Skin and soft tissue infections

Primary skin infections (ie, pyodermas) typically are initiated by some breach in the epidermis, resulting in infection by organisms, such as Streptococcus pyogenes and Staphylococcus aureus, that normally colonize the skin. Host-associated factors, such as immunosuppression, vasculopathy, neuropathy, or decreased lymphatic drainage, may predispose to skin infection. The clinical syndromes associated with skin infections are often characteristic and are defined most simplistically by anatomic distribution. Although often mild and self-limited, skin infections can be more aggressive and involve deeper structures, including fascia and muscle. This article discusses skin and soft tissue infections, including impetigo, hair follicle-associated infections (ie, folliculitis, furuncles, and carbuncles) erysipelas, cellulitis, necrotizing fasciitis, pyomyositis, septic bursitis, and tenosynovitis.     

Skin and soft tissue infections in older adults

Skin and soft tissue infections (SSTIs) are a common cause of morbidity in older patients. Because of changes in skin consistency, immunosenescence, and the presence of underlying skin conditions and comorbid conditions, elderly persons are at high risk for SSTIs. Specific community- and hospital-associated SSTIs are reviewed in this article with particular emphasis on the epidemiology, prevention, risk factors, and treatment of SSTIs in older patients.     

Skin and soft tissue infections in injection drug users

Skin and soft tissue infections are the most common cause for hospital admission of injection drug users. Cutaneous and subcutaneous abscesses are the most frequent type of SSTI and occur most commonly when drug users are no longer able to inject intravenously and resort to injection directly into skin or muscle. Abscesses may be difficult to differentiate from uncomplicated cellulitis or may be confused with pseudoaneurysms, hematoma, phlegmon, or thrombosed vein. Special studies, including ultrasonography; CT scans, and MR imaging; or careful incision and inspection may be necessary to clarify the extent of infection and the presence of abscess. These procedures may also help differentiate a subcutaneous abscess from a vascular structure. Uncomplicated cellulitis most commonly responds to antibiotic therapy directed toward Staphylococcus aureus and Streptococcus spp. In several recent studies, cutaneous and subcutaneous abscesses have been found to be caused by polymicrobial infections and to include anaerobic organisms as well as aerobic gram-positive cocci in a little more than 50% of cases. Complete, often repeated, incision and drainage is a prerequisite for successful outcome in these cases. Complications of SSTI are many and are potentially life threatening. They include direct extension of subcutaneous abscess into vital areas or structures, necrotizing fasciitis and myositis, bacteremia, and sepsis. An outbreak of a highly lethal SSTI that recently occurred in Scotland, Ireland, and England seems to have resulted from infection with Clostridia spp, including C. novyi and C. perfringens. A rare but well-documented SSTI in injection drug users is pyomyositis, an abscess-forming infection of skeletal muscle. More than 20 cases have been reported in temperate climates to date. Although not life-threatening, chronic cutaneous venous ulcers of the lower extremities are common and debilitating, requiring long-term multidisciplinary care for successful healing.     

Skin and soft tissue infections in the transplant population

Solid organ and hematopoietic stem cell transplant recipients are more likely to develop skin and soft tissue infections, which may be caused by common or atypical pathogens. Skin and soft tissue anatomic abnormalities may act as portals of entry for infection, and may result from surgery, venous access, immunosuppressive medications, and other etiologies. Systemic infection may sometimes be recognized by investigation of skin manifestations. Many noninfectious processes of the skin and soft tissues can mimic infection, complicating the diagnosis. Prompt dermatologic consultation and skin biopsy are essential in this vulnerable population. Treatment of infection in transplant recipients may necessitate reduction of immunosuppression, in addition to other adjunctive therapies. Interesting and important new findings about skin and soft tissue infections in transplant recipients are the focus of this review.     

Skin and soft tissue infections and envenomations acquired at the beach

Millions of people spend vacation and leisure time on the shores of the lakes and oceans of North America. Many others are employed in water-related industries. In doing so, they potentially expose themselves to infections and envenomations that other people do not even consider when making their plans for leisure time activities or in going to work each day. This article reviews some common and uncommon beach-related infections and envenomations that can affect the skin and soft tissues of people frequenting the shores and beaches of North America. Physicians are thereby provided with a guide to such skin and soft tissue injuries and infections and will be better able to recognize and treat these maladies associated with recreational and occupational activities.     

Necrotizing soft tissue infections

Necrotizing soft tissue infections are characterized by necrosis of skin and associated structures. Despite advances in the diagnosis and treatment of these infections, the mortality remains high. There have been increasing reports of necrotizing fasciitis caused by group A Streptococcus over the past decade. Recent information supports the role of superantigens in the pathogenesis of this infection. The approach to management requires expeditious evaluation with early surgery and appropriate antimicrobial agents. Limited data suggest that surgical debridement may be delayed in selected patients until the patient is stable by the use of intravenous immunoglobulin, which can neutralize superantigens.     

Skin and soft tissue infections among HIV-infected persons in the late combination antiretroviral therapy era

Skin and soft tissue infections (SSTIs) occur at higher rates among HIV-infected persons, but current trends and risk factors are largely undefined. We evaluated SSTIs among a prospective cohort of HIV-infected persons during the late combination antiretroviral therapy (cART) era (2006-2010). Of the 1918 HIV-infected persons evaluated, 379 (20%) developed an SSTI during a median of 3.7 years of follow-up; of these, 118 (31%) developed at least one recurrent SSTI. The incidence rate of SSTIs was 101 (95% confidence interval [CI] 93-109) cases per 1000 person-years, and rates did not significantly change during the study period. Compared with not receiving cART and having an HIV RNA level >1000 copies/mL, patients receiving cART with an HIV RNA level <1000 copies/mL had a reduced risk of an SSTI (hazard ratio 0.64, 95% CI 0.48-0.86, P < 0.01). In summary, initial and recurrent SSTIs are common among HIV-infected persons, and HIV control is associated with a lower risk of SSTIs.     

Rapidly progressive soft tissue infections

Skin and soft tissue infections are among the most common reasons for people to seek medical advice. They also represent one of the most common indications for antimicrobial therapy and account for approximately 7-10% of hospitalisations in North America. Although non-limb and non-life threatening infections may be treated on an out-patient basis with oral antibiotics, patients with more serious acute skin and soft tissue infections may require admission to hospital for management; this decision is especially true if the infection is rapidly progressive. We provide a concise overview of the differential diagnosis and approach to management of community-acquired rapidly progressive skin and soft tissue infections.     

Skin and soft tissue infections in hospitalized and critically ill patients: a nationwide population-based study

Background  

The proportional distributions of various skin and soft tissue infections (SSTIs) with/without intensive care are unclear. Among SSTI patients, the prevalence and significance of complicating factors, such as comorbidities and infections other than skin/soft tissue (non-SST infections), remain poorly understood. We conducted this population-based study to characterize hospitalized SSTI patients with/without intensive care and to identify factors associated with patient outcome.     

Skin and soft tissue infection: necrotizing fasciitis

The incidence of necrotizing fasciitis has increased in the past decade as a result of the resurgence severe group A streptococcal infection. Mortality has remained unchanged over the past 60 years, supporting the notion that immune modulators, such as intravenous immunoglobulin, are required to alter the physiological process during the early stages of infection.