Macrolides inhibit protein synthesis and thus are bacteriostatic. After binding the 50S ribosomal subunit they inhibit the movement of the ribosomal complex along the mRNA. The binding to the ribosomal subunit is reversible. Resistance to macrolides can be acquired by the following mechanisms:

  • efflux of the drug by an active pump in the cell wall
  • production of ribosomal protection proteins
  • hydrolysis of macrolides by esterases of Enterobacteriaceae


Macrolides like the classic erythromycin can be used as an alternative for benzylpenicillin in case of penicillin allergy. Furthermore, this group of drugs is used in the treatment of infections with Legionella, Mycoplasm, H. pylori, Gonorrhea, Chlamydia, and Campylobacter. Erythromycin can cause allergic reactions (fever, eosinophilia and skin eruptions). A more serious toxic effect is the induction of cholestatic hepatitis. Clarithromycin and azithromycin have a slightly better profile of pharmacokinetics and adverse effects.


Erythromycin is a suitable antibiotic to treat pneumonia cause by Mycoplasma pneumoniae.


Erythromycin is an alternative to penicillin for treating pneumococcal meningitis. 


Erythromycin is an alternative to penicillin for streptococcal pharyngitis.