Anaerobic bacteria in the human intestinal microbiota play a pivotal role in antibiotic resistance, primarily through the production of β-lactamases. This narrative review explores the diversity of β-lactamases found in intestinal anaerobes, their functional characteristics, and clinical implications. Species of the genus Bacteroides are major producers, harboring enzymes from Ambler classes A (e.g. CepA, CfxA and CblA), B (e.g. CfiA and CcrA) and D (e.g. OXA-347), with activity ranging from cephalosporinases to carbapenemases and oxacillinases. Other gut members, including Clostridioides difficile, Fusobacterium nucleatum, and Acidaminococcus fermentans, also encode specific β-lactamases. These enzymes contribute to microbiota resilience following β-lactam exposure and can protect neighboring bacteria via extracellular degradation. This protective mechanism has inspired therapeutic applications, such as recombinant β-lactamases (ribaxamase, SYN-006) designed to preserve gut integrity during antibiotic therapy. Understanding these intrinsic resistance mechanisms is essential for optimizing antibiotic stewardship and mitigating the spread of resistance genes.
Dutkiewicz et al. (Fri,) studied this question.