Fosfomycin in antimicrobial stewardship programs

Due to the increase in antimicrobial resistance, strategies such as antimicrobial stewardship programs (ASP) have been developed to improve the clinical results, decrease the adverse effects and the development of resistances and ensure cost-effective therapies. Fosfomycin has a unique mechanism of action against Gram-positive and Gram-negative bacteria. Cross-resistance is uncommon; however, fosfomycin should be used in combination in severe infections to avoid selecting resistant mutations. Fosfomycin's oral formulation facilitates sequential treatment, has low toxicity and high tissue penetration, even in the central nervous system and bone. Fosfomycin is active against resistant Gram-positive bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin- resistant enterococci and penicillin-resistant Streptococcus pneumoniae, as well as against resistant Gram-negative bacteria such as extended-spectrum beta-lactamase-producing and carbapenemase-producing enterobacteria. Fosfomycin is therefore useful for cases of persistent bacteremia, skin and soft tissue infections, as a glycopeptide-sparing and carbapenem-sparing drug for healthcare-associated infections and for polymicrobial infections. Published studies have demonstrated the synergy between fosfomycin and beta-lactams, daptomycin and glycopeptides against MSSA and MRSA; with linezolid in biofilm-associated infections and with aminoglycosides and colistin against Gram-negative bacteria, providing a nephroprotective effect.