The promiscuous and highly mobile resistome of Acinetobacter baumannii

Abstract

Antimicrobial resistance (AR) is a major global threat to public health. Understanding the population dynamics of AR is critical to restrain and control this issue. However, no study has provided a global picture of the whole resistome of Acinetobacter baumannii , a very important nosocomial pathogen. Here we analyse 1450+ genomes (covering >40 countries and >4 decades) to infer the global population dynamics of the resistome of this species. We show that gene flow and horizontal transfer have driven the dissemination of AR genes in A. baumannii . We found considerable variation in AR gene content across lineages. Although the individual AR gene histories have been affected by recombination, the AR gene content has been shaped by the phylogeny. Furthermore, many AR genes have been transferred to other well-known pathogens, such as Pseudomonas aeruginosa or Klebsiella pneumoniae . Despite using this massive data set, we were not able to sample the whole diversity of AR genes, which suggests that this species has an open resistome. Our results highlight the high mobilization risk of AR genes between important pathogens. On a broader perspective, this study gives a framework for an emerging perspective (resistome-centric) on the genomic epidemiology (and surveillance) of bacterial pathogens.

Genomic Characterization of Mobile Genetic Elements Associated With Carbapenem Resistance of Acinetobacter baumannii From India

“…The A. baumannii isolates in this study belonged to diverse sequence types (STs) representing four International clones, ICs (IC1/CC1, IC2/CC2, IC7/CC25, and IC8/CC10), one clonal complex, i.e., CC862, and one singleton ( Table 2 ). Although genes that confer resistance to different antimicrobials were identified across all clonal lineages, the majority of the genes that encode for aminoglycoside modifying enzymes, RMTases, macrolide resistance, sulfonamide resistance, chloramphenicol, and rifampicin resistance were confined to isolates belonging to IC2 ( Rodrigues et al, 2021 ; Hernández-González et al, 2022 ).…”

Zoonotic Acinetobacter baumannii: the need for genomic epidemiology in a One Health context

“… 3 Importantly, a 2022 study has shown that the resistome of A baumannii is highly mobile, showing many cases of horizontal gene transfer with other important human pathogens such as Klebsiella pneumoniae and Pseudomonas aeruginosa . 9 In connection with the previous point, even if the animal clones of A baumannii do not pose a public health risk per se , the antibiotic genes within them can be horizontally transferred to isolates from other human relevant bacterial species, which could be risky.…”

Acinetobacter baumannii Sampled from Cattle and Pigs Represent Novel Clones

“…One isolate from a pig fecal sample (PF33) was discarded as it showed a high percentage of contamination (>60%). For the phylogenetic analysis, we also included 148 human-related A. baumannii genomes previously genotyped in Hernández-González et al ( 15 ). These genomes were chosen as they are part of the eight main international clones (ICs).…”