In vitro activity of tylosin and its derivatives against Ureaplasma urealyticum.

Antimicrobial activity of tylosin (CAS 1401-69-0) and five other 16-membered macrolides biosynthesized by Streptomyces fradiae (lactenocin, desmycosin, macrosin (CAS 11049-15-3), relomycin (CAS 1404-48-4) and 5-O-mycaminosyl tylonolide) against Ureaplasma urealyticum was studied. The lowest minimum inhibitory concentrations (MIC) showed 5-O-mycaminosyl tylonolide, tylosin and descomysin. Absence of the aldehyde group in the structure of relomycin resulted in loss of the antimicrobial activity. Tylosin, desmycosin and macrocin proved better antimicrobial effect in the alkaline medium than in the acidic one.