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Published on: August 4, 2023
Molecular Characterization of Carbapenem-Resistant Acinetobacter baumannii Isolates Among Intensive Care Unit
Hangbin Hu1, Yifeng Lou1,2, Haiting Feng3
1State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, National Medical Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, People's Republic of China.
Objective:
Critical patients in intensive care unit (ICU) are highly susceptible to acquiring carbapenem-resistant Acinetobacter baumannii (CRAB) infection. To investigate the relationship between nosocomial infections and environmental health, we studied the distribution and homology of CRAB isolates from patients and environment and evaluated the effectiveness of infection control measures.
Methods:
In the 4-month study, we conducted a monthly CRAB screening of the ICU environment prior to disinfection in a Chinese teaching hospital. The ICU underwent routine disinfection procedures twice a day. We collected samples from the environment around the patients before disinfection. Clinical specimens from patients were also screened. The samples obtained were studied for phenotype and homology via antibiotic susceptibility testing, pulsed-field gel electrophoresis (PFGE), and whole-genome sequencing (WGS).
Results:
Ten specimens were sampled from ICU environments. Five were obtained in May 2020, and sputums from patient a in bed A at this time were cultured for CRAB isolates; in June 2020 another 5 environmental specimens were obtained from the same bed unit for CRAB, and sputums from patient b in bed A at this time were also cultured for CRAB isolates. Following intensive infection control measures, environmental sampling was negative in July and August. These 18 CRAB isolates all carried OXA-66 and OXA-23 genes and showed a similar resistance phenotype. WGS showed a close relationship among specimens from patients' sputum and their surroundings, but no homology between patients.
Conclusion:
The analysis of cgMLST and SNPs is more accurate for strain homology analysis. Our data confirm that CRAB isolates spread from patient to environment in ICU; however, contact isolation and disinfection measures are effective in avoiding transmission, highlighting the importance of continued education and surveillance of CRAB. WGS could provide rich information on antimicrobial resistance, which is of great value in scientific research and clinical diagnosis.
Insights
Carbapenem-resistant Acinetobacter baumannii (CRAB) spreads from patients to the ICU environment. Effective infection control measures, including isolation and disinfection, prevent transmission, emphasizing ongoing surveillance.
Area of Science:
- Microbiology
- Infectious Diseases
- Hospital Epidemiology
Background:
- Intensive care units (ICUs) are high-risk environments for healthcare-associated infections.
- Carbapenem-resistant Acinetobacter baumannii (CRAB) poses a significant threat to critically ill patients.
- Understanding the transmission dynamics of CRAB is crucial for effective control.
Purpose of the Study:
- To investigate the distribution and genetic homology of CRAB isolates from patients and the ICU environment.
- To evaluate the effectiveness of implemented infection control measures against CRAB transmission.
- To explore the utility of whole-genome sequencing (WGS) in analyzing CRAB strains.
Main Methods:
- Monthly environmental and clinical specimen sampling in a Chinese teaching hospital ICU over 4 months.
- Phenotypic analysis using antibiotic susceptibility testing.
- Genotypic analysis including pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS).
Main Results:
- CRAB isolates were detected in the ICU environment and from patient sputum samples.
- All 18 CRAB isolates carried OXA-66 and OXA-23 genes with similar resistance profiles.
- WGS revealed close genetic relationships between patient sputum and surrounding environmental isolates, but not between different patients.
Conclusions:
- CRAB isolates can spread from patients to the ICU environment.
- Contact isolation and disinfection are effective in preventing CRAB transmission.
- Whole-genome sequencing provides valuable insights into antimicrobial resistance and strain homology for clinical and research purposes.
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