摘要目的:探讨腰椎融合术后手术部位感染患者的病原菌分布特征及其与治疗措施、临床预后的关系。方法:回顾性分析2010年1月至2024年1月于北京大学人民医院脊柱外科行腰椎融合术后确诊手术部位感染的228例患者资料。根据首次清创术中组织病原菌培养及革兰染色结果，将患者分为G+菌感染组、G-菌感染组和混合感染组。比较三组的病原菌分布特征和实验室检查感染相关指标。观察三组治疗措施（包括清创次数和静脉抗生素疗程）及感染控制后1个月、3个月、1年时的感染复发率，以Oswestry功能障碍指数（Oswestry disability index，ODI）评价术后功能情况及三组重度功能障碍患者构成比。结果:228例患者中G+菌感染116例（50.9%）、G-菌感染68例（29.8%）、混合感染44例（19.3%）。三组患者年龄、体质指数、糖尿病、手术时间及术中出血量的差异有统计学意义（ P<0.05）；混合感染组年龄为（65.7±9.0）岁，体质指数>30 kg/m 2、糖尿病、手术时间>4 h及术中出血量>500 ml患者的构成比分别为40.9%、52.3%、40.9%和45.5%，均高于其他两组。G+菌感染组以金黄色葡萄球菌为主，占62.1%（72/116）；G-菌感染组以大肠埃希菌和肺炎克雷伯菌为主，分别占44.1%（30/68）和26.5%（18/68）；混合感染组以G+菌合并G-菌感染为主，占81.8%（36/44）。三组感染发生时间、红细胞沉降率、C反应蛋白及白细胞计数的差异无统计学意义（ P>0.05）；混合感染组耐甲氧西林金黄色葡萄球菌检出率为36.4%（16/44），高于G+菌感染组的18.1%（21/116），差异有统计学意义（χ 2=5.983， P=0.014）。三组清创次数及静脉抗生素疗程的差异有统计学意义（ P<0.05）。其中混合感染组清创次数≥2次和静脉抗生素疗程>50 d的患者构成比分别为61.4%和70.5%，均高于G+菌感染组的28.4%、35.3%及G-菌感染组的32.4%、30.9%；三组内固定取出率（分别为15.5%、17.6%、22.7%）的差异无统计学意义（χ 2=1.147， P=0.564）。三组感染控制后1个月、3个月的感染复发率（分别为6.9%、7.4%、9.1%；8.6%、8.8%、13.6%）差异无统计学意义（χ 2=0.224， P=0.894；χ 2=0.996， P=0.608）；1年时感染复发率（分别为10.3%、11.8%、27.3%）及术后1年ODI（分别为10.3%、8.8%、25.0%）的差异有统计学意义（χ 2=7.990， P=0.018；χ 2=10.078， P=0.039），混合感染组1年感染复发率和重度功能障碍比例分别为27.3%和25.0%，均高于其他两组。 结论:腰椎融合术后手术部位感染以G+菌感染为主，混合感染患者耐甲氧西林金黄色葡萄球菌检出率更高，且与更多清创次数、更长的静脉抗生素使用时间、更高的1年感染复发率及较差功能预后相关。高龄、肥胖、糖尿病、手术时间延长及术中出血量增加可能与混合感染发生有关。

abstractsObjective:To investigate the pathogen distribution characteristics of surgical site infection after lumbar fusion and their associations with treatment strategies and clinical outcomes.Methods:Clinical data of 228 patients diagnosed with surgical site infection after lumbar fusion in the Department of Spine Surgery, Peking University People's Hospital, from January 2010 to January 2024 were retrospectively analyzed. According to the results of pathogen culture and Gram staining of tissue samples obtained during the first debridement, patients were divided into the Gram-positive infection group, Gram-negative infection group, and mixed infection group. The pathogen distribution characteristics and infection-related laboratory indicators were compared among the three groups. Treatment measures, including the number of debridements and duration of intravenous antibiotic therapy, were recorded. Infection recurrence rates at 1 month, 3 months, and 1 year after infection control were analyzed. Postoperative functional status was evaluated using the Oswestry disability index (ODI), and the proportion of patients with severe disability was compared among the three groups.Results:Among the 228 patients, 116 cases (50.9%) were classified into the Gram-positive infection group, 68 cases (29.8%) into the Gram-negative infection group, and 44 cases (19.3%) into the mixed infection group. Significant differences were observed among the three groups in age, body mass index, diabetes mellitus, operative time, and intraoperative blood loss ( P<0.05). In the mixed infection group, the mean age was 65.7±9.0 years, and the proportions of patients with body mass index >30 kg/m 2, diabetes mellitus, operative time >4 h, and intraoperative blood loss >500 ml were 40.9%, 52.3%, 40.9%, and 45.5%, respectively, all of which were higher than those in the other two groups. In the Gram-positive infection group, Staphylococcus aureus was the predominant pathogen, accounting for 62.1% (72/116). In the Gram-negative infection group, Escherichia coli and Klebsiella pneumoniae were the main pathogens, accounting for 44.1% (30/68) and 26.5% (18/68), respectively. In the mixed infection group, combined Gram-positive and Gram-negative bacterial infection was the most common type, accounting for 81.8% (36/44). There were no significant differences among the three groups in infection onset time, erythrocyte sedimentation rate, C-reactive protein level, or white blood cell count ( P>0.05). The detection rate of methicillin-resistant Staphylococcus aureus in the mixed infection group was 36.4% (16/44), which was significantly higher than that in the Gram-positive infection group [18.1% (21/116), χ 2=5.983, P=0.014]. Significant differences were found among the three groups in the number of debridements and duration of intravenous antibiotic therapy ( P<0.05). The proportions of patients requiring ≥2 debridements and >50 days of intravenous antibiotic therapy in the mixed infection group were 61.4% and 70.5%, respectively, both higher than those in the Gram-positive infection group (28.4% and 35.3%) and the Gram-negative infection group (32.4% and 30.9%). The rates of internal fixation removal in the three groups were 15.5%, 17.6%, and 22.7%, respectively, with no significant difference among the groups (χ 2=1.147, P=0.564). The infection recurrence rates at 1 month after infection control were 6.9%, 7.4%, and 9.1%, respectively, with no significant difference among the groups (χ 2=0.224, P=0.894). The infection recurrence rates at 3 months after infection control were 8.6%, 8.8%, and 13.6%, respectively, with no significant difference among the groups (χ 2=0.996, P=0.608). The infection recurrence rates at 1 year after infection control were 10.3%, 11.8%, and 27.3%, respectively, with a significant difference among the groups (χ 2=7.990, P=0.018). The proportions of patients with severe disability at 1 year postoperatively were 10.3%, 8.8%, and 25.0%, respectively, with a significant difference among the groups (χ 2=10.078, P=0.039). The mixed infection group had higher 1-year infection recurrence rate and proportion of severe disability than the other two groups. Conclusions:Surgical site infection after lumbar fusion is mainly caused by Gram-positive bacteria. Patients with mixed infection have a higher detection rate of methicillin-resistant Staphylococcus aureus and are associated with more debridements, longer intravenous antibiotic therapy, higher 1-year infection recurrence rate, and poorer functional outcomes. Advanced age, obesity, diabetes mellitus, prolonged operative time, and increased intraoperative blood loss may be associated with mixed infection.