回顾免疫正常病患的皮肤和软组织感染


  【24drs.com】April 13, 2010 — 一篇刊载于4月1日美国家庭医学科期刊(American Family Physician)的回顾,指出免疫正常的皮肤及软组织感染(skin and soft tissue infections,SSTIs)病患的更新版诊断与治疗策略,特别是社区感染型抗药性金黄色葡萄球菌(MRSA)。
  
  北卡罗来纳大学教堂山分校医学院James Owen Breen医师写道,门诊病患越来越多表面软组织感染案例,从1993-2005年,美国的皮肤感染急诊案例增加将近3倍,社区感染型MRSA大量增加,造成了治疗SSTIs方法的改变。
  
  因为SSTIs的发生率增加,家庭医师必须熟悉如何处置这些状况,复杂的SSTIs包括全身性毒性的证据,手术伤口感染;肛周感染;动物或人咬伤;坏死性软组织感染;以及免疫功能受损病患的SSTIs。
  
  【SSTIs的类型】
  SSTI的化脓类型包括脓肿、毛囊炎、疖与脓疮。脓肿是真皮内化脓,与红斑和脓疡形成有关,多种微生物引起,通常包括皮肤菌丛(葡萄球菌和链球菌)以及邻近周边黏膜的有机体,如果肛周或会阴外围区域感染,脓肿即为复杂性SSTI的特征。
  
  毛囊炎定义是化脓位置局限在表皮,通常倾向发生在磨擦或多汗的身体部位。疖是毛囊外围化脓且扩散到皮下组织,脓疮是多个疖发生在一起,在免疫正常的病患,这些类型的SSTIs是由金黄色葡萄球菌引起。
  
  非化脓性的SSTIs包括蜂窝性组织炎、丹毒以及脓疱病。蜂窝性组织炎有一个边缘相当清楚的红肿热痛患部,由链球菌引起但无化脓、或者葡萄球菌引起而有化脓,并发症包括淋巴管炎、坏死性感染、或坏疽。
  
  丹毒和严重红斑有关且有明确边缘,β-溶血型链球菌引起的疼痛斑点。脓疱病的特征是形成痂皮的渗出物,有小脓疱或小水疱,通常出现在学龄前孩童或者卫生不佳、湿度高、温暖的情况。
  
  【治疗选项】
  直径小于5公分的无并发症脓肿,主要治疗方式为手术引流,用自来水或灭菌水冲洗伤口的结果差不多。
  
  发烧、心搏过速、低血压或其它全身性感染症状,都是需要住院治疗的警讯,对于有生命危险或感染迅速恶化的病患,需要紧急手术。
  
  应确认当地的细菌抗药性和敏感性模式,以选择适用的抗生素。对于无并发症SSTIs且无局部愈合或创伤的病患,β-内醯胺抗生素是MRSA可能性低者的第一线治疗药物。
  
  若要以经验性疗法治疗无并发症SSTIs的MRSA,建议使用口服药物(例如tetracyclines、trimethoprim/sulfamethoxazole以及clindamycin),对于住院病患,MRSA的第一线药物为vancomycin。 Linezolid、daptomycin、tigecycline以及其它新药只可用于vancomycin无效或无法耐受vancomycin的病患。
  
  到目前为止,证据并不支持使用鼻用型mupirocin或抗菌身体洗剂来除去病患身上的或接触物品上的MRSA。预防MRSA的主要方式还是适当的经常洗手,以及其它标准的感染控制注意事项。
  
  【主要建议】
  实务上的特殊关键临床建议,以及相关的证据等级如下:
  * 对于无并发症的SSTIs病患,不需要伤口和血液培养,因为培养结果很少会改变处置决定(证据等级:C,根据回溯分析)。
  * 对于无并发症之SSTIs、直径小于5公分的脓肿 ,通常只要切开引流即可治癒(证据等级:A,根据回溯病历回顾与随机双盲试验)。
  * 对于SSTIs的手术引流,使用自来水和灭菌水进行伤口灌洗的临床结果没有差异(证据等级:A,根据都市小儿急诊的前瞻试验)。
  * 医师在开始使用经验性抗生素治疗无并发症的SSTIs时,应考虑地区盛行率以及MRSA与其它病原菌之抗药性模式(证据等级:C,根据专家意见)。
  * 除掉MRSA带原状态并不会降低临床MRSA感染的发生率(证据等级:A,根据一篇随机双盲试验与Cochrane资料库回顾)。
  
  Breen医师结论表示,应执行标准化的感染控制注意事项,并鼓励所有可行动的病患与住院病患执行,还要包括适当且规律的洗手,对于已知或疑似MRSA感染的病患,处置伤口时要戴手套,接触时要遵守注意事项(例如戴头套或手套,根据相似的感染分类病患),为了预防SSTIs,目前的共识指引支持对糖尿病、足癣、静脉曲张或淋巴水肿导致足部水肿之病患进行适当的足部照护。
  
  Breen医师宣告没有相关财务关系。

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.

Am Fam Physician. 2010;81:893-899.

    
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