Neospiramycin I

Neospiramycin I is a macrolide antibiotic and a derivative of Spiramycin I. Neospiramycin I is effective against the macrolide-sensitive KB210 strain of S. aureus, but ineffective against the macrolide-resistant KB224 strain, with minimum inhibitory concentrations (MIC) of 3.12 and greater than 100 µg/mL, respectively; it is also effective against B. cereus, B. subtilis, M. luteus, E. coli, and K. pneumoniae, with respective MIC values of 1.56, 3.12, 3.12, 0.2, 50, and 12.5 µg/mL. Neospiramycin I binds to the ribosomes of E. coli, with an inhibitory concentration 50 (IC50) of 1.2 µM. It protects mice from death in a type III S. pneumoniae infection model, with an effective dose 50 (ED50) of 399.8 mg/kg[1][2].