Carbapenem Resistance Characterization in Acinetobacter Species

Acinetobacter species, particularly Acinetobacter baumannii, have emerged as critical nosocomial pathogens owing to their remarkable capacity to acquire and disseminate resistance to carbapenem antibiotics. Carbapenems, once considered agents of last resort against multidrug‐resistant Gram-negative infections, are rendered ineffective by a suite of bacterial mechanisms including the production of carbapenem‐hydrolysing β-lactamases, alterations in outer‐membrane permeability, efflux pump overexpression and acquisition of mobile genetic elements. Key carbapenemases belong to Ambler class D (OXA‐type enzymes) and class B metallo‐β-lactamases (e.g. NDM-type), often encoded by blaOXA or blaNDM genes embedded in transposons and plasmids. Insertion sequences such as ISAba1 may upregulate adjacent β-lactamase genes, amplifying resistance levels. Whole‐genome sequencing and high‐resolution typing have revealed the global spread of a handful of high‐risk international clones, which harbour diverse combinations of OXA‐23, OXA-24/40, OXA-58 and NDM carbapenemases. Understanding the interplay between genetic context, clonal lineage and phenotypic resistance is essential to inform surveillance, guide antimicrobial stewardship and develop novel therapeutic strategies against these formidable pathogens.

Research from Nature Portfolio

A comprehensive survey of clinical samples in the Southwest Amazon region mapped the biodiversity and molecular epidemiology of carbapenem‐resistant bacteria, among which A. baumannii featured prominently. Seventy-two species carrying class A, B and D carbapenemase genes were identified, with A. baumannii isolates routinely harbouring blaOXA-23-like, blaOXA-24-like or blaNDM-like genes. Retrospective analysis of laboratory data from 2018–2021 showed diverse genetic contexts, including plasmid-borne and chromosomal carbapenemase determinants. These findings underscored regional reservoirs of resistance and provided critical data for state surveillance programmes, highlighting the need for coordinated public‐health responses to curb dissemination.

Carbapenem Resistance Characterization in Acinetobacter Species publication trend

The graph below shows the total number of articles in carbapenem resistance characterization in acinetobacter species across all publications each year (not limited to Nature Index journals).

Technical terms

Carbapenemase: A β-lactamase enzyme capable of hydrolysing carbapenem antibiotics, undermining their therapeutic efficacy.

OXA-type enzyme: A class D β-lactamase commonly found in Acinetobacter that confers resistance to carbapenems through hydrolysis.

bla gene: A gene encoding a β-lactamase enzyme; nomenclature (e.g. blaOXA-23) indicates enzyme family and variant.

Insertion sequence (IS): A small mobile genetic element that can activate or mobilise adjacent resistance genes when located upstream.

International clone (IC): A globally disseminated A. baumannii lineage defined by multilocus sequence typing and associated with multidrug resistance.

References

1. Biodiversity of carbapenem-resistant bacteria in clinical samples from the Southwest Amazon region (Rondônia/Brazil). Scientific Reports (2024).
2. Co-Existence of blaNDM-1, blaOXA-23, blaOXA-64, blaPER-7 and blaADC-57 in a Clinical Isolate of Acinetobacter baumannii from Alexandria, Egypt. International Journal of Molecular Sciences (2023).
3. Prevalence of Carbapenem Resistance Genes among Acinetobacter baumannii Isolated from a Teaching Hospital in Taiwan. Antibiotics (2023).
4. Genomic study of Acinetobacter baumannii strains co-harboring blaOXA-58 and blaNDM-1 reveals a large multidrug-resistant plasmid encoding these carbapenemases in Brazil. Frontiers in Microbiology (2024).