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[In vitro activity of fusidic acid in combination with various antibiotics against Staphylococcus epidermidis]
Abstract:
In vitro antibacterial activity of fusidic acid (FUC) in combination with cefotaxime (CTX), imipenem (IMP), gentamicin (GEN), amikacin (AKN), rifampin (RIF), fosfomycin (FOS), vancomycin, pefloxacin (PEF) was studied against 19 presumably pathogen meti-R Staphylococcus epidermidis strains. The study was carried out by means of a microtiter checkerboard method (FICs index, 19 strains) and killing-curves (3 strains). FUC x GEN, FUC x AKN and FUC x IMP combinations were found synergistic with achievable therapeutic concentrations for IMP (MIC in the combination less than 1 microgram/ml) but with higher concentrations for AKN and GEN (greater than or equal to 8 micrograms/ml). FUC x PEF combinations were regularly antagonistic. FUC x RIF, and FUC x FOS combinations showed a modal FIC greater than or equal to 4 but were found respectively additive and synergistic with killing-curve method. Remaining FUC combinations results were variable. FUC resistant mutant frequency, studied for 3 S. epidermidis strains, was similar as S. aureus one's (0.5.10(-7) a 2.5.10(-8)).
Insights
Fusidic acid combinations show varied effectiveness against Staphylococcus epidermidis. Synergistic effects were observed with imipenem, amikacin, and gentamicin, but antagonism occurred with pefloxacin.
Area of Science:
- Microbiology
- Pharmacology
Context:
- Staphylococcus epidermidis is a significant pathogen, particularly in healthcare settings.
- Methicillin-resistant (meti-R) strains pose a therapeutic challenge.
- Fusidic acid is an antibiotic used to treat bacterial infections.
Purpose:
- To evaluate the in vitro antibacterial activity of fusidic acid in combination with other antibiotics against meti-R Staphylococcus epidermidis.
- To determine synergistic, additive, or antagonistic effects of these combinations.
Summary:
- Combinations of fusidic acid with gentamicin, amikacin, and imipenem demonstrated synergistic activity against meti-R Staphylococcus epidermidis.
- Fusidic acid and pefloxacin showed antagonistic effects, while fusidic acid with rifampin was additive and with fosfomycin synergistic based on killing-curve methods.
- The study utilized microtiter checkerboard and killing-curve assays to assess combination efficacy.
Impact:
- Identifies potentially effective antibiotic combinations for treating meti-R Staphylococcus epidermidis infections.
- Provides data on drug interactions that can inform clinical treatment strategies.
- Understanding these interactions is crucial for combating antibiotic resistance.