Abstract：
BACKGROUND: Differentiating Acinetobacter baumannii complex (ABC) infection from colonization remains difficult and further complicated in polymicrobial infections.
OBJECTIVE: To assess the frequency of polymicrobial ABC infections and associated mortality. We hypothesized a lower mortality in polymicrobial infections if ABC isolation reflects colonization in some polymicrobial infections.
METHODS: A systematic review was conducted in PubMed, Scopus and CENTRAL for studies reporting ABC pulmonary and bloodstream infections. The proportion of infections that were polymicrobial and the magnitude of the association between polymicrobial (vs monomicrobial) infection and mortality were estimated with meta-analyses.
RESULTS: Based on 80 studies (9759 infections) from 23 countries, the pooled proportion of polymicrobial infection was 27% (95% CI 22-31%) and was similarly high for bloodstream and pulmonary infections. Polymicrobial infection was variably and insufficiently defined in most (95%) studies. Considerable heterogeneity (I2 = 95%) was observed that persisted in subgroup analyses and meta-regressions. Based on 17 studies (2675 infections), polymicrobial infection was associated with lower 28-day mortality (OR = 0.75, 95% CI 0.58-0.98, I2 = 36%). However, polymicrobial infection was not associated with in-hospital mortality (OR = 0.97, 95% CI 0.69-1.35, I2 = 0%) based on 14 studies (953 infections). The quality of evidence (GRADE) for the association of polymicrobial (vs monomicrobial) infection with mortality was low and at high risk of bias.
CONCLUSIONS: Polymicrobial ABC infections are common and may be associated with lower 28-day mortality. Considering the heterogeneity of polymicrobial infections and limitations of the available literature, more research is required to clarify the clinical impact of polymicrobial (vs monomicrobial) ABC infection.
OBJECTIVE: To assess the frequency of polymicrobial ABC infections and associated mortality. We hypothesized a lower mortality in polymicrobial infections if ABC isolation reflects colonization in some polymicrobial infections.
METHODS: A systematic review was conducted in PubMed, Scopus and CENTRAL for studies reporting ABC pulmonary and bloodstream infections. The proportion of infections that were polymicrobial and the magnitude of the association between polymicrobial (vs monomicrobial) infection and mortality were estimated with meta-analyses.
RESULTS: Based on 80 studies (9759 infections) from 23 countries, the pooled proportion of polymicrobial infection was 27% (95% CI 22-31%) and was similarly high for bloodstream and pulmonary infections. Polymicrobial infection was variably and insufficiently defined in most (95%) studies. Considerable heterogeneity (I2 = 95%) was observed that persisted in subgroup analyses and meta-regressions. Based on 17 studies (2675 infections), polymicrobial infection was associated with lower 28-day mortality (OR = 0.75, 95% CI 0.58-0.98, I2 = 36%). However, polymicrobial infection was not associated with in-hospital mortality (OR = 0.97, 95% CI 0.69-1.35, I2 = 0%) based on 14 studies (953 infections). The quality of evidence (GRADE) for the association of polymicrobial (vs monomicrobial) infection with mortality was low and at high risk of bias.
CONCLUSIONS: Polymicrobial ABC infections are common and may be associated with lower 28-day mortality. Considering the heterogeneity of polymicrobial infections and limitations of the available literature, more research is required to clarify the clinical impact of polymicrobial (vs monomicrobial) ABC infection.
摘要：
背景：区分鲍曼不动杆菌复合体（ABC）感染与定植仍然很困难，并且在多微生物感染中进一步复杂化。
目的：评估多重微生物ABC感染的频率和相关死亡率。我们假设如果ABC分离反映了某些多微生物感染中的定植，则多微生物感染的死亡率较低。
方法：在PubMed，Scopus和CENTRAL用于报告ABC肺部和血流感染的研究。通过荟萃分析估计了多微生物感染的比例以及多微生物（与单抗微生物）感染与死亡率之间的关联程度。
结果：基于来自23个国家的80项研究（9759例感染），多重微生物感染的合并比例为27%(95%CI22-31%),血流和肺部感染的合并比例同样高.在大多数（95％）研究中，多微生物感染的定义可变且不充分。观察到相当大的异质性（I2=95％），在亚组分析和荟萃回归中仍然存在。根据17项研究（2675例感染），多微生物感染与较低的28日死亡率相关(OR=0.75,95%CI0.58~0.98,I2=36%).然而,根据14项研究(953例感染),多重微生物感染与院内死亡率无关(OR=0.97,95%CI0.69~1.35,I2=0%).多微生物（与单抗微生物药物）感染与死亡率相关的证据质量（GRADE）较低，偏倚风险较高。
结论：多微生物ABC感染是常见的，可能与较低的28天死亡率有关。考虑到微生物感染的异质性和现有文献的局限性，需要更多的研究来阐明多重微生物(vs单抗微生物)ABC感染的临床影响.
目的：评估多重微生物ABC感染的频率和相关死亡率。我们假设如果ABC分离反映了某些多微生物感染中的定植，则多微生物感染的死亡率较低。
方法：在PubMed，Scopus和CENTRAL用于报告ABC肺部和血流感染的研究。通过荟萃分析估计了多微生物感染的比例以及多微生物（与单抗微生物）感染与死亡率之间的关联程度。
结果：基于来自23个国家的80项研究（9759例感染），多重微生物感染的合并比例为27%(95%CI22-31%),血流和肺部感染的合并比例同样高.在大多数（95％）研究中，多微生物感染的定义可变且不充分。观察到相当大的异质性（I2=95％），在亚组分析和荟萃回归中仍然存在。根据17项研究（2675例感染），多微生物感染与较低的28日死亡率相关(OR=0.75,95%CI0.58~0.98,I2=36%).然而,根据14项研究(953例感染),多重微生物感染与院内死亡率无关(OR=0.97,95%CI0.69~1.35,I2=0%).多微生物（与单抗微生物药物）感染与死亡率相关的证据质量（GRADE）较低，偏倚风险较高。
结论：多微生物ABC感染是常见的，可能与较低的28天死亡率有关。考虑到微生物感染的异质性和现有文献的局限性，需要更多的研究来阐明多重微生物(vs单抗微生物)ABC感染的临床影响.
