Air dispersal of multidrug-resistant Acinetobacter baumannii: implications for nosocomial transmission during the COVID-19 pandemic

AIM: To describe the nosocomial transmission of Air, multidrug-resistant, Acinetobacter baumannii, nosocomial, COVID-19 Acinetobacter baumannii (MRAB) in an open-cubicle neurology ward with low ceiling height, where MRAB isolates collected from air, commonly shared items, non-reachable high-level surfaces and patients were analysed epidemiologically and genetically by whole-genome sequencing. This is the first study to understand the genetic relatedness of air, environmental and clinical isolates of MRAB in the outbreak setting. FINDINGS: Of 11 highly care-dependent patients with 363 MRAB colonization days during COVID-19 pandemic, 10 (90.9%) and nine (81.8%) had cutaneous and gastrointestinal colonization, respectively. Of 160 environmental and air samples, 31 (19.4%) were MRAB-positive. The proportion of MRAB-contaminated commonly shared items was significantly lower in cohort than in non-cohort patient care (0/10, 0% vs 12/18, 66.7%; P<0.001). Air dispersal of MRAB was consistently detected during but not before diaper change in the cohort cubicle by 25-min air sampling (4/4,100% vs 0/4, 0%; P=0.029). The settle plate method revealed MRAB in two samples during diaper change. The proportion of MRAB-contaminated exhaust air grills was significantly higher when the cohort cubicle was occupied by six MRAB patients than when fewer than six patients were cared for in the cubicle (5/9, 55.6% vs 0/18, 0%; P=0.002). The proportion of MRAB-contaminated non-reachable high-level surfaces was also significantly higher when there were three or more MRAB patients in the cohort cubicle (8/31, 25.8% vs 0/24, 0%; P=0.016). Whole-genome sequencing revealed clonality of air, environment, and patients' isolates, suggestive of air dispersal of MRAB. CONCLUSIONS: Our findings support the view that patient cohorting in enclosed cubicles with partitions and a closed door is preferred if single rooms are not available.