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.
Extra info: Erythromycin is the drug of choice for atypical pneumonia’s such as mycoplasm infection.
Erythromycin is an alternative to penicillin for treating pneumococcal meningitis.
Extra info: Erythromycin is not able to pass the blood-brain barrier.
Erythromycin is an alternative to penicillin for streptococcal pharyngitis.
Extra info: When penicillin is not effective, macrolides can be used.