Erythromycin B is a macrolide antibiotic effective against a range of Gram-positive bacteria and some Gram-negative species. It inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, preventing peptide chain elongation. Commonly applied in treating respiratory tract infections, skin infections, and certain sexually transmitted diseases like chlamydia, especially in patients allergic to penicillin. Also used in veterinary medicine and as a growth promoter in animal feed. Its derivatives are explored for immunomodulatory and anti-inflammatory effects in chronic lung diseases.