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Published on: August 4, 2023
Investigation of Peppermint (Mentha piperita) Extract on the Inhibition of Biofilm Formation by Acinetobacter
Zahra Majidi Fard1, Negin Irani Mavi2, Shokoofeh Akbari1
1Department of Biology, Faculty of Convergent Sciences and Technologies, Islamic Azad University, Tehran, Iran.
Background:
Acinetobacter baumannii is a hospital-acquired opportunistic pathogen, with biofilm formation playing a crucial role in its multidrug resistance. Given the rise in antibiotic resistance, herbal medicines, including peppermint (Mentha piperita), have gained attention for their potential antibacterial properties.
Objectives:
This study aimed to evaluate the inhibitory effects of peppermint extract on biofilm formation in A. baumannii strains isolated from clinical samples.
Methods:
A total of 25 A. baumannii strains were isolated from clinical samples at the Faculty of Allied Medical Sciences, Tehran. Their biofilm-forming ability and antibiotic susceptibility against nine antibiotics were assessed using the disk diffusion method. The antibacterial activity of peppermint extract was evaluated by well diffusion, with its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) compared to ciprofloxacin. Synergistic effects between the extract and ciprofloxacin were analyzed, followed by a time-kill assay. Polymerase chain reaction (PCR) was used to detect the presence of PgaA and AbaI genes linked to biofilm formation.
Results:
The study found that 88% of A. baumannii strains exhibited strong biofilm formation. Peppermint extract effectively inhibited biofilm formation, with MIC values ranging from 1.5 to 6 mg/mL (mean MIC: 3.75 ± 1.38 mg/mL) and MBC values equivalent to their respective MIC concentrations. For ciprofloxacin, the MIC for all samples was greater than 2048 mg/mL. No significant synergistic effect was observed between peppermint extract and ciprofloxacin. Both PgaA (involved in biofilm matrix synthesis) and AbaI (quorum sensing-related autoinducer synthase) genes were present in all tested strains.
Conclusions:
Peppermint extract demonstrates biofilm-inhibitory properties against A. baumannii, suggesting its potential as an alternative therapeutic approach for combating biofilm-associated infections.
Insights
Peppermint extract effectively inhibits biofilm formation in multidrug-resistant Acinetobacter baumannii. This suggests its potential as a natural therapeutic agent against hospital-acquired infections.
Area of Science:
- Microbiology
- Pharmacology
- Natural Products
Background:
- Acinetobacter baumannii is a significant hospital-acquired pathogen.
- Biofilm formation by A. baumannii contributes to multidrug resistance.
- Antibiotic resistance necessitates exploration of alternative treatments like herbal medicines.
Purpose of the Study:
- To investigate the efficacy of peppermint (Mentha piperita) extract against A. baumannii.
- To evaluate the extract's impact on biofilm formation in clinical isolates.
- To compare peppermint extract's activity with ciprofloxacin.
Main Methods:
- Isolation and identification of 25 A. baumannii strains from clinical samples.
- Assessment of biofilm formation and antibiotic susceptibility.
- Determination of peppermint extract's antibacterial activity, MIC, and MBC.
- Analysis of synergistic effects with ciprofloxacin and time-kill assays.
- PCR detection of biofilm-related genes (PgaA and AbaI).
Main Results:
- 88% of A. baumannii strains showed strong biofilm formation.
- Peppermint extract inhibited biofilm formation with MICs of 1.5-6 mg/mL and MBCs equal to MICs.
- Ciprofloxacin showed high MICs (>2048 mg/mL) against these strains.
- No significant synergy was observed between peppermint extract and ciprofloxacin.
- All strains possessed PgaA and AbaI genes.
Conclusions:
- Peppermint extract exhibits significant biofilm inhibitory properties against A. baumannii.
- The extract shows potential as a complementary therapeutic agent for biofilm-associated infections.
- Further research into peppermint's mechanism against A. baumannii biofilms is warranted.
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