阿莫西林是常用的抗生素，常用來治療輕微肺部感染。最新研究發(fā)現(xiàn)，抗生素對輕微肺部感染的持續(xù)咳嗽患者治療無效，即使是在老年患者。本研究發(fā)表在12月19日在線出版的《柳葉刀傳染疾病》。

　　這是迄今抗生素治療下呼吸道感染最大的以安慰劑對照的隨機臨床試驗。來自歐洲12個國家2000余例急性下呼吸道感染患者（持續(xù)咳嗽≤28天）參與了此項研究。研究隨機分為兩組，一組接受抗生素治療（N=1038），另一組接受安慰劑治療（N=1023），安慰劑組使用糖片的惰性治療形式，一天三次，一個療程服用七天。

　　抗生素肺部感染

　　研究發(fā)現(xiàn)兩組患者在疾病嚴重程度和持續(xù)時間上幾乎沒有差異，即使在老年患者（年齡在60歲或60歲以上的患者）也是如此。領導該研究的英國南安普敦大學PaulLittle教授說：“與不服藥患者相比，服用阿莫西林的患者并不會更快地恢復或減輕癥狀。事實上，對疑似未患肺炎的患者使用抗生素阿莫西林治療呼吸道感染，非但不利反而有害。按照初級處方（大多是基層醫(yī)生開出），過量使用抗生素，尤其當它們無效時，會導致出現(xiàn)耐藥性且有副作用，如腹瀉、皮疹和嘔吐。我們的研究結果表明，患者自己就會恢復好。但抗生素對少數(shù)患者會有效，問題是如何找出受益于抗生素的人，這仍具挑戰(zhàn)性。”

　　歐洲疾病預防與控制中心(ECDC)最近發(fā)表聲明稱，抗生素耐藥性仍然是全世界公共健康的一個主要威脅，很大程度上是由于濫用抗生素。肺部感染，也稱下呼吸道感染，是發(fā)達國家基層醫(yī)療單位最常見的急性疾病。對下呼吸道感染患者是否應該用抗生素治療現(xiàn)在仍然存在爭議，尤其是在年長患者，因為大多數(shù)下呼吸道感染主要是病毒感染所致。但專家警告稱，若懷疑是肺炎，出于嚴重性考慮，仍應使用抗生素。

　　在一篇評論中，來自瑞士巴塞爾大學的菲利普教授指出：“Little和他的同事們提供了令人信服的數(shù)據(jù)，應該鼓勵基層醫(yī)療單位的醫(yī)生，在低風險疑似未患肺炎的患者中避免使用抗生素治療。然而這種一刀切的方式能否能得到進一步改善呢？或許檢測細菌感染的特殊血液標志物，以識別那些少數(shù)能受益于抗生素的人是一種更優(yōu)方法，既能避免副作用，又能防止出現(xiàn)抗生素耐藥。”

　　皇家學院全科醫(yī)生邁克爾.摩爾博士，也是這項研究的合著作者，他也表示：“重要的是全科醫(yī)生們清楚地知道，他們應不應該給病人開抗生素，從而減少社區(qū)細菌性耐藥的發(fā)生。

　　Amoxicillin for acute lower-respiratory-tract infection in primary care when pneumonia is not suspected: a 12-country, randomised, placebo-controlled trial

　　 Background

　　Lower-respiratory-tract infection is one of the most common acute illnesses managed in primary care. Few placebo-controlled studies of antibiotics have been done, and overall effectiveness (particularly in subgroups such as older people) is debated. We aimed to compare the benefits and harms of amoxicillin for acute lower-respiratory-tract infection with those of placebo both overall and in patients aged 60 years or older.

　　Methods

　　Patients older than 18 years with acute lower-respiratory-tract infections (cough of ≤28 days' duration) in whom pneumonia was not suspected were randomly assigned (1:1) to either amoxicillin (1 g three times daily for 7 days) or placebo by computer-generated random numbers. Our primary outcome was duration of symptoms rated “moderately bad” or worse. Secondary outcomes were symptom severity in days 2–4 and new or worsening symptoms. Investigators and patients were masked to treatment allocation. This trial is registered with EudraCT (2007-001586-15), UKCRN Portfolio (ID 4175), ISRCTN (52261229), and FWO (G.0274.08N).

　　Findings

　　1038 patients were assigned to the amoxicillin group and 1023 to the placebo group. Neither duration of symptoms rated “moderately bad” or worse (hazard ratio 1·06, 95% CI 0·96–1·18; p=0·229) nor mean symptom severity (1·69 with placebo vs 1·62 with amoxicillin; difference ??0·07 [95% CI ??0·15 to 0·007]; p=0·074) differed significantly between groups. New or worsening symptoms were significantly less common in the amoxicillin group than in the placebo group (162 [15·9%] of 1021 patients vs 194 [19·3%] of 1006; p=0·043; number needed to treat 30). Cases of nausea, rash, or diarrhoea were significantly more common in the amoxicillin group than in the placebo group (number needed to harm 21, 95% CI 11–174; p=0·025), and one case of anaphylaxis was noted with amoxicillin. Two patients in the placebo group and one in the amoxicillin group needed to be admitted to hospital; no study-related deaths were noted. We noted no evidence of selective benefit in patients aged 60 years or older (n=595).

　　Interpretation

　　When pneumonia is not suspected clinically, amoxicillin provides little benefit for acute lower-respiratory-tract infection in primary care both overall and in patients aged 60 years or more, and causes slight harms.

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