Evaluation of the antibacterial activity of Akkermansia muciniphila extract against Enterococcus faecium isolates.

BACKGROUND: The emergence of multidrug-resistant Enterococcus faecium, particularly vancomycin-resistant strains (VRE), poses a significant global health threat and necessitates novel therapeutic strategies. Akkermansia muciniphila, a beneficial gut commensal, is a promising next-generation probiotic with antimicrobial properties. This study aimed to evaluate the antibacterial and antivirulence efficacy of A. muciniphila extract against clinical E. faecium isolates. METHODS: Sixty urine and fecal samples were collected from the Iraqi Hospital (October 2024 to February 2025). Fifteen clinical E. faecium isolates were confirmed by VITEK and 16 S rRNA sequencing. The presence of ace (adhesion) and esp (biofilm) virulence genes was determined using PCR. The antimicrobial activity of commercial A. muciniphila extract was assessed using agar well diffusion and broth microdilution to determine the Minimum Inhibitory Concentration (MIC). The effect of the extract on ace and esp gene expression was quantified by quantitative real-time PCR (qRT-PCR). RESULTS: Ace and esp were detected in all 15 and esp in 13 strains, respectively. The A. muciniphila extract demonstrated significant growth inhibition, with an MIC of 6.25 mg/mL. Sub-inhibitory concentrations of the extract resulted in a significant downregulation of virulence gene expression, with ace expression reduced by up to 7.14-fold and esp expression reduced by up to 250-fold compared to the untreated controls (P < 0.05). CONCLUSIONS: A. muciniphila extract inhibited the growth of E. faecium and reduced the expression of virulence genes (ace/esp), suggesting potential therapeutic efficacy against drug-resistant infections. However, additional mechanistic studies and in vivo confirmation are required for clinical applications.