Antimicrobial Efficacy of Melissa officinalis Extract Against Pathogenic Bacterial Isolates: Inhibition of Biofilm Formation and Adhesion

Document Type : Research Paper

Authors

1 College of Dentistry, Kufa University, Najaf, Iraq

2 Department of Basic and Medical Science, Babylon University, Pharmacy College, Al-Mustaqbal University, Iraq

3 Department of Microbiology, Hammurabi College of Medicine, University of Babylon, Babylon, Iraq

4 College of Pharmacy, Al-Mustaqbal University, Hillah, Iraq

5 Department of Basic and Medical Science, College of Nursing, University of Babylon, Iraq

Abstract

Melissa officinalis, commonly known as lemon balm, is recognized for its broad-spectrum antimicrobial properties against various pathogenic bacteria, suggesting potential therapeutic benefits for treating infectious diseases.  This study aimed to investigate the inhibitory effects of M. officinalis extract on human pathogenic bacteria and to assess its ability to prevent bacterial biofilm formation and adhesion. The antibacterial activity of the aqueous extract of M. officinalis was evaluated using disc-diffusion and agar-well diffusion methods. The antimicrobial efficacy of the extract was compared with that of standard antibiotics. Additionally, tests for adherence and biofilm formation were conducted. The M. officinalis extract demonstrated inhibitory zones ranging from 25 to 35 mm against all tested microorganisms. While some bacterial isolates were susceptible to imipenem, the majority exhibited resistance. Notably, certain isolated bacteria displayed strong adhesion and biofilm formation in response to the extract, whereas most Gram-negative bacteria showed moderate adherence and biofilm activity. The findings indicate that M. officinalis extracts are highly effective against a range of clinical isolates, including those associated with urinary tract infections. This suggests that these extracts may offer a more effective alternative to conventional antibiotics, particularly in combating bacterial adhesion and biofilm development.

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