Secondary bacterial infections of Carbapenem-Resistant Acinetobacter baumannii in patients with COVID-19 admitted to Chinese ICUs.

Abstract

Background: A significant proportion of patients who are hospitalized with coronavirus disease 2019 (COVID-19), particularly those being admitted to ICUs, exhibit the development of secondary bacterial infections (SBIs). However, there is a lack of detailed epidemiological investigations and genetic information of Carbapenem-Resistant Acinetobacter baumannii (CRAB) based on whole genome sequencing (WGS), which is one of the frequently detected bacteria among COVID-19 patients, to confirm alterations in the clonal structure and infection mechanism.

Results: A total of 37 unique CRAB strains, sourced from patients, along with an additional 2 CRAB strains form the environment, were isolated. Among the cohort of 37 patients, 22 individuals succumbed to CRAB infection, resulting in a mortality rate of 54.46%. The median duration of illness for these patients was 7.95 days, highlighting the severity and rapid progression of CRAB infections in this patient population. A total of 22 CRAB strains, isolated from deceased individuals, in addition to two strains isolated from the environment, were subjected to further investigation. All 24 CRAB isolates exhibited a high ability to form biofilm and displayed a similar spectrum of resistance. Except for two isolates from patients with COVID-19, all the remaining CRAB isolates were categorized as ST195 and demonstrated highly close genetic background based on analysis of WGS. The ST195 strain of CRAB harbored three copies of the bla_OXA-23 gene located on the chromosome, each of which was carried by Tn2006. Notably, one Tn2006 element was integrated within Tn6022, leading to the formation of AbaR4-like resistance islands Tn6166-I.

Conclusions: Our findings underscore the significance of SBIs in the COVID-19 pandemic, particularly those caused by CRAB and specifically those belonging to MLST types that were previously prevalent in ICUs.