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Risk and Prognostic Factors for Bloodstream Infections Due to Clonally Transmitted Acinetobacter baumannii ST2 with
Jingru Ji1, Wei Chen2, Peitao Jiang3
1Department of Infectious Disease, Nanjing Drum Tower Hospital, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, Jiangsu Province, People's Republic of China.
Background:
Multidrug-resistant Acinetobacter baumannii (MDR-AB) is a major cause of bacterial bloodstream infections (BSIs), associated with high morbidity and mortality. The risk and prognostic factors for BSIs caused by clonally transmitted A. baumannii ST2, carrying armA, blaOXA-23 and blaOXA-66, remain unclear.
Methods:
We retrospectively analyzed 97 hospitalized patients with A. baumannii BSI (January 2019-May 2022). Whole-genome sequencing and bioinformatic analysis characterized the strains. Clinical data were reviewed to identify risk factors for secondary BSIs, A. baumannii BSIs with mixed infections involving extra-bloodstream pathogens, and mortality predictors.
Results:
High-risk clone sequence type (ST) 2 was identified in 87 isolates (89.7%), with 86 exhibiting clonal dissemination. Carbapenems and aminoglycosides resistance occurred in 78.4% of strains, linked to armA, blaOXA-23, and blaOXA-66. Patients' median age was 56.6 years (range: 11-93), with males comprising 62.9%. Elderly patients (>65 years) accounted for 40.2%, 85.6% had hospital stays >10 days, and 84.5% had ICU admissions. Adverse outcomes were observed in 55.7% of cases. ICU admission (OR = 5.144, 95% CI: 1.290-20.511, P = 0.020) and open injury (OR = 5.998, 95% CI: 1.164-30.892, P = 0.032) were specific risk factors significantly associated with BSIs, while the presence of three or more underlying diseases (OR = 6.419, 95% CI: 2.074-19.866, P = 0.001) was significantly associated with increased mortality risk.
Conclusion:
The majority of A. baumannii strains causing BSIs in this study belonged to multidrug-resistant ST2 lineage, harboring armA, blaOXA-23 and blaOXA-66. Risk factors for secondary and mixed infections included prolonged ICU stays, mechanical ventilation (≥7 days), and open injuries, while poor prognosis was linked to severe comorbidities and extended invasive ventilation. Targeted infection control strategies are critical to reducing mechanical ventilation duration and managing open injuries in high-risk patients.
Insights
Multidrug-resistant Acinetobacter baumannii ST2 infections are common and linked to high mortality. ICU admission and open injuries increase BSI risk, while comorbidities predict poor outcomes.
Area of Science:
- Infectious Diseases
- Clinical Microbiology
- Genomics
Background:
- Multidrug-resistant Acinetobacter baumannii (MDR-AB) is a significant cause of hospital-acquired infections.
- Acinetobacter baumannii ST2 is a high-risk clone associated with carbapenem and aminoglycoside resistance.
- Understanding risk and prognostic factors for MDR-AB bloodstream infections (BSIs) is crucial.
Purpose of the Study:
- To identify risk factors for secondary and mixed Acinetobacter baumannii BSIs.
- To determine predictors of mortality in patients with Acinetobacter baumannii BSIs.
- To characterize the genetic and clinical features of Acinetobacter baumannii ST2 BSIs.
Main Methods:
- Retrospective analysis of 97 hospitalized patients with Acinetobacter baumannii BSI.
- Whole-genome sequencing and bioinformatic analysis of bacterial isolates.
- Clinical data review to identify risk and prognostic factors.
Main Results:
- Acinetobacter baumannii ST2 was identified in 89.7% of isolates, with widespread clonal dissemination.
- Resistance to carbapenems and aminoglycosides was prevalent, linked to specific resistance genes.
- ICU admission and open injuries were significant risk factors for BSIs; multiple comorbidities predicted mortality.
Conclusions:
- MDR-AB BSIs are frequently caused by the ST2 clone carrying specific resistance genes.
- Prolonged ICU stays, mechanical ventilation, and open injuries are key risk factors for secondary/mixed infections.
- Effective infection control strategies targeting ventilation and wound management are essential.
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