Antimicrobial Resistance Mechanisms in Gram-Negative Bacteria

Gram-negative bacteria employ a multifaceted arsenal to evade antimicrobial agents, posing a growing threat to human health worldwide. The intrinsic barrier presented by their dual-membrane envelope limits antibiotic entry, while active efflux systems expel a wide range of compounds. Enzymatic degradation—chiefly via β-lactamases and carbapenemases—neutralises critical classes of antibiotics, and alterations to target sites further reduce drug affinity. Acquisition of resistance determinants through horizontal gene transfer, often mediated by plasmids and integrons, accelerates dissemination of multidrug resistance across species and geographies. Biofilm formation on surfaces and medical devices enhances persistence and tolerance, complicating both treatment and eradication. Surveillance of genetic lineages, understanding the interplay between ecological reservoirs and clinical infections, and the rational design of novel agents or adjuvants remain essential to counteract these adaptable pathogens.

Research from Nature Portfolio

Recent deep sequencing of Escherichia coli from community and outpatient settings in Punjab, Pakistan, has mapped over 5 000 genomes, revealing a distinct distribution of resistance determinants compared with high-income regions. The study demonstrated that local antibiotic use drives selection of globally circulating multidrug-resistant lineages and underscored the need for longitudinal, multi-regional genomic surveillance to grasp the ecology–evolution nexus in resistance maintenance and spread. In neonatal care, a foundational investigation into sepsis in low- and middle-income countries characterised the genomic diversity of Enterobacterales isolates, identifying multiple cephalosporin and carbapenem resistance genes on mobile elements. This work highlighted intraspecies diversity of Klebsiella pneumoniae and Escherichia coli lineages responsible for severe infections and emphasised the urgency of tailored treatment protocols for vulnerable populations.

Antimicrobial Resistance Mechanisms in Gram-Negative Bacteria publication trend

The graph below shows the total number of articles in antimicrobial resistance mechanisms in gram-negative bacteria across all publications each year (not limited to Nature Index journals).

Technical terms

β-Lactamase: Enzyme that hydrolyses the β-lactam ring of penicillins and cephalosporins, neutralising their antibacterial activity.

Carbapenemase: A subclass of β-lactamases capable of degrading carbapenem antibiotics, often associated with mobile genetic elements.

Porin: Protein channel in the outer membrane that permits passive diffusion of small molecules, including some antibiotics.

Efflux pump: Active transporter that expels toxic compounds, including antibiotics, from the bacterial cell.

Plasmid: Extrachromosomal DNA molecule that can carry resistance genes and transfer them between bacteria.

Extended-spectrum β-lactamase (ESBL): Enzyme variant that hydrolyses third-generation cephalosporins and aztreonam, often inhibited by clavulanic acid.

References

1. Deep sequencing of Escherichia coli exposes colonisation diversity and impact of antibiotics in Punjab, Pakistan. Nature Communications (2024).
2. Characterization of antimicrobial-resistant Gram-negative bacteria that cause neonatal sepsis in seven low- and middle-income countries. Nature Microbiology (2021).
3. Longitudinal analysis within one hospital in sub-Saharan Africa over 20 years reveals repeated replacements of dominant clones of Klebsiella pneumoniae and stresses the importance to include temporal patterns for vaccine design considerations. Genome Medicine (2024).
4. The Gram-negative permeability barrier: tipping the balance of the in and the out. mBio (2023).