Exploring the clinical outcomes and molecular characteristics of Acinetobacter baumannii bloodstream infections: a study of sequence types, capsular types, and drug resistance in China.
Jiao Chen, Yanting Shao, Zhibin Cheng, Guanghui Li, Fen Wan, Chenyan Gao, Danqin Wu, Dandan Wei, Yang Liu, Rong Li
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引用次数: 0
Abstract
Background: Bloodstream infections (BSIs) caused by Acinetobacter baumannii have been associated with high mortality. To improve the outcomes of patients, this study explored the clinical characteristics and outcomes of patients with BSIs, as well as the phenotypic and genomic characteristics of these isolates.
Methods: A retrospective cohort study was conducted involving A. baumannii BSIs cases from 2020 to 2023 in a tertiary hospital. The clinical characteristics of all A. baumannii isolates were evaluated. Virulence phenotypes of all isolates were evaluated using the growth curve, biofilm-forming assay, antiserum complement killing, and G.mellonella killing assay. Furthermore, whole-genome sequencing (WGS) was utilized to analyze genomic characteristics.
Results: The 30-day mortality rate of 67 patients with BSIs was 55.22%. Patients in the death group had significantly lower platelet counts and higher CRP levels than those in the survival group. Additionally, higher rates of antibiotic use (≥2 classes) and greater carbapenem exposure were observed. Among the isolates, CRAb accounted for 80.6%, ST2 accounted for 76.12%, and KL2/3/7/77/160 accounted for 65.67%. The predominant KL type was KL3, found in 19.4% of the isolates. All ST2 and KL2/3/7/77/160 isolates were CRAb. Among the isolates, 90.7% of the CRAb isolates coharbored blaOXA-23 and blaOXA-66 , while one coharbored blaNDM-1 and blaOXA-23 . Compared with non-ST2 and non KL2/3/7/77/160 infections, ST2 and KL2/3/7/77/160 infections had higher mortality rates (66.0% vs. 23.5%, P=0.002; 65.90% vs. 34.78%, P=0.015). Patients with ST2 and KL2/3/7/77/160 infections underwent more invasive procedures, received two or more antibiotics and carbapenem therapy before isolation, and had lower serum albumin levels. These isolates exhibited significantly higher resistance to antimicrobial agents. No significant differences in virulence phenotypes were observed between the two groups, except for biofilm formation between the ST2 and non-ST2 groups (P=0.002). However, these isolates harbored more virulence genes related to iron uptake and biofilm formation.
Conclusion: The mortality rate associated with BSIs caused by A. baumannii is high. It is of great significance for clinicians to pay attention to the risk factors of the clinical characteristics of patients and to identify the ST and KL types of the strains causing the infection at an early stage.
背景：鲍曼不动杆菌引起的血流感染（bsi）与高死亡率相关。为了改善患者的转归，本研究探讨了bsi患者的临床特征和转归，以及这些分离株的表型和基因组特征。方法：对某三级医院2020 - 2023年鲍曼不动杆菌BSIs病例进行回顾性队列研究。评估所有鲍曼不动杆菌分离株的临床特征。采用生长曲线法、生物膜形成法、抗血清补体杀伤法和mellonella杀伤法评价分离株的毒力表型。此外，利用全基因组测序（WGS）分析基因组特征。结果：67例bsi患者30天死亡率为55.22%。死亡组患者血小板计数明显低于生存组，CRP水平明显高于生存组。此外，观察到较高的抗生素使用率（≥2类）和更多的碳青霉烯暴露。其中，螃蟹占80.6%，ST2占76.12%，KL2/3/7/77/160占65.67%。KL型以KL3型为主，占19.4%。ST2和KL2/3/7/77/160株均为CRAb。其中90.7%的螃蟹分离株携带blaOXA-23和blaOXA-66, 1株携带blaNDM-1和blaOXA-23。与非ST2和非KL2/3/7/77/160感染相比，ST2和KL2/3/7/77/160感染的死亡率更高(66.0% vs. 23.5%， P=0.002；65.90% vs. 34.78%， P=0.015)。ST2和KL2/3/7/77/160感染的患者在分离前接受了两种或两种以上的抗生素和碳青霉烯类药物治疗，并且血清白蛋白水平较低。这些分离株对抗菌药物表现出明显更高的耐药性。除ST2组和非ST2组之间有生物膜形成外，两组间毒力表型无显著差异（P=0.002）。然而，这些分离物含有更多与铁摄取和生物膜形成相关的毒力基因。结论：鲍曼不动杆菌致脑损伤死亡率高。重视患者临床特征的危险因素，早期识别引起感染的菌株ST型和KL型，对临床医生具有重要意义。
期刊介绍：
Frontiers in Cellular and Infection Microbiology is a leading specialty journal, publishing rigorously peer-reviewed research across all pathogenic microorganisms and their interaction with their hosts. Chief Editor Yousef Abu Kwaik, University of Louisville is supported by an outstanding Editorial Board of international experts. This multidisciplinary open-access journal is at the forefront of disseminating and communicating scientific knowledge and impactful discoveries to researchers, academics, clinicians and the public worldwide.
Frontiers in Cellular and Infection Microbiology includes research on bacteria, fungi, parasites, viruses, endosymbionts, prions and all microbial pathogens as well as the microbiota and its effect on health and disease in various hosts. The research approaches include molecular microbiology, cellular microbiology, gene regulation, proteomics, signal transduction, pathogenic evolution, genomics, structural biology, and virulence factors as well as model hosts. Areas of research to counteract infectious agents by the host include the host innate and adaptive immune responses as well as metabolic restrictions to various pathogenic microorganisms, vaccine design and development against various pathogenic microorganisms, and the mechanisms of antibiotic resistance and its countermeasures.
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