Learning Objectives: After reading this article, the physician should be able to:
1. Discuss various pathogens associated with a variety of skin infections.
2. Summarize management strategies for various types of skin and soft-tissue infections.
3. Describe the classification system often used to describe the depth of burn injuries.
Release Date: July 2008
N Engl J Med
Cellulitis is a skin infection involving the dermis and subcutaneous tissue that lacks a clear demarcation from uninvolved skin. Erysipelas is a more superficial skin infection that commonly involves the lymphatic system, and the involved skin is often swollen and clearly demarcated from normal skin.
Skin infections often occur from a disruption in the integrity of the skin, usually from trauma. Investigating the mechanism of injury is often helpful in finding the causative organism. Vibrio vulnificus, for instance, is associated with infection following exposure to sea water while Aeromonas hydrophila is associated with infection following fresh water exposure.
Special consideration must be taken when evaluating cellulitis that involves particular anatomical areas. Periorbital cellulitis, for instance, can be caused by Staphylococcus aureus, pneumococcus, and group A streptococcus. It is more critical, though, to distinguish periorbital cellulitis from the more severe orbital cellulitis, which can be associated with serious complications such as cavernous-sinus thrombosis. Interdigital dermatophytic infections are a common nidus for recurrent cellulitis of the lower extremities, and should be treated with a topical antifungal agent. Group A streptococcus also is a common cause of perianal cellulitis in young children.
Necrotizing skin and soft-tissue infection is an important disease entity that should be distinguished from routine cellulitis. These patients require immediate surgical intervention and broad-spectrum antibiotic therapy. The clinical presentation is often a rapidly progressing infection associated with severe pain, crepitus, and bullae. Necrotizing fasciitis is microbiologically classified as a mixed infection (Type I) or a monobacterial infection with group A streptococci (Type II). Type II infections often lack crepitus. Gas gangrene is often due to Clostridium perfringens, and isolation of Clostridium septicum should raise a suspicion for occult colon cancer.
In most cases of cellulitis, diagnostic studies such as needle aspirates and punch biopsies are not warranted. The diagnosis is based on clinical findings, and in most cases, antimicrobial therapy in the immunocompetent host is directed against Staphylococcus aureus and streptococci. Broader coverage is often warranted in patients with immunocompromise such as chronic diabetic foot or decubitus ulcers.
Multiple studies have revealed that bacteremia is uncommon in patients with community-acquired cellulitis, so blood cultures are not cost-effective when performed in all patients with cellulitis. This article, however, recommends performing them in patients who have cellulitis superimposed on lymphedema, buccal or periorbital cellulitis, cellulitis associated with salt or fresh water, and signs and symptoms suggestive of bacteremia such as chills and high fever.
Similarly, most patients with cellulitis do not routinely require radiographs unless underlying osteomyelitis or subcutaneous gas is suspected. Ultrasonography can be helpful in identifying subcutaneous abscess, and can aid in localization for aspiration and drainage. Magnetic resonance imaging with contrast may provide some clues to the presence of necrotizing fasciitis, but in suspected cases, surgical exploration should not be delayed to obtain radiographic studies.
Initial antimicrobial therapy is dependent on host factors (immunocompetent or immunocompromised) and the circumstance of exposure (animal bite, salt or fresh water exposure). Initial antimicrobial therapy should be given intravenously in patients who have rapidly spreading infection, those with chills and high fever, and in patients with immunocompromise. Antimicrobial therapy for human bites should include coverage for Eikenella corrodens, and for dog and cat bites should cover for Pasteurella multocida. Rates of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) were just beginning to rise when this article was written, so the role of CA-MRSA in skin and soft-tissue infections is underestimated.
Schwartz LR, Balakrishnan C
Emergency Medicine, A Comprehensive Study Guide
2004, 6th ed, pp. 1220–6
Patients with burn injuries often seek care in the emergency department. Although a majority of burn victims are treated as outpatients, it is estimated that burn injuries result in 45,000 hospitalizations and 4,500 deaths each year in the United States. The prevalence of burns is twice as common in men as women and more likely in individuals between 18 and 35. Burn-related mortality is dependent on several variables, and increases with the severity and the size of the burn, age over 65, female gender, and the presence of inhalation injury. The prognosis can be negatively affected by preexisting conditions such as heart disease, diabetes, and acute organ system dysfunction.
Burn size is often calculated by the Rule of Nines or by using the Lund and Browder burn diagram. A simple and fast method of estimating the body surface that has been burned requires using the patient's palm to represent approximately 1% of his body surface area.
Burn depth is reported in first-, second- (superficial and deep partial-thickness), third- (full-thickness burns), and fourth-degree burns. First-degree burns, in contrast to second-degree burns, do not result in blister formation. Second-degree superficial partial-thickness burns do not involve the hair follicles or sweat and sebaceous glands, while deep partial-thickness burns include these structures. The distinction between second-degree deep partial-thickness and third-degree burns may be difficult, as both of these burns are painless. Fourth-degree burns involve structures deeper than the skin, such as subcutaneous fat, muscle, and bone.
Smoke inhalation injuries are commonly associated with fire-related burns, and they contribute to increased mortality. The diagnosis is often made by history and physical findings such as singed nasal hair, soot in the mouth or nose, or wheezing. Initial radiographic evaluation may be normal. Fiberoptic bronchoscopy can be diagnostic of inhalational injury in equivocal cases, and can serve a therapeutic role when used to clear the airways.
In the United States, initial fluid resuscitation for burn victims is most often guided by the Parkland formula. The percentage of involved body surface area used in this formula only takes into account second- and third-degree burns. Half of the total fluid is administered over the first eight hours starting from the time of injury, and the remaining half is given over the subsequent 16 hours.
It is recommended that wounds be initially covered with a clean dry sheet. It is best to avoid using antiseptic dressing because this could make the evaluation of the wounds more difficult for the admitting team. Circumferential burns may predispose the patient to compartment syndrome, which may necessitate escharotomy. Large blisters or those overlying joints should be debrided.
About the LLSA
As part of its continuous certification program, the American Board of Emergency Medicine has developed the Lifelong Learning and Self-Assessment (LLSA) program to promote continuous education of diplomates. Each year, beginning in 2004, 16 to 20 articles are chosen based on the Emergency Medicine Model. A list of these articles can be found on the ABEM web site, www.abem.org.
ABEM is not authorized to confer CME credit for the successful completion of the LLSA test, but it has no objection to physicians participating in such activities. EMN's CME activity, Living with the LLSA, is not affiliated with ABEM's LLSA program, and reading this article and completing the quiz does not count toward ABEM certification. Rather, participants may earn 1 CME credit from the Lippincott Continuing Medical Education Institute, Inc., for each completed EMN quiz.
Dr. Jackson Honored by UC
The University of California, San Diego Alumni Association awarded the Distinguished Service to the University honor to Anthony Jackson, MD, who was an undergraduate biochemistry student there and attended the medical school at UC Irvine. He is now an emergency physician at Memorial Hospital of Gardena in Los Angeles.
Dr. Jackson has worked for several years with organizations like the South Central Gifted Scholars Fund to mentor minority middle and high school students. In partnership with 100 Black Men of Los Angeles and Young Black Scholars Program, Dr. Jackson last December rented vehicles to transport students from the Los Angeles area to attend “A Day at UCSD,” a program he developed and personally funded.
One Arm of ACCORD Study Halted
The National Heart, Lung, and Blood Institute halted one arm of a large, ongoing North American study of diabetes and cardiovascular disease 18 months early due to concerns for participant safety.
The Action to Control Cardiovascular Risk in Diabetes (ACCORD) study enrolled 10,251 adults between 40 and 82 with type 2 diabetes and who were at especially high risk for heart attack, stroke, or dying from cardiovascular disease. As one part of the trial, participants were randomized to either standard (5123 adults) or intensive (5128 adults) blood sugar treatment goals. The study is being conducted at 77 sites nationwide and in Canada.
At the recommendation of the Data and Safety Monitoring Board, an independent advisory group of experts in diabetes, cardiovascular disease, and study-related fields, the NHLBI discontinued the intensive treatment. There were 54 more deaths in the intensive treatment group, revealing increased harm caused by the more aggressive treatment approach. NHLBI director Elizabeth G. Nabel, MD, announced that participants in the intensive treatment group will be treated with the standard treatment moving forward, and that other parts of the study will continue. ACCORD is also examining the effects of treatments for blood pressure and blood lipids. The trial is expected to conclude in June 2009.
CME Participation Instructions
To earn CME credit, you must read the article in Emergency Medicine News, and complete the quiz, answering at least 80 percent of the questions correctly. Mail the completed quiz with your check for $10 payable to the Lippincott Continuing Medical Education Institute, Inc., 770 Township Line Road, Suite 300, Yardley, PA 19067. Only the first entry will be considered for credit, and must be received by Lippincott Continuing Medical Education Institute, Inc., by July 31, 2009. Acknowledgement will be sent to you within six to eight weeks of participation.
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