tetracyclinefamily

The tetracycline family refers to a group of broad-spectrum antibiotics that share a four-ring naphthacene core and are produced by actinobacteria such as Streptomyces species. The core structure allows them to bind reversibly to the 30S subunit of bacterial ribosomes, blocking the attachment of aminoacyl-tRNA and inhibiting protein synthesis, which renders them bacteriostatic.

The spectrum includes many Gram-positive and Gram-negative bacteria, as well as atypical pathogens such as Chlamydia, Mycoplasma, and Rickettsia. They are commonly used to treat acne, rosacea, sexually transmitted infections caused by Chlamydia trachomatis, atypical pneumonias, Lyme disease, Rocky Mountain spotted fever, and other rickettsial diseases, as well as H. pylori–related infections in combination regimens. Doxycycline and minocycline have favorable pharmacokinetics with good oral bioavailability; tetracycline itself has reduced absorption when taken with divalent cations or dairy products. They are generally administered orally, but some forms are used topically or intravenously.

Adverse effects include gastrointestinal upset, photosensitivity, and, in developing teeth, tooth discoloration and enamel hypoplasia; esophageal irritation can occur if tablets are not taken with water. They are contraindicated in pregnancy and in children under 8 years old due to effects on tooth development, and should be used with caution in hepatic or renal impairment and during lactation. Resistance has risen due to efflux pumps and ribosomal protection proteins, reducing effectiveness in some pathogens.

Related derivatives such as glycylcyclines (for example, tigecycline) are structurally related but are distinct from the traditional tetracycline class. Prophylaxis and treatment decisions should consider current guidelines and local resistance patterns.