Fusidic Acid Sodium

751-94-0

C31H47O6Na

538.69

White to off-white powder

Source: Fusidium coccineum
Water Content (Karl Fischer): ≤2.0%

2-8°C

Spectrum: Fusidic Acid is a narrow-spectrum agent that that is bacteriostatic against Gram-positive bacteria but is primarily used against such as S. aureus and coagulate-negative species. It is also active against Gram-positive anaerobes but does not have activity against Gram-positive aerobes.

Microbiology Applications: Fusidic Acid Sodium is commonly used in clinical in vitro microbiological antimicrobial susceptibility tests (panels, discs, and MIC strips) against Gram-positive microbial isolates. Medical microbiologists use AST results to recommend antibiotic treatment options. Representative MIC values include:
Methicillin-resistant Staphylococcus aureus (MRSA) 0.12 µg/mL - 1.0 µg/mL
Streptococcus epidermidis 0.25 µg/mL

Fusidic Acid resistance has emerged and given rise to methicillin-resistant Staphylocccus aureus (MRSA) and methicillin-susceptible S. aureus. Key resistance determinants include fusA gene mutations, encoding for elongation factor G, and plasmid-mediated resistance (ie. acquisition of resistance gene fusB).

Susceptibility testing in vitro is affected by the presence of blood or serum due to the high protein binding of Fusidic Acid. There is also a modest inoculum effect.

Eukaryotic Cell Culture Applications: Fusidic Acid suppresses nitric oxide toxicity in pancreatic islet cells. It may protect islet beta cells from destruction in type 1 (insulin-dependent) diabetes mellitus. Fusidic Acid dose-dependently inhibited lysis of isolated islet cells by activated macrophages, a process mediated by nitric oxide. No protection was observed when cells were exposed to oxygen radicals or the alkylating beta cell toxin streptozotocin. The suppression of nitric oxide was not due to the compound's inhibition of protein biosynthessis thus it represents a yet unknown activity for this compound.