How does spiramycin fit into the macrolide antibiotic supply chain as erythromycin resistance grows?

How does spiramycin fit into the macrolide antibiotic supply chain as erythromycin resistance grows?
Spiramycin sits in the same macrolide family as erythromycin, and its acetylated derivative acetylspiramycin is a well-established semi-synthetic product. The key market angle is resistance: bacterial strains show no cross-resistance between erythromycin and josamycin, and roughly 90 percent of erythromycin-resistant staphylococcus strains remain sensitive to josamycin-type macrolides. Acetylspiramycin itself has weaker in-vitro activity than spiramycin, but after deacetylation in the body it converts back to spiramycin and delivers its antibacterial effect. That metabolic pathway keeps demand steady for the spiramycin III feedstock used to make the acetylated derivative, particularly for oral formulations treating respiratory, ENT and skin infections where erythromycin no longer works reliably.