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. 2025 Dec;16(1):2542489.
doi: 10.1080/21505594.2025.2542489. Epub 2025 Aug 24.

Virulence factors are preserved within carbapenem-resistant Acinetobacter baumannii clades

Mor N Lurie-Weinberger  1 , Adi Cohen  1 , Hadas Kon  1 , Ophir Kastel  1 , Alona Keren-Paz  1 , David Schwartz  1 , Jonathan Lellouche  1   2 , Amir Nutman  1   3 , Sammy Frenk  1 , Vered Schechner  1   3 , Elizabeth Temkin  1 , Lena E Friberg  4 , George L Daikos  5   6 , Anna Skiada  5   6 , Emanuele Durante-Mangoni  7   8 , Dafna Yahav  3   9 , Leonard Leibovici  3   10 , Yaakov Dickstein  1   11 , Yael Dishon Benattar  11   12 , Mical Paul  11   13 , Yehuda Carmeli  1   3 ; AIDA Study Group
Affiliations

Virulence factors are preserved within carbapenem-resistant Acinetobacter baumannii clades

Mor N Lurie-Weinberger et al. Virulence. 2025 Dec.

Abstract

Carbapenem-resistant Acinetobacter baumannii (CRAB) is an important threat to hospitalized patients. The virulence of A. baumannii varies between strains and geographic locations, which is believed to be related to its genetic plasticity. A comprehensive evaluation of virulence factor (VF) content of CRAB across genetically related clones is lacking. Therefore, we aimed to determine the evolution of VFs among 246 CRAB isolates belonging to major STs, ST2 and ST3. We used WGS to assess 136 VFs and found that 110 VFs were present in most isolates (49 VFs were universally present, 61 were ubiquitous) and 25 occurred sporadically. The distribution of the 25 sporadic VF genes was homogenous in ST3 but heterogeneous in ST2. Within ST2, we found high intra-clade homogeneity and high inter-clade heterogeneity of VFs. The homogeneity of VF content in ST2 clades and its uniformity in ST3 suggest a distant evolutionary segregation of VFs at the root of ST/clade divergence. VF content reflects remote events resulting in minimal variation between isolates belonging to the same ST/clade. Thus, the alleged differences in virulence of CRAB strains between geographical locations reflect differences in clonal distribution.

Keywords: Acinetobacter baumannii; antibiotic resistance; carbapenem resistance; evolution; virulence factors.

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Conflict of interest statement

Yehuda Carmeli received consultancy fees from MSD, Qpex, Pfizer, Roche, and Enlivex and payment for lectures from Pfizer. Emanuele Durante‐Mangoni received grants from Pfizer, Shionogi, Advanz Pharma, Infectopharm, and Angelini, and payment for lectures from Pfizer, Shionogi, Advanz Pharma, Infectopharm, Angelini, Abbvie, and Trx and participated on a data safety monitoring board or advisory board of Roche, Genentech, and Pfizer. George Daikos received honoraria for lectures from Pfizer, MSD and received support to attend meetings from Pfizer and participated on an advisory board of Vitaris, MSD, and Pfizer. Dafna Yahav received grants from Pfizer and Shionogi. All other authors declared no competing interests in this work.

Figures

Figure 1.
Figure 1.
Virulence factors by sequence type (ST) and clades. A. Boxplot of number of VFs in ST2 and ST3 isolates. B. Boxplot of number of VFs in ST2 clades. Dots indicate outliers.
Figure 2.
Figure 2.
Clustered heatmap of sparse virulence factors among ST2 isolates. Blue boxes indicate that the gene is present; white boxes show the gene is absent. The colours on the left indicate clades. Isolates marked as “2” are ST2 with no designated clade.
Figure 3.
Figure 3.
Clustered heatmap of sparse virulence factors among ST3 isolates. Blue boxes indicate that the gene is present; white boxes show the gene is absent.
See this image and copyright information in PMC

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