Cesarean delivery is one of the most commonly performed surgical procedures. In 2015, 1.27 million infants born in the United States, representing 32% of all US births, were born by cesarean delivery.1 Cesarean delivery is the most important risk factor for infection in the postpartum period. Surveillance for postcesarean surgical site infection (SSI) conducted in the United States between 2006 and 2008 demonstrated an overall SSI rate of approximately 2%,2 but infection rates of up to 20% have been observed in some clinical studies.3 Several factors have been associated with the development of postcesarean SSI, including emergency surgery, onset of labor prior to delivery, membrane rupture prior to surgery, surgical wound class, procedure duration, and obesity.2,4 Among these, obesity is one of the most commonly encountered risk factors. In 2014, 24.8% of women who gave birth in the United States were obese (body mass index >29.9).5 Thus, an estimated 315 000 infants are born to obese women by cesarean delivery in the United States each year. Preoperative antimicrobial prophylaxis has been associated with reductions in postcesarean SSI,6 and in 2011 the American College of Obstetricians and Gynecologists recommended use of preoperative antimicrobial prophylaxis in all cesarean deliveries.7 Despite this intervention, rates of infection following cesarean delivery may still exceed 10%.3 In this issue of JAMA, Valent and colleagues8 report the results of a randomized clinical trial of oral antimicrobial prophylaxis during the first 48 hours after surgery for prevention of postcesarean SSI among obese women. In this single-center study, obese women (prepregnancy body mass index ≥30) admitted to the labor unit for delivery via cesarean method were enrolled, stratified by predelivery membrane status, and randomized to receive either oral cephalexin (500 mg) plus metronidazole (500 mg) (n = 202) or placebo (n = 201) every 8 hours for a total of 6 doses after delivery. All patients received a single 2-g intravenous dose of cefazolin prior to surgical incision. The women were evaluated at 2 and 6 weeks after surgery for the primary outcome of any superficial incisional, deep incisional, or organ/space SSI within 30 days of surgery. As anticipated, the overall incidence of SSI was high (10.9%) among these high-risk study participants, and even higher rates were observed among those with ruptured membranes (19.8% of 126 women) vs among those with intact membranes (6.9% of 277 women). Among those randomized to receive cephalexin-metronidazole prophylaxis in the first 48 hours of the postpartum period, the incidence of SSI was significantly lower than that observed among placebo recipients (6.4% and 15.4%, respectively P = .01). The results of this study suggest that a 2-day course of oral cephalexin and metronidazole after cesarean delivery may be an effective strategy to prevent postcesarean SSI among obese women. When determining if and how the results of this study should alter current clinical practice, it is important to recognize that the results of this study are quite different from those of several previous studies conducted in other surgical patient populations in which no benefit from postoperative antimicrobial prophylaxis was found and on which current clinical guidelines for antimicrobial prophylaxis are based.9 The explanation for this difference may be as simple as the identification in the current study of a very specific, high-risk group of patients for which the intervention is effective. However, several questions are worthy of additional consideration and study. First, are the findings generalizable to obese women undergoingcesareandeliveryinothersettings?Asasingle-centerstudy, the possibility of site-specific confounders exists. Additionally, given that participant enrollment for this study began almost 7 years ago and extended over a 5-year period, one consideration is whether the surgical practices and SSI prevention measures used during the study are representative of those that are widely used today.10 For example, were glycemic control, maintenance of normothermia, and preoperative bathing routinely implemented? Would the same benefit be seen among obese women who receive a higher preoperative dose of cefazolin (ie, 3 g), as recommended in current clinical practice guidelines?9 Second, is this strategy appropriate for all obese women or isthereamorespecificsubsetofwomeninwhomitshouldbeconsidered?Theauthorsconcludedthat12womenneedtobetreated to prevent 1 SSI. In other words, 11 of 12 women would not benefit from the intervention. While this number needed to treat is certainly less than that for many commonly accepted health interventions, it begs the question as to whether further specification of the target population is possible. Although the study was not powered or designed to determine subpopulations within which the strategy is most appropriate and effective, the post hoc analyses provide some interesting and potentially relevant data. In a subgroup analysis of women with ruptured membranes, assignment to the intervention group of the study was associated with a significantly lower SSI rate (9.5% vs 30.2%; P = .008). Among women with intact membranes, there was no significant difference in SSI rates between study groups (5% vs 8.7%). Related article page 1026 Opinion

中文翻译：

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肥胖女性剖宫产术后抗生素预防

剖腹产是最常用的外科手术之一。2015 年，美国有 127 万婴儿通过剖宫产出生，占美国所有新生儿的 32%。1 剖宫产是产后感染最重要的危险因素。2006 年至 2008 年在美国进行的剖宫产手术部位感染 (SSI) 监测表明，总体 SSI 发生率约为 2%，2 但在一些临床研究中观察到感染率高达 20%。 3与剖宫产后 SSI 的发展相关，包括急诊手术、分娩前分娩、手术前胎膜破裂、手术伤口类别、手术持续时间和肥胖。 2,4 其中，肥胖是最常见的风险之一因素。2014 年，在美国，24.8% 的分娩妇女肥胖（体重指数 >29.9）。5 因此，估计美国每年有 315 000 名婴儿通过剖宫产分娩。术前抗生素预防与剖宫产后 SSI 的减少有关，6 2011 年，美国妇产科学院建议在所有剖宫产中使用术前抗生素预防。 7 尽管有这种干预，剖宫产后的感染率仍可能超过 10% .3 在本期 JAMA 中，Valent 及其同事 8 报告了一项随机临床试验的结果，该试验在手术后的前 48 小时内进行口服抗菌素预防，以预防肥胖女性剖宫产后 SSI。在这项单中心研究中，纳入通过剖宫产分娩的肥胖妇女（孕前体重指数 ≥ 30），根据分娩前胎膜状态进行分层，并随机接受口服头孢氨苄（500 mg）加甲硝唑（500 mg）（n = 202） ) 或安慰剂 (n = 201) 每 8 小时给药一次，共给药 6 剂。所有患者在手术切口前均接受单次 2 g 静脉内剂量的头孢唑啉。在手术后 2 周和 6 周对这些女性进行评估，以确定手术后 30 天内任何浅表切口、深切口或器官/空间 SSI 的主要结果。正如预期的那样，在这些高风险研究参与者中，SSI 的总体发生率很高 (10.9%)，并且在膜破裂者（126 名女性中的 19.8%）中观察到的发生率甚至高于膜完整者（6.9%）。 277 名女性）。在产后最初 48 小时内随机接受头孢氨苄-甲硝唑预防的患者中，SSI 的发生率显着低于安慰剂接受者中观察到的发生率（分别为 6.4% 和 15.4%，P = .01）。这项研究的结果表明，剖宫产后 2 天的口服头孢氨苄和甲硝唑疗程可能是预防肥胖女性剖宫产后 SSI 的有效策略。在确定本研究的结果是否以及如何改变当前的临床实践时，重要的是要认识到本研究的结果与之前在其他手术患者人群中进行的几项研究的结果大不相同，在这些研究中，术后预防性抗生素治疗没有益处被发现，并且当前的抗菌预防临床指南是基于该指南。9 对这种差异的解释可能很简单，就像当前研究中识别出干预有效的非常具体的高风险患者群体一样。然而，有几个问题值得进一步考虑和研究。首先，这些发现是否可以推广到在其他环境中接受剖宫产和分娩的肥胖女性？作为单一中心研究，存在特定地点混杂因素的可能性。此外，鉴于这项研究的参与者招募开始于近 7 年前并延长了 5 年，一个考虑因素是研究期间使用的外科手术和 SSI 预防措施是否代表当今广泛使用的措施。 10 对于例如，血糖控制、维持正常体温、和术前洗澡有规律吗？按照当前临床实践指南的建议，在术前接受较高剂量头孢唑林（即 3 克）的肥胖女性中是否会看到同样的益处？9 其次，该策略是否适用于所有肥胖女性，或者是否应该考虑更具体的女性亚组？作者得出结论，12 名女性需要接受治疗以预防 1 SSI。换句话说，12 名妇女中有 11 名不会从干预中受益。虽然这个需要治疗的人数肯定少于许多普遍接受的健康干预措施，但它引出了一个问题，即是否有可能进一步指定目标人群。尽管该研究的效力或设计不是为了确定该策略最合适和最有效的亚群，事后分析提供了一些有趣且可能相关的数据。在对破膜妇女的亚组分析中，分配到研究的干预组与显着较低的 SSI 率相关（9.5% 对 30.2%；P = .008）。在膜完整的女性中，研究组之间的 SSI 率没有显着差异（5% 对 8.7%）。相关文章第1026页意见