Mechanisms of antibiotic resistance in enterococci Original paper
Researched by:
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Divine Aleru
ID
Divine Aleru
Read MoreI am a biochemist with a deep curiosity for the human microbiome and how it shapes human health, and I enjoy making microbiome science more accessible through research and writing. With 2 years experience in microbiome research, I have curated microbiome studies, analyzed microbial signatures, and now focus on interventions as a Microbiome Signatures and Interventions Research Coordinator.
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Microbes
Microbes
Microbes are microscopic organisms living in and on the human body, shaping health through digestion, vitamin production, and immune protection. When microbial balance is disrupted, disease can occur. This guide explains key microbe types—bacteria, viruses, fungi, protozoa, and archaea—plus major pathogenic and beneficial examples.
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Divine Aleru
Read More
Researched by:
-
Divine Aleru
ID
Divine Aleru
Read More
Microbiome Signatures identifies and validates condition-specific microbiome shifts and interventions to accelerate clinical translation. Our multidisciplinary team supports clinicians, researchers, and innovators in turning microbiome science into actionable medicine.
Divine Aleru
What was reviewed?
This review examined the molecular mechanisms that allow Enterococcus faecalis and Enterococcus faecium to develop antibiotic resistance and persist in the gut microbiome and hospital environment. The authors reviewed genetic, biochemical, and microbiological evidence explaining how Enterococcus modifies drug targets, alters cell wall structure, activates stress response pathways, and acquires resistance genes. These mechanisms allow Enterococcus to survive antibiotic exposure, expand within the gut microbiome, and transition into multidrug-resistant pathogens.
Who was reviewed?
The review evaluated microbiome and clinical strains of Enterococcus faecalis and Enterococcus faecium, including multidrug-resistant isolates from hospitalized patients. These strains originated from the gastrointestinal microbiome, bloodstream, and infection sites. The review examined Enterococcus populations that developed resistance through genetic mutation, horizontal gene transfer, and environmental selection within microbiome and clinical settings.
What were the most important findings?
Enterococcus developed resistance through genetic plasticity, allowing survival, microbiome dominance, and infection persistence. Major microbial associations included increased abundance of multidrug-resistant Enterococcus in the gut microbiome following antibiotic exposure. Enterococcus acquired resistance genes through mobile genetic elements and modified antibiotic targets such as penicillin-binding proteins and ribosomal RNA. Vancomycin resistance occurred through replacement of D-Ala-D-Ala with D-Ala-D-Lac in the cell wall, reducing antibiotic binding by up to 1000-fold. Enterococcus also activated stress response pathways and altered membrane phospholipid composition to resist daptomycin. Efflux pumps, enzymatic drug inactivation, and target modification further increased resistance. Antibiotic exposure enabled Enterococcus to expand in the microbiome, outcompete other microbes, and disseminate systemically, making Enterococcus a reservoir of antibiotic resistance genes transferable to other pathogens.
What are the greatest implications of this review?
This review showed that Enterococcus expansion represents a microbiome signature of antibiotic exposure and infection risk. Genetic adaptation enables microbiome dominance, resistance development, and systemic infection. Enterococcus functions as a reservoir of resistance genes and contributes to antimicrobial resistance spread, making microbiome monitoring and targeted therapy critical for infection prevention.
Enterococcus faecalis
Enterococcus faecalis is a gut‑adapted, Gram‑positive, non‑spore‑forming facultative anaerobe that becomes an important opportunistic pathogen in healthcare when host barriers are breached or antibiotics select for enterococcal overgrowth. Its clinical impact is driven more by persistence, adhesion, and biofilm biology, quorum‑regulated secreted effectors (fsr‑controlled gelatinase GelE), and high genome plasticity than by a broad repertoire of classical tissue‑destroying toxins. Antimicrobial decision‑making must account for the intrinsic poor activity of cephalosporins, the potential for transferable glycopeptide resistance mediated by van gene clusters, and the need for regimen selection in endocarditis that respects synergy/tolerance and local high‑level aminoglycoside resistance patterns.