AUTHOR=Chiang Tsung-Ta , Huang Tzu-Wen , Sun Jun-Ren , Kuo Shu-Chen , Cheng Aristine , Liu Chang-Pan , Liu Yuag-Meng , Yang Ya-Sung , Chen Te-Li , Lee Yi-Tzu , Wang Yung-Chih 

TITLE=Biofilm formation is not an independent risk factor for mortality in patients with Acinetobacter baumannii bacteremia

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=Volume 12 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2022.964539

DOI=10.3389/fcimb.2022.964539

ISSN=2235-2988

ABSTRACT=In the past decades, due to the high prevalence of its antibiotic-resistant isolates, Acinetobacter baumannii has emerged as one of the most troublesome pathogens threatening the global healthcare system. Furthermore, this pathogen has the ability to form biofilms, which is another effective mechanism by which it survives in the presence of antibiotics. However, the clinical impact of biofilm-forming A. baumannii isolates on patients with bacteremia is largely unknown. 
This retrospective study was conducted at five medical centers in Taiwan over a 9-year period. A total of 252 and 459 patients with bacteremia caused by biofilm- and non-biofilm-forming isolates of A. baumannii, respectively, were enrolled. The clinical demographics, antimicrobial susceptibility, biofilm-forming ability, and patient clinical outcomes were analyzed. The biofilm-forming ability of the isolates was assessed using a microtiter plate assay. Multivariate analysis revealed that the higher APACHE II score, shock status, lack of appropriate antimicrobial therapy, and carbapenem resistance of the infected strain were independent risk factors for a 28-day mortality in the patients with A. baumannii bacteremia. However, there was no significant difference between the 28-day survival and non-survival groups, in terms of the biofilm forming ability. 
Compared to the patients infected with non-biofilm-forming isolates, those infected with biofilm-forming isolates had a lower in-hospital mortality rate. Patients with congestive heart failure, underlying hematological malignancy, or those who were recipients of chemotherapy were more likely to get infected with the biofilm-forming isolates. Multivariate analysis showed that congestive heart failure was an independent risk factor for the infection by biofilm-forming isolates, while those with arterial lines tended to get infected with non-biofilm-forming isolates. There were no significant differences in the sources of infection between the biofilm-forming and non-biofilm-forming isolates. Carbapenem susceptibility was also similar between both the groups. 
In conclusion, the patients infected with the biofilm-forming isolates of the A. baumannii exhibited different clinical features than those infected with non-biofilm-forming isolates. The biofilm-forming ability of A. baumannii may also influence the antibiotic susceptibility of its isolates. However, it was not an independent risk factor for a 28-day mortality in the patients with bacteremia.