Infectious disease

Tetracyclines song

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Tetracyclines

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Key points in this song10

Tetracyclines inhibit bacterial protein synthesis by binding the 30S ribosomal subunit, blocking aminoacyl-tRNA attachment at the A site.
They are bacteriostatic and work against a broad spectrum including gram-positives, gram-negatives, atypicals, and intracellular organisms.
Classic indications include Chlamydia, Mycoplasma, Rickettsia, Borrelia burgdorferi (Lyme disease), and Vibrio cholerae.
Doxycycline is the drug of choice for Rocky Mountain spotted fever, including in children when the benefit outweighs the risk of tooth discoloration.
Tetracyclines chelate divalent cations (Ca²⁺, Mg²⁺, Fe²⁺, Al³⁺), so antacids, dairy, and iron supplements significantly reduce their oral absorption.
Key adverse effects include photosensitivity, GI upset, esophageal ulceration, and dose-dependent hepatotoxicity.
Tetracyclines are contraindicated in pregnancy and children under 8 years due to permanent tooth discoloration and inhibition of bone growth.
Demeclocycline is a tetracycline analog used to treat SIADH by inducing nephrogenic diabetes insipidus, blocking ADH action in collecting ducts.
Resistance most commonly occurs via plasmid-encoded efflux pumps that actively transport the drug out of bacterial cells.
Minocycline is notable for causing vestibular toxicity (vertigo, ataxia) and is used for acne vulgaris and MRSA in outpatient settings.