Tetracyclines are a class of antibiotics which are commonly used in clinical practice.

Examples

• doxycycline
• tetracycline

Mechanism of action

• protein synthesis inhibitors
• binds to 30S subunit blocking binding of aminoacyl-tRNA

Mechanism of resistance

• increased efflux of the bacteria by plasmid-encoded transport pumps, ribosomal protection

Indications

• acne vulgaris
• Lyme disease
• Chlamydia
• Mycoplasma pneumoniae

Notable adverse effects

• discolouration of teeth: therefore should not be used in children < 12 years of age
• photosensitivity
• angioedema
• black hairy tongue

Tetracyclines should not be given to women who are pregnant or breastfeeding due to the risk of discolouration of the infant's teeth.