Influence of severity of infection on the effect of appropriate antimicrobial therapy for Acinetobacter baumannii bacteremic pneumonia

Fang-Yu Kang,Yung-Chih Wang,Te-Li Chen,Yi-Tzu Lee,Aristine Cheng,Shu-Chen Kuo,Ya-Sung Yang,Chorng-Kuang How,Yuag-Meng Liu,Chang-Pan Liu

doi:10.1186/s13756-020-00824-4

Abstract

BackgroundThe impact of appropriate antimicrobial therapy for A. baumannii bacteremic pneumonia has not been well established due to the inclusion of the three phenotypically indistinguishable Acinetobacter species and confounding factors including underlying diseases and severity of infection. This retrospective study aimed to evaluate the impact of appropriate antimicrobial therapy on 14-day mortality in A. baumannii bacteremic pneumonia patients after adjusting for risk factors.MethodsThis study was conducted at five medical centers in Taiwan between July 2012 and June 2016. A. baumannii species identification was performed using reference molecular methods. Risk factors for 14-day mortality were analyzed via logistic regression. The interaction between the Acute Physiology and Chronic Health Evaluation (APACHE) II score and appropriate antimicrobial therapy was assessed using the logistic model.ResultsA total of 336 patients with monomicrobial A. baumannii bacteremic pneumonia were included in this study. The overall 14-day mortality rate was 47.3%. The crude mortality of appropriate antimicrobial therapy was 35.9% (57 of 151 patients). Appropriate antimicrobial therapy was associated with a lower mortality after multivariate adjustment (odds ratio [OR], 0.57; 95% confidence interval [CI], 0.34–0.97; p = 0.04), and the effect was influenced by APACHE II score (OR for interaction term, 0.0098; 95% CI, 0.0005–0.1885; p = 0.002). Further analysis demonstrated that appropriate antimicrobial therapy significantly reduced 14-day mortality among the patients with an APACHE II score > 35 (OR 0.0098; 95% CI 0.0005–0.1885).ConclusionAppropriate antimicrobial therapy decreases 14-day mortality of the most severely ill patients with A. baumannii bacteremic pneumonia.

Highlights

The impact of appropriate antimicrobial therapy for A. baumannii bacteremic pneumonia has not been well established due to the inclusion of the three phenotypically indistinguishable Acinetobacter species and confounding factors including underlying diseases and severity of infection
Appropriate antimicrobial therapy is associated with a lower mortality rate in A. baumannii bacteremia patients [15, 17], and the therapeutic effects might be more significant in severely ill patients [18]
Many factors contribute to the mortality of A. baumannii bacteremic pneumonia, and it remains unclear whether appropriate antimicrobial therapy increases survival among all patients or only among patients with certain demographic or clinical characteristics

Summary

Introduction

The impact of appropriate antimicrobial therapy for A. baumannii bacteremic pneumonia has not been well established due to the inclusion of the three phenotypically indistinguishable Acinetobacter species and confounding factors including underlying diseases and severity of infection. The association between appropriate antimicrobial therapy and mortality for A. baumannii bacteremic pneumonia has been difficult to establish due to the confounding influence of the three phenotypically indistinguishable Acinetobacter species that make up the A. baumannii (Ab) group (A. baumannii, Acinetobacter nosocomialis and Acinetobacter pittii) The aims of this retrospective study were to evaluate the impact of appropriate antimicrobial therapy on the 14-day mortality in genomically identified A. baumannii bacteremic pneumonia patients, and to determine if the therapeutic effect of appropriate antimicrobial therapy differed between patients with different infection severities

Methods

Results

Discussion

Conclusion