Investigation of an outbreak of carbapenem resistant Acinetobacter baumannii in an intensive care unit during the COVID-19 epidemic

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BackgroundDuring the Coronavirus Disease 2019 (COVID-19) epidemic, the strain on intensive care units (ICUs) has increased, which made them more vulnerable to the threat of multidrug-resistant organism (MDRO).AimThis study aims to investigate an outbreak of carbapenem resistant Acinetobacter baumannii (CRAB) infection in a general adult ICU of a tertiary hospital in China during the COVID-19 epidemic and evaluate the effectiveness of intervention measures.MethodsDemographic and clinical data of 37 patients were collected, and 230 environmental samples were collected. Whole genome sequencing (WGS) analysis was performed on clinical and environmental isolates. An evolutionary tree was constructed based on the WGS data. The infection control team implemented a bundle of MDRO interventions, including a termination of COVID-19 infection control measures and implementation of ‘three-step’ cleaning and disinfection method.FindingsThere were 37 patients found to have CRAB infection or colonization in the ICU from December 2022 to April 2023, of whom 35 were hospital-acquired. 12 CRAB isolates were obtained from the environment and medical equipment. Through WGS analysis, the CRAB strains from the medical environment and bronchoscopes were found to be highly homologous to those from patients’ clinical specimens. This demonstrated that the infection outbreak was caused by the lack of MDRO prevention and control measures. Following intervention, the CRAB detection rate gradually declined, with no positive samples for CRAB found in the ICU environment or on bronchoscopes.ConclusionThe infection control measures for COVID-19 conflicted with basic MDRO prevention and control strategies, likely contributing to the outbreak. Therefore, established infection prevention and control measures should be consistently followed, as they represent the most effective approach to preventing MDRO.