Antimicrobial Resistance in Citrobacter Species
Summary
Citrobacter species are Gram-negative members of the Enterobacterales that have emerged as opportunistic pathogens in both community and healthcare settings. They are intrinsically capable of harbouring AmpC β-lactamases and frequently acquire extended-spectrum β-lactamases (ESBLs) and carbapenemases, including KPC, NDM and OXA variants. Resistance genes are often located on conjugative plasmids, integrons and transposons, facilitating horizontal dissemination among Citrobacter and other Enterobacterales. Clinical isolates display diverse multidrug-resistant profiles against cephalosporins, carbapenems, fluoroquinolones and aminoglycosides. Food, environmental and animal reservoirs contribute to global spread, complicating empirical therapy and underscoring the need for robust surveillance, stewardship and novel therapeutic strategies.
Research from Nature Portfolio
Recent studies have delineated genetic requirements for Citrobacter during bloodstream infection, identifying metabolic pathways for glucose, mannitol and cysteine utilisation as critical fitness factors in murine models. The Tat secretion system and its substrate SufI were shown to contribute substantially to in vivo survival. A separate investigation revealed a Citrobacter freundii strain harbouring both NDM-1 and KPC-2 on distinct plasmids, demonstrating interspecies transfer of carbapenemase genes. The coexistence of diverse β-lactamases on mobile elements underscores the emergence of high-risk clones with enhanced resistance and the potential for rapid dissemination.
Antimicrobial Resistance in Citrobacter Species publication trend
The graph below shows the total number of articles in antimicrobial resistance in citrobacter species across all publications each year (not limited to Nature Index journals).
Technical terms
β-lactamase: Enzyme that hydrolyses β-lactam antibiotics, conferring resistance.
Carbapenemase: β-lactamase subclass capable of degrading carbapenem antibiotics.
Plasmid: Extrachromosomal DNA molecule capable of horizontal transfer between bacteria.
Integron: Genetic element that captures and expresses gene cassettes, often antibiotic resistance genes.
Transposon: Mobile DNA sequence that can move within and between genomes, facilitating gene dissemination.
Horizontal gene transfer: Movement of genetic material between organisms outside of vertical inheritance, accelerating spread of resistance.
Multidrug resistance: Resistance to three or more classes of antimicrobial agents in a single strain.
References
- Citrobacter freundii fitness during bloodstream infection. Scientific Reports (2018).
- Citrobacter freundii carrying blaKPC-2 and blaNDM-1: characterization by whole genome sequencing. Scientific Reports (2016).
- Antibiotic Resistance Hotspot: Comparative Genomics Reveals Multiple Strains of Multidrug-Resistant Citrobacter portucalensis in Edible Snails. International Journal of Molecular Sciences (2024).
- Coexistence of blaIMP-4, blaNDM-1 and blaOXA-1 in blaKPC-2-producing Citrobacter freundii of clinical origin in China. Frontiers in Microbiology (2023).
- Comparative Genomic Analyses of Virulence and Antimicrobial Resistance in Citrobacter werkmanii, an Emerging Opportunistic Pathogen. Microorganisms (2023).
About these summaries
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