Neospiramycin I is a macrolide antibiotic and derivative of spiramycin I.¹It is active against the macrolide-sensitive KB210, but not the macrolide-resistant KB224, strain ofS. aureus(MICs = 3.12 and >100 µg/ml, respectively), as well asB. cereus,B. subtilis,M. luteus,E. coli, andK. pneumoniae(MICs = 1.56, 3.12, 3.12, 0.2, 50, and 12.5 µg/ml, respectively). Neospiramycin I binds toE. coliribosomes with an IC₅₀value of 1.2 µM. It protects against mortality in a mouse model ofS. pneumoniaetype III infection (ED₅₀= 399.8 mg/kg).²

1.Sano, H., Inoue, M., and ?mura, S.Chemical modification of spiramycins. II. Synthesis and antimicrobial activity of 4’-deoxy derivatives of neospiramycin I and their 12-(Z)-isomersJ. Antibiot. (Tokyo)37(7)738-749(1984) 2.Sano, H., Inoue, M., Yamashita, K., et al.Chemical modification of spiramycins. I. Synthesis of the acetal derivatives of neospiramycin IJ. Antibiot. (Tokyo)36(10)1336-1344(1983)