Carbapenem-resistant Acinetobacter baumannii (CRAB) was brought to the ICU in Hangzhou on multiple occasions as patients were admitted, creating a large "reservoir" of the bacteria that contaminated beds and equipment.
Summary
Background
Carbapenem-resistant Acinetobacter baumannii (CRAB) is a major global public health problem. Often studied in the context of hospital outbreaks, little is known about the persistence and evolutionary dynamics of endemic Acinetobacter baumannii (CRAB) populations.
Methods
A three-month cross-sectional observational study was conducted in a 28-bed intensive care unit (ICU) in Hangzhou, China. A total of 5068 samples were collected from the hospital environment (n = 3985), patients (n = 964), and staff (n = 119). Acinetobacter baumannii (CRAB) isolates were obtained from 10.5% of these samples (n = 532). All of these isolates, plus an additional 19 from clinical infections, were characterized by whole genome sequencing.
Results
The ICU CRAB population was dominated by OXA-23-producing global clone 2 isolates (99.3% of all isolates) that could be divided into 20 distinct groups, defined through genome sequencing. CRAB was persistently present in the ICU, driven by the regular introduction of distinct groups.
The hospital environment was highly contaminated, with CRAB isolated from bed units on 183/335 (54.6%) sampling occasions, but from patients on only 72/299 (24.1%) sampling occasions. CRAB was extended to bed units and adjacent rooms, and following relocation of patients within the ICU. We also observed three horizontal gene transfer events between CRAB strains in the UCI, involving three different plasmids.
Interpretation
The epidemiology of Acinetobacter baumannii (CRAB) in this setting contrasted with previously described clonal outbreaks in high-income countries, highlighting the importance of environmental CRAB reservoirs in the epidemiology of ICU and the unique challenges in containing the spread of CRAB in ICUs where this important multidrug-resistant pathogen is endemic.
Comments
Of 35 CRAB-positive patients in the study, 14 acquired CRAB during their ICU stay. Samples of drug-resistant bacteria were found more frequently in bed unit settings (54.6%) than in patients (24.1%), with ventilators (27.9%) and dispensing carts (25.6%). %) with higher probability of Acinetobacter baumannii (CRAB) yield samples.
Publishing their findings today (date to be confirmed) in The Lancet Regional Health - Western Pacific, the international group of researchers led by the University of Birmingham is calling for urgent action to help prevent hospitals from becoming infected with the bacteria.
Study co-author Professor Alan McNally, from the University of Birmingham, commented: "Acinetobacter baumannii (CRAB) represents a serious risk to hospitalized patients and can cause serious illness, including pneumonia, urinary tract infection, bacteraemia, meningitis and soft tissue infections, all of which can be very difficult to treat due to the multidrug resistance of the bacteria.
“The number of CRAB found in this ICU highlights the urgent need for targeted infection prevention and control measures in healthcare facilities where such large accumulations of the bacteria are likely to occur, so that we can stop the global spread of this pathogen".
The study highlights the important role of the environment in the persistence of CRAB and eventual acquisition by patients. Researchers call for bacteria buildup to be addressed with infection prevention and control measures, including:
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The researchers sampled the entire ICU, including staff, patients and the environment, to reveal a remarkable diversity of CRABs in this environment: they were introduced into the unit when patients were admitted and caused the bacteria to spread within the unit. ICU.
Acinetobacter baumannii (CRAB) can persist for prolonged periods on hospital surfaces and medical equipment, and colonize patients within 48 hours of admission, facilitated by hospital staff, shared equipment, flow of air and plumbing. CRAB outbreaks may require interventions or infrastructure changes that impose clinical, logistical, and financial burdens.
Antibiotic-resistant infections are a major threat to global public health. CRAB infections are found worldwide with severely limited treatment options, prompting the World Health Organization to designate CRAB as a priority organism for which new therapies are urgently required.
Professor McNally added: “In the absence of new therapeutic agents, effective CRAB IPC strategies are vital, if we are to limit the morbidity and mortality caused by the bacteria in hospitals. “We must develop a deep understanding of the persistence, transmission and evolution of CRAB populations in such environments.”
Added value of this study
We conducted a comprehensive genome-wide observational study of the prevalence and movement of CRAB in an ICU in a high prevalence setting. By using intensive sampling of the ICU environment and monitoring patients, we show the extent of CRAB colonization, contamination, and transmission within the ICU. Our data also show how frequently CRAB is introduced into the ICU and how quickly CRAB populations adapt to the ICU environment and share mobile genetic elements through horizontal gene transfer.
Implications of all available evidence
The high prevalence, multiclonal nature, and high degree of genome plasticity of CRAB in this ICU highlight the urgent need for targeted infection prevention and control measures in high prevalence settings to stop the global spread of this multidrug-resistant nosocomial pathogen.
