Abstract
BackgroundIn May 2015, we noticed an increase in carbapenem-resistant Acinetobacter baumannii (CRAB) infections in the Medical Intensive Care Unit (MICU). To investigate this, we studied the extent of environmental contamination and subsequent onward clonal transmission of CRAB.MethodsWe conducted a one-day point prevalence screening (PPS) of the patients and environment in the MICU. We screened patients using endotracheal tube aspirates and swabs from nares, axillae, groin, rectum, wounds, and exit sites of drains. We collected environmental samples from patients’ rooms and environment outside the patients’ rooms. CRAB isolates from the PPS and clinical samples over the subsequent one month were studied for genetic relatedness by whole genome sequencing (WGS).ResultsWe collected 34 samples from seven patients and 244 samples from the environment. On the day of PPS, we identified 8 CRAB carriers: 3 who screened positive and 5 previously known clinical infections. We detected environmental contamination in nearly two-thirds of the rooms housing patients with CRAB. WGS demonstrated genetic clustering of isolates within rooms but not across rooms. We analysed 4 CRAB isolates from clinical samples following the PPS. One genetically-related CRAB was identified in the respiratory sample of a patient with nosocomial pneumonia, who was admitted to the MICU five days after the PPS.ConclusionThe extensive environmental colonization of CRAB by patients highlights the importance of environmental hygiene. The transmission dynamics of CRAB needs further investigation.
Highlights
In May 2015, we noticed an increase in carbapenem-resistant Acinetobacter baumannii (CRAB) infections in the Medical Intensive Care Unit (MICU)
Another study investigating an outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit (ICU) demonstrated that majority of the clinical isolates were identical, the additional use of whole genome sequencing (WGS) demonstrated that some of the isolates were not related to the outbreak strain despite having the same susceptibility pattern [8]
There were fifteen patients in the MICU on the day of screening, with three unoccupied rooms. (Figure 2) Five patients were not swabbed as they were known to have CRAB, while another three were excluded from screening as they had been admitted to the MICU for less than 24 h
Summary
In May 2015, we noticed an increase in carbapenem-resistant Acinetobacter baumannii (CRAB) infections in the Medical Intensive Care Unit (MICU). Another study investigating an outbreak of Pseudomonas aeruginosa in a neonatal ICU demonstrated that majority of the clinical isolates were identical, the additional use of whole genome sequencing (WGS) demonstrated that some of the isolates were not related to the outbreak strain despite having the same susceptibility pattern [8]. These studies highlight the limitation of using the phenotypic method in defining relatedness of isolates
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