Sodium ((2S,3R)-3-methyloxiran-2-yl)phosphonate, commonly known as fosfomycin sodium, is a broad-spectrum antibiotic. It is the sodium salt of fosfomycin, a small molecule characterized by a unique phosphonic acid epoxide structure. This salt form enhances its water solubility, making it suitable for parenteral administration, particularly intravenous infusion. Fosfomycin sodium is primarily used as an active pharmaceutical ingredient (API) in the treatment of serious systemic infections caused by susceptible bacteria, including multidrug-resistant strains. Its mechanism of action involves the irreversible inhibition of the enzyme MurA (UDP-N-acetylglucosamine enolpyruvyl transferase), which is essential for the first committed step in bacterial cell wall biosynthesis. This bactericidal action makes it effective against both Gram-positive and Gram-negative pathogens. It is a critical agent in the clinical arsenal, especially for combating complicated urinary tract infections (cUTIs) and infections where other antibiotics have failed. Due to its distinct mechanism and low cross-resistance, it is often reserved for targeted therapy. As a biologically active compound, it also serves as a key reference standard and tool in microbiological and biochemical research related to antibiotic resistance and cell wall synthesis pathways.