April 13, 2010 — 一篇刊載於4月1日美國家庭醫學科期刊(American Family Physician)的回顧，指出免疫正常的皮膚及軟組織感染(skin and soft tissue infections，SSTIs)病患的更新版診斷與治療策略，特別是社區感染型抗藥性金黃色葡萄球菌(MRSA)。
Skin and Soft Tissue Infections in Immunocompetent Patients Reviewed
By Laurie Barclay, MD
Medscape Medical News
April 13, 2010 — Updated diagnostic and treatment strategies for immunocompetent patients with skin and soft tissue infections (SSTIs), especially community-acquired methicillin-resistant Staphylococcus aureus (MRSA), are described in a review published in the April 1 issue of American Family Physician.
"Superficial soft tissue infections are increasingly common in the outpatient setting," writes James Owen Breen, MD, from the University of North Carolina at Chapel Hill School of Medicine. "The diagnosis of skin infections increased nearly threefold in U.S. emergency departments from 1993 to 2005. A large increase in community acquired ...MRSA infections has prompted changes in the approach to ...SSTIs."
Because of the rising incidence of SSTIs, family clinicians must be familiar with how to manage these conditions. Complicated SSTIs include those with evidence of systemic toxicity, surgical wound infections; perianal infections; animal or human bites; necrotizing soft tissue infections; and SSTIs in immunocompromised patients.
Types of SSTIs
Purulent types of SSTI include abscess, folliculitis, furuncle, and carbuncle. An abscess is a collection of pus within the dermis, associated with erythema and fluctuance, of polymicrobial cause, often involving skin flora (staphylococci and streptococci) and organisms from adjacent mucous membranes. An abscess is characterized as a complicated SSTI if the perianal or perineal areas are affected.
Folliculitis is defined as purulence limited to the epidermis, usually in body areas prone to friction and heavy perspiration. A furuncle is purulence surrounding the hair follicles and extending to subcutaneous tissue, and a carbuncle is the coalescence of several furuncles. In immunocompetent patients, these types of SSTIs are caused by S aureus.
Nonpurulent SSTIs include cellulitis, erysipelas, and impetigo. Cellulitis has a well-demarcated border of erythema, warmth, edema, and pain, caused by streptococci without abscess formation or staphylococci with abscess. Complications may include lymphangitis, necrotizing infections, or gangrene.
Erysipelas is associated with intense erythema and a well-demarcated, painful plaque caused by beta-hemolytic streptococci. Impetigo is characterized by crusted exudates with pustules or vesicles, often seen in preschool-aged children or under conditions of poor hygiene, high humidity, or warm temperatures.
Treatment Options
The main treatment of uncomplicated abscesses measuring less than 5 cm in diameter is surgical drainage alone. Outcomes are similar when wounds are irrigated with tap water or sterile water.
Fever, tachycardia, hypotension, or other signs of systemic infection are red flags warning of the need for inpatient treatment. For patients with life-threatening or rapidly advancing infections, urgent surgical referral is required.
Local resistance and susceptibility patterns should determine choice of antimicrobial agents when these are indicated. For uncomplicated SSTIs without focal coalescence or trauma, beta-lactam antibiotics are the first-line treatments in settings where suspicion is low for MRSA.
When empiric coverage for MRSA is indicated for uncomplicated SSTIs, oral agents are preferred (eg, tetracyclines, trimethoprim/sulfamethoxazole, and clindamycin). In hospitalized patients, vancomycin is the first-line agent for MRSA. Linezolid, daptomycin, tigecycline, and other newer agents should be given only to patients who are refractory to or cannot tolerate vancomycin.
To date, evidence is insufficient to support use of nasal mupirocin or antibacterial body washes to eradicate the carrier state in patients with MRSA or their contacts. The mainstay of MRSA prevention is proper and frequent handwashing as well as other standard infection-control precautions.
Key Recommendations
Specific key clinical recommendations for practice, and their accompanying level of evidence rating, are as follows:
In patients with uncomplicated SSTIs, wound and blood cultures are not needed because results rarely change management decisions (level of evidence: C, based on retrospective analyses).
For uncomplicated SSTIs with abscesses measuring less than 5 cm in diameter, incision and drainage alone is often curative (level of evidence: A, based on retrospective chart review and randomized, double-blind trials).
For surgical drainage of SSTIs, clinical outcomes are no different for wound irrigation with tap water vs sterile water (level of evidence: A, based on prospective trials from urban pediatric emergency departments).
Clinicians should consider local prevalence and resistance patterns of MRSA and other pathogens when starting empiric antimicrobial therapy for uncomplicated SSTIs (level of evidence: C, based on expert opinion).
Eradicating the MRSA carrier state does not appear to be associated with a lower incidence of clinical MRSA infection (level of evidence: A, based on a randomized, double-blind trial and Cochrane review).
"Standard infection control precautions should be implemented and encouraged for all patients in ambulatory and inpatient settings, including proper and frequent handwashing, use of gloves when managing wounds, and contact precautions (e.g., use of gowns and gloves, grouping patients with similar infections) for patients with known or suspected MRSA infections," Dr. Breen concludes. "To prevent SSTIs, current consensus guidelines support proper foot care among patients with diabetes, tinea pedis, or pedal edema from venous insufficiency or lymphedema."
Dr. Breen has disclosed no relevant financial relationships.
