Molecular Epidemiology of Carbapenem-Resistant Acinetobacter baumannii

Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as a leading cause of intractable hospital‐acquired infections worldwide, driven by its remarkable ability to withstand last-line β-lactam antibiotics. Molecular epidemiology combines genome sequencing, typing schemes and resistance gene analysis to reveal how CRAB lineages evolve, disseminate and persist in diverse healthcare environments. Key mechanisms include production of OXA-type and metallo-β-lactamases, often mobilised by insertion sequences or plasmids, and modifications of outer-membrane proteins. International clones, designated IC1–IC9, dominate global CRAB populations and exhibit distinct resistome profiles shaped by local antibiotic use and patient movement. Whole-genome sequencing (WGS) has revolutionised outbreak investigations by delineating transmission pathways within wards, detecting environmental reservoirs and uncovering horizontal gene transfer events. Multilocus sequence typing (MLST) and core-genome MLST provide standardised frameworks for inter-laboratory surveillance, while resistome and virulome analyses inform therapeutic strategies. Environmental contamination of intensive care units (ICUs), colonisation of medical devices and within-host diversification underscore the challenge of eradication. Regional studies reveal that endemic CRAB populations may differ substantially from clonal outbreaks in high-income settings, necessitating tailored infection control and antimicrobial stewardship. The integration of molecular data with epidemiological metadata underpins proactive monitoring, rapid outbreak containment and the development of novel diagnostics and therapeutics.

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Molecular Epidemiology of Carbapenem-Resistant Acinetobacter baumannii publication trend

The graph below shows the total number of articles in molecular epidemiology of carbapenem-resistant acinetobacter baumannii across all publications each year (not limited to Nature Index journals).

Technical terms

Carbapenemase: Enzyme that hydrolyses carbapenem antibiotics, conferring high-level resistance.

Whole-genome sequencing (WGS): Determination of the complete DNA sequence of an organism’s genome, used to track pathogen transmission and evolution.

Multilocus sequence typing (MLST): Method for characterising bacterial isolates by sequencing fragments of housekeeping genes to assign sequence types.

Global clone: A widely dispersed lineage of A. baumannii defined by shared sequence type and resistance profile.

Resistome: The collection of all antibiotic resistance genes present in a bacterial population.

Horizontal gene transfer (HGT): Movement of genetic material between organisms, enabling rapid acquisition of resistance determinants.

References

1. Endemicity and diversification of carbapenem-resistant Acinetobacter baumannii in an intensive care unit. The Lancet Regional Health - Western Pacific (2023).
2. A global view on carbapenem-resistant Acinetobacter baumannii. mBio (2023).
3. Molecular characterization of multidrug resistant Acinetobacter baumannii clinical isolates from Alexandria, Egypt. Frontiers in Cellular and Infection Microbiology (2023).
4. International Clones of High Risk of Acinetobacter Baumannii—Definitions, History, Properties and Perspectives. Microorganisms (2023).
5. Development and evaluation of a core genome multilocus typing scheme for whole-genome sequence-based typing of Acinetobacter baumannii. PLOS ONE (2017).