Nosiheptide (Multhiomycin), a thiopeptide antibiotic produced by *Streptomyces actuosus*, is a potent feed additive that promotes animal growth by inhibiting bacterial protein synthesis. It is characterized by an indole side ring system and regiospecific hydroxyl groups on its macrocyclic core.

Nosiheptide demonstrates non-toxic behavior towards mammalian cells at concentrations greater than 100 times the minimum inhibitory concentration (MIC) and retains its effectiveness against Staphylococcus aureus in the presence of 20% human serum. It is particularly potent against Enterococcus spp., the hypervirulent BI strain of Clostridium difficile, and displays remarkable activity against all tested strains of Staphylococcus aureus, including those resistant to multiple drugs (MIC values ≤ 0.25 mg/L). Additionally, Nosiheptide exhibits a significantly extended post-antibiotic effect against both healthcare- and community-associated Staphylococcus aureus when compared to vancomycin. Through time-kill studies, Nosiheptide has been found to quickly eliminate Staphylococcus aureus in a concentration- and time-dependent manner, achieving a near 2-log reduction at 6 hours with a concentration 10 times the MIC [1].

Nosiheptide (20 mg/kg; intraperitoneal injection; administered at 1 and 8 hours post-infection; female CD1 mice) significantly protects against mortality, with all 10 treated mice surviving by day 3, compared to 6 out of 10 control mice dying on day 1[1].