Mapping the Thematic Structure and Evolution of AmpC β-Lactamase Research: A Bibliometric Analysis

Background: AmpC β-lactamases are complex resistance determinants due to inducible chromosomal expression, stable derepression, plasmid-mediated dissemination, potential for co-resistance, and diagnostic interpretation challenges. Nevertheless, the scientific production, citation structure, and thematic evolution of the AmpC β-lactamase literature have not been comprehensively mapped. This study aimed to evaluate this literature using bibliometric methods. Methods: Original articles and reviews indexed in SCI-E and ESCI within the Web of Science Core Collection were evaluated when “AmpC” appeared in the title field. After an additional microbiological filter, 1183 documents published between 1980 and 2026 were included. Analyses were performed using R, bibliometrix, and Biblioshiny. Results: Scientific production increased from the 2000s onward. Antimicrobial Agents and Chemotherapy and Journal of Antimicrobial Chemotherapy were among the most productive and most locally cited sources, while the United States ranked first in publication output and total citation impact. The most frequent keywords were Escherichia coli, ESBL, Klebsiella pneumoniae, and Enterobacterales. Conceptual analyses showed that the literature was structured around chromosomal AmpC biology, plasmid-mediated dissemination, resistance ecology intersecting with ESBLs, a cluster interpretable as a One Health axis, and clinical management themes. Trend topic analysis showed that multidrug resistance, carbapenemase, and virulence have become more visible in recent years. Conclusions: AmpC β-lactamase literature has broadened from an earlier emphasis on chromosomal resistance biology toward a multidimensional research field encompassing plasmid-mediated dissemination, resistance ecology, One Health-related themes, and clinical management. The recent prominence of concepts related to multidrug resistance phenotypes, the concurrent dissemination of resistance determinants, and pathogen virulence may suggest that the field is increasingly being addressed within a broader antimicrobial resistance context.