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The effect of protamine on antibiotic action against Staphylococcus epidermidis biofilms
G K Richards1, J Prentis, R F Gagnon
1Department of Microbiology, Montreal General Hospital, McGill University, Quebec, Canada.
Abstract:
Infection associated with medical devices may involve bacterial biofilms, a possible cause of antibiotic resistance. Protamine, a basic polypeptide, depresses the metabolic activity of Staphylococcus epidermidis in a standardized biofilm assay. The resistance of the biofilm preparations to many antibiotics, with the sole exception of rifampin, was confirmed. Rifampin produced predominant lysis and killing with foci of genetically programmed resistance. The combination of protamine with antibiotics produced no change, except the combination with rifampin where clear classic synergism with a totally bactericidal outcome was demonstrated. Protamine is a member of the larger family of charged polycations, some of which possess membrane potential altering properties, possibly interfering with the protective nature exhibited by the negatively charged bacterial biofilm matrix.
Insights
Protamine reduces Staphylococcus epidermidis biofilm metabolic activity and enhances antibiotic effectiveness. Combining protamine with rifampin demonstrated significant synergistic bacterial killing, offering new strategies against device-associated infections.
Area of Science:
- Microbiology
- Biotechnology
- Infectious Diseases
Background:
- Bacterial biofilms on medical devices are a significant cause of persistent infections and antibiotic resistance.
- Staphylococcus epidermidis is a common pathogen in device-associated infections, forming robust biofilms.
- Existing antibiotics often show limited efficacy against mature bacterial biofilms.
Purpose of the Study:
- To investigate the effect of protamine on Staphylococcus epidermidis biofilms.
- To evaluate the efficacy of protamine in combination with antibiotics against these biofilms.
- To explore the potential of protamine as an anti-biofilm agent.
Main Methods:
- Standardized biofilm assay was used to culture Staphylococcus epidermidis biofilms.
- Metabolic activity of biofilms was measured in the presence of protamine.
- Biofilm resistance to various antibiotics was tested, with a focus on rifampin.
- Synergistic effects of protamine combined with antibiotics were assessed.
Main Results:
- Protamine significantly depressed the metabolic activity of Staphylococcus epidermidis biofilms.
- Biofilms exhibited resistance to most tested antibiotics, except for rifampin.
- Rifampin alone caused lysis and killing, with some resistant foci.
- The combination of protamine and rifampin demonstrated clear synergism, resulting in complete bacterial killing.
Conclusions:
- Protamine effectively reduces the metabolic activity of Staphylococcus epidermidis biofilms.
- Protamine, in combination with rifampin, exhibits potent synergistic bactericidal activity.
- Protamine's polycationic nature may interfere with biofilm matrix properties, enhancing antibiotic efficacy.
- This combination therapy holds promise for combating medical device-associated infections.