回顧免疫正常病患的皮膚和軟組織感染


  【24drs.com】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)。
  
  北卡羅來納大學教堂山分校醫學院James Owen Breen醫師寫道,門診病患越來越多表面軟組織感染案例,從1993-2005年,美國的皮膚感染急診案例增加將近3倍,社區感染型MRSA大量增加,造成了治療SSTIs方法的改變。
  
  因為SSTIs的發生率增加,家庭醫師必須熟悉如何處置這些狀況,複雜的SSTIs包括全身性毒性的證據,手術傷口感染;肛周感染;動物或人咬傷;壞死性軟組織感染;以及免疫功能受損病患的SSTIs。
  
  【SSTIs的類型】
  SSTI的化膿類型包括膿腫、毛囊炎、癤與膿瘡。膿腫是真皮內化膿,與紅斑和膿瘍形成有關,多種微生物引起,通常包括皮膚菌叢(葡萄球菌和鏈球菌)以及鄰近周邊黏膜的有機體,如果肛周或會陰週邊區域感染,膿腫即為複雜性SSTI的特徵。
  
  毛囊炎定義是化膿位置侷限在表皮,通常傾向發生在磨擦或多汗的身體部位。癤是毛囊週邊化膿且擴散到皮下組織,膿瘡是多個癤發生在一起,在免疫正常的病患,這些類型的SSTIs是由金黃色葡萄球菌引起。
  
  非化膿性的SSTIs包括蜂窩性組織炎、丹毒以及膿疱病。蜂窩性組織炎有一個邊緣相當清楚的紅腫熱痛患部,由鏈球菌引起但無化膿、或者葡萄球菌引起而有化膿,併發症包括淋巴管炎、壞死性感染、或壞疽。
  
  丹毒和嚴重紅斑有關且有明確邊緣,β-溶血型鏈球菌引起的疼痛斑點。膿疱病的特徵是形成痂皮的滲出物,有小膿疱或小水疱,通常出現在學齡前孩童或者衛生不佳、溼度高、溫暖的情況。
  
  【治療選項】
  直徑小於5公分的無併發症膿腫,主要治療方式為手術引流,用自來水或滅菌水沖洗傷口的結果差不多。
  
  發燒、心搏過速、低血壓或其他全身性感染症狀,都是需要住院治療的警訊,對於有生命危險或感染迅速惡化的病患,需要緊急手術。
  
  應確認當地的細菌抗藥性和敏感性模式,以選擇適用的抗生素。對於無併發症SSTIs且無局部癒合或創傷的病患,β-內醯胺抗生素是MRSA可能性低者的第一線治療藥物。
  
  若要以經驗性療法治療無併發症SSTIs的MRSA,建議使用口服藥物(例如tetracyclines、trimethoprim/sulfamethoxazole以及clindamycin),對於住院病患,MRSA的第一線藥物為vancomycin。 Linezolid、daptomycin、tigecycline以及其他新藥只可用於vancomycin無效或無法耐受vancomycin的病患。
  
  到目前為止,證據並不支持使用鼻用型mupirocin或抗菌身體洗劑來除去病患身上的或接觸物品上的MRSA。預防MRSA的主要方式還是適當的經常洗手,以及其他標準的感染控制注意事項。
  
  【主要建議】
  實務上的特殊關鍵臨床建議,以及相關的證據等級如下:
  * 對於無併發症的SSTIs病患,不需要傷口和血液培養,因為培養結果很少會改變處置決定(證據等級:C,根據回溯分析)。
  * 對於無併發症之SSTIs、直徑小於5公分的膿腫 ,通常只要切開引流即可治癒(證據等級:A,根據回溯病歷回顧與隨機雙盲試驗)。
  * 對於SSTIs的手術引流,使用自來水和滅菌水進行傷口灌洗的臨床結果沒有差異(證據等級:A,根據都市小兒急診的前瞻試驗)。
  * 醫師在開始使用經驗性抗生素治療無併發症的SSTIs時,應考慮地區盛行率以及MRSA與其他病原菌之抗藥性模式(證據等級:C,根據專家意見)。
  * 除掉MRSA帶原狀態並不會降低臨床MRSA感染的發生率(證據等級:A,根據一篇隨機雙盲試驗與Cochrane資料庫回顧)。
  
  Breen醫師結論表示,應執行標準化的感染控制注意事項,並鼓勵所有可行動的病患與住院病患執行,還要包括適當且規律的洗手,對於已知或疑似MRSA感染的病患,處置傷口時要戴手套,接觸時要遵守注意事項(例如戴頭套或手套,根據相似的感染分類病患),為了預防SSTIs,目前的共識指引支持對糖尿病、足癬、靜脈曲張或淋巴水腫導致足部水腫之病患進行適當的足部照護。
  
  Breen醫師宣告沒有相關財務關係。

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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