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Synergistic Antibacterial Efficacy of Melittin in Combination with Oxacillin against Methicillin-Resistant
Ana Flávia Marques Pereira1, Alessandra Aguirra Sani2, Tatiane Baptista Zapata2
1The Center for the Study of Venoms and Venomous Animals of UNESP (CEVAP), São Paulo State University (UNESP), Botucatu 18619-002, São Paulo, Brazil.
Abstract:
Methicillin-resistant Staphylococcus aureus (MRSA) often cause infections with high mortality rates. Antimicrobial peptides are a source of molecules for developing antimicrobials; one such peptide is melittin, a fraction from the venom of the Apis mellifera bee. This study aimed to evaluate the antibacterial and antibiofilm activities of melittin and its association with oxacillin (mel+oxa) against MRSA isolates, and to investigate the mechanisms of action of the treatments on MRSA. Minimum inhibitory concentrations (MICs) were determined, and synergistic effects of melittin with oxacillin and cephalothin were assessed. Antibiofilm and cytotoxic activities, as well as their impact on the cell membrane, were evaluated for melittin, oxacillin, and mel+oxa. Proteomics evaluated the effects of the treatments on MRSA. Melittin mean MICs for MRSA was 4.7 μg/mL and 12 μg/mL for oxacillin. Mel+oxa exhibited synergistic effects, reducing biofilm formation, and causing leakage of proteins, nucleic acids, potassium, and phosphate ions, indicating action on cell membrane. Melittin and mel+oxa, at MIC values, did not induce hemolysis and apoptosis in HaCaT cells. The treatments resulted in differential expression of proteins associated with protein synthesis and energy metabolism. Mel+oxa demonstrated antibacterial activity against MRSA, suggesting a potential as a candidate for the development of new antibacterial agents against MRSA.
Insights
Melittin combined with oxacillin shows synergistic antibacterial effects against methicillin-resistant Staphylococcus aureus (MRSA). This combination effectively reduces MRSA biofilms and damages bacterial cell membranes, offering potential for new antimicrobial drug development.
Area of Science:
- Microbiology
- Pharmacology
- Biochemistry
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) infections are a significant global health threat due to high mortality rates.
- Antimicrobial peptides, like melittin from bee venom, represent a promising source for novel antimicrobial agents.
- Developing new strategies to combat MRSA is crucial, given increasing antibiotic resistance.
Purpose of the Study:
- To evaluate the antibacterial and antibiofilm efficacy of melittin alone and in combination with oxacillin (mel+oxa) against MRSA.
- To investigate the synergistic effects between melittin and common antibiotics (oxacillin, cephalothin).
- To elucidate the mechanisms of action of melittin and mel+oxa on MRSA, including effects on cell membranes and protein expression.
Main Methods:
- Determination of Minimum Inhibitory Concentrations (MICs) for melittin and oxacillin against MRSA isolates.
- Assessment of synergistic effects using checkerboard assays.
- Evaluation of antibiofilm activity, cytotoxicity (hemolysis, apoptosis), and cell membrane integrity.
- Proteomic analysis to identify treatment-induced changes in MRSA protein expression.
Main Results:
- Melittin exhibited a mean MIC of 4.7 μg/mL against MRSA.
- The combination of melittin and oxacillin (mel+oxa) demonstrated synergistic antibacterial activity and significantly reduced MRSA biofilm formation.
- Mel+oxa treatment induced leakage of cellular components (proteins, nucleic acids, ions) from MRSA, indicating cell membrane damage.
- Proteomic analysis revealed differential expression of proteins involved in protein synthesis and energy metabolism following treatment.
- Melittin and mel+oxa showed no significant cytotoxic effects (hemolysis or apoptosis) on HaCaT cells at their MIC values.
Conclusions:
- The combination of melittin and oxacillin (mel+oxa) exhibits significant antibacterial and antibiofilm activity against MRSA.
- Mel+oxa acts by disrupting the MRSA cell membrane and altering essential cellular processes.
- This synergistic combination presents a promising therapeutic candidate for developing novel agents against challenging MRSA infections.
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