars, and rhytides; facial sculpting; facial contouring; and augmentation of specific anatomical sites such as the lips. The number of injectable dermal fillers available on the market increases yearly. Dermatologists and cosmetic surgeons should regularly review treatment options to provide patients with safe and effective filler options. This paper extensively reviews the properties of the available fillers, such as their rheology, longevity, and adverse effects, and how these properties affect the choice of filler agent for a particular patient or a particular site. Also, trends in dermal filler injections are discussed.

057 Epifluorescent and light microscopic visualization of bacterial microcolonies in acute wound infections – Are these biofilms?

A biofilm is a formation of surface-associated microbial cells that are enclosed in a self produced extracellular polymeric substance matrix. This definition is acceptable for in-vitro research but a clear definition for biofilm-associated diseases has yet to be elucidated. A structural/morphological definition is currently used to define biofilms; additionally, physiological or molecular criteria will allow us to define biofilms in disease infection accurately. Our objective over the past several years has been to characterize and observe bacterial biofilms in wound infections using different wound models. To broaden our current understanding of biofilm morphology in wounds for this study we used epifluorescent and light microscopy to visualize wound pathogenic pseudomonas aeruginosa bacteria in a porcine partial thickness infection model. Three experimental animals were used for this study. After animal preparation, partial thickness wounds were created on the backs of 3 animals. Wounds were then inoculated with 106 colony forming units/ml (CFU/ml) of Pseudomonas aeruginosa and covered for 48 hours to allow bacteria to colonize and infect the wound. Biopsies were obtained from normal skin, wounds before inoculation, wounds at 48 hours and wounds 48 hours after inoculation. Biopsies were processed and stained with Hematoxylin and Eosin for light microscopy and Calcofluor White and Ethidium Bromide for epifluorescence microscopy. Images obtained using epifluorescent and light microscopy demonstrate that bacteria form aggregates of microcolonies. These structures are representative of bacterial biofilms and support the hypothesis that bacteria live as biofilms in wound infection. Although currently there is no established and accepted definition for biofilm associated diseases, we anticipate that more studies looking into physiological changes of these structures will clarify our current understanding of wound infection and treatment.