| DOI: 10.29090/psa.2025.03.25.3835 | Pharm Sci Asia 2025; 52(3), 376-384 |
Effect of combination of sub-inhibitory concentrations of cefepime and Thymus vulgaris essential oil in modulating biofilm formation of Enterococcus faecalis in vitroHwazen Amer Shnyoor and Ayaid Khadem Zgair
- Department of Biology, College of Science, University of Baghdad, Baghdad, Iraq, 10071
Modifying the biofilm-forming ability of Enterococcus faecalis may offer a valuable approach to treating infections. This study evaluated the effects of sub-minimum inhibitory concentrations (sub-MICs) of cefepime and Thymus vulgaris essential oil, alone and in combination, on the biofilm formation of E. faecalis isolated from urine samples of patients with urinary tract infections (UTIs). Minimum inhibitory concentrations (MICs) of both agents were determined, and their sub-MICs were tested using a polystyrene microtiter plate assay. Real-time PCR was used to assess the effect of cefepime sub-MICs on esp gene expression. The checkerboard assay was employed to evaluate the combined effect of both agents on biofilm inhibition. The incidence of UTI infection with E. faecalis was 13.15% of UTI cases. No significant correlation was observed between cefepime susceptibility and biofilm formation (r = –0.28, P = 0.42), whereas a significant positive correlation was found with T. vulgaris essential oil (r = +0.66, P < 0.05). Sub-MICs of cefepime (½, ¼, ⅛, and 1⁄16 MIC) and T. vulgaris essential oil (½ and ¼MIC) significantly reduced biofilm formation (P < 0.05). Additionally, cefepime sub-MICs significantly downregulated esp gene expression (P < 0.05). The combination of both agents at sub-MICs showed greater inhibition of biofilm formation than either agent alone. These findings suggest that cefepime and T. vulgaris essential oil, particularly in combination at sub-MIC levels, may be an effective strategy to control E. faecalis biofilm-associated infections.
Keyword:
Adhesion; Biofilm; Cefepime; Enterococcus faecalis; Sub-inhibitory MICs.
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