Master Macrolides with Picmonic for Medicine

Macrolides are a group of antibiotics whose activity stems from the presence of a macrolide lactone ring. Commonly used macrolides include erythromycin, azithromycin, and clarithromycin. As a class, these drugs bind to the 23S rRNA of the 50S prokaryotic ribosomal subunit and inhibit protein synthesis by blocking translocation.

Macrolides inhibit protein synthesis by interfering with the elongation of the polypeptide chain of bacterial proteins and the translocation of the ribosomal subunit. These antibiotics bind to the 23S ribosomal RNA in the 50S subunit, which catalyzes the formation of the peptide bond.

Macrolides inhibit protein synthesis by interfering with the elongation of the polypeptide chain of bacterial proteins and the translocation of the ribosomal subunit. These antibiotics bind to the 23S ribosomal RNA in the 50S subunit, which catalyzes the formation of the peptide bond.

Erythromycin is a macrolide antibiotic with a spectrum similar to other macrolide drugs. It is first line for superficial ocular infections and Legionnaire's Disease. Erythromycin is especially associated with GI disturbances because it is a motilin agonist. Due to this, erythromycin is sometimes used to treat gastroparesis. It is also associated with prolonged QT intervals that can lead to Torsades.

Azithromycin, commonly called Zithromax or Zmax, is a macrolide antibiotic derived from erythromycin. This drug is commonly used to treat respiratory bacterial infections though it is used either second-line or in patients with a -cillin allergy. It is also effective against sexually transmitted infections, including Chlamydia. Azithromycin has been associated with cardiovascular effects, specifically prolongation of the QT interval. Prolongation of the QT interval can lead to torsades de pointes (TdP), an abnormal heart rhythm that can be fatal.

Clarithromycin is a macrolide antibiotic typically used to treat respiratory bacterial infections though it is used either second-line or in patients with a -cillin allergy. It is also used in acute exacerbations of chronic bronchitis, H. pylori infections and mycobacterium avium complex (MAC) prophylaxis in patients with HIV. Unlike erythromycin, clarithromycin is acid-stable and can be taken orally without being protected from gastric acids. Of all the drugs in its class, clarithromycin has the best bioavailability, which makes it more amenable to oral administration.

Gram-positive cocci are gram-positive organisms that absorb crystal violet on gram stain due to a thick peptidoglycan layer with a spherical shape. Gram-positive cocci include Staphylococcus and Streptococcus species. Macrolides are effective against gram-positive cocci.

Atypical pneumonias are typically characterized by a protracted course, lack of sputum production, and extra-pulmonary symptoms as compared to typical pneumonias. Common causes of atypical pneumonias include Mycoplasma pneumoniae, Chlamydia, and Legionella. Macrolide antibiotics are commonly used in the treatment of atypical pneumonias.

Chlamydia trachomatis is an obligate intracellular human pathogen that has three human serovars that cause diseases, including trachomas, urethritis, and lymphogranuloma venereum. Macrolides can also be used to treat infections caused by Chlamydia pneumoniae and Chlamydia psittaci.

Bacteria can become resistant to macrolides via alteration of the 23S rRNA binding site, usually by post-transcriptional methylation, a process of enzymatic modification of gene expression, RNA processing and impact on protein functioning.