β-Lactamase Diversity in Clinical Bacterial Isolates

β-Lactamases represent a broad family of enzymes that undermine the efficacy of β-lactam antibiotics by hydrolysing the characteristic β-lactam ring. Their diversity arises from multiple evolutionary lineages (classes A–D) and from the mobilisation of resistance genes via plasmids and transposons. Extended‐spectrum β-lactamases (ESBLs), notably CTX‐M, SHV and TEM variants, have become widespread in Enterobacterales, while AmpC cephalosporinases (e.g. CMY and DHA families) contribute additional resistance to cephamycins and some third‐generation cephalosporins. Chromosomal ampC genes may be upregulated by promoter mutations or insertion elements, and plasmid‐encoded ampC genes facilitate horizontal transfer across species. Carbapenemases further extend resistance to last‐resort agents, posing a global health challenge. Clinical isolates of Escherichia coli, Klebsiella pneumoniae and Enterobacter spp. exhibit dynamic assemblages of β-lactamase genes, often combining ESBLs, AmpC and carbapenemases on complex plasmid backbones. Surveillance studies integrating whole‐genome sequencing, plasmid typing and standardised susceptibility testing are key to mapping transmission networks, guiding empiric therapy and informing stewardship strategies on a global scale.

Research from Nature Portfolio

Recent studies have applied nationwide genomic surveillance to thousands of Enterobacterales isolates resistant to third‐generation cephalosporins and carbapenems. Whole‐genome sequencing combined with standardised susceptibility testing has resolved the complete spectrum of blaCTX‐M, blaCMY and blaDHA variants across Escherichia coli and Klebsiella pneumoniae populations. Long‐read assemblies of resistance plasmids have revealed the replicon types and geographical distribution of carbapenemase‐encoding elements, as well as cases of cryptic carbapenemase carriage undetected by routine phenotypic assays. These integrative approaches are providing a scalable blueprint for harmonised molecular monitoring of β‐lactamase emergence and dissemination.

β-Lactamase Diversity in Clinical Bacterial Isolates publication trend

The graph below shows the total number of articles in β-lactamase diversity in clinical bacterial isolates across all publications each year (not limited to Nature Index journals).

Technical terms

β-lactamase: Enzyme that hydrolyses the β-lactam ring of antibiotics, conferring resistance to penicillins and cephalosporins.

Extended‐spectrum β-lactamase (ESBL): Class of β-lactamases capable of hydrolysing third‐generation cephalosporins and monobactams but inhibited by clavulanic acid.

AmpC β-lactamase: Cephalosporinase often produced chromosomally or via plasmids, conferring resistance to cephamycins and some extended‐spectrum cephalosporins.

Plasmid‐mediated resistance: Antibiotic resistance genes carried on mobile genetic elements (plasmids) that can transfer between bacteria.

Chromosomal AmpC: AmpC gene located on the bacterial chromosome, whose expression may be upregulated by promoter mutations.

References

1. National genomic surveillance integrating standardized quantitative susceptibility testing clarifies antimicrobial resistance in Enterobacterales. Nature Communications (2023).
2. Community Emergence of Cefixime-Resistant Escherichia coli Belonging to ST12 with Chromosomal AmpC Hyperproduction. Antibiotics (2024).
3. Molecular epidemiology of β-lactamases in ceftriaxone-resistant Enterobacterales bloodstream infections in the mid-Atlantic United States. Antimicrobial Agents and Chemotherapy (2025).
4. High prevalence of multidrug-resistant Enterobacterales carrying extended-spectrum beta-lactamase and AmpC genes isolated from neonatal sepsis in Ahvaz, Iran. BMC Microbiology (2024).