Tetracycline antibiotics

A class of broad-spectrum antibiotics derived from Streptomyces bacteria

Tetracycline antibiotics are a group of broad-spectrum antibiotics that are effective against a wide range of microorganisms, including gram-positive and gram-negative bacteria, chlamydiae, mycoplasmas, rickettsiae, and protozoan parasites. These antibiotics are derived from the bacterium Streptomyces and are characterized by their four-ring molecular structure.

Mechanism of Action

Tetracyclines work by inhibiting protein synthesis in bacteria. They achieve this by binding to the 30S ribosomal subunit, preventing the attachment of aminoacyl-tRNA to the ribosomal acceptor (A) site. This action effectively halts the addition of new amino acids to the nascent peptide chain, thereby inhibiting bacterial growth and reproduction.

Clinical Uses

Tetracyclines are used to treat a variety of infections, including:

• Acne vulgaris
• Cholera
• Brucellosis
• Plague
• Rickettsial infections such as Rocky Mountain spotted fever
• Chlamydia trachomatis infections
• Mycoplasma pneumoniae infections

Side Effects

Common side effects of tetracycline antibiotics include gastrointestinal disturbances such as nausea, vomiting, and diarrhea. They can also cause photosensitivity, leading to an increased risk of sunburn. Long-term use can result in discoloration of teeth and affect bone growth in children.

Resistance

Bacterial resistance to tetracyclines can occur through several mechanisms, including:

• Efflux pumps that expel the antibiotic from the bacterial cell
• Ribosomal protection proteins that prevent tetracycline binding
• Enzymatic inactivation of the antibiotic

Examples of Tetracyclines

Some commonly used tetracycline antibiotics include:

• Tetracycline
• Doxycycline
• Minocycline
• Tigecycline

History

The first tetracycline, chlortetracycline, was discovered in the late 1940s. It was isolated from Streptomyces aureofaciens. Since then, several derivatives have been developed to improve efficacy and reduce side effects.

Images

Chemical structure of tetracycline

File:Doxycycline.png

Chemical structure of doxycycline

Related Pages

• Antibiotic resistance
• Protein synthesis inhibitors
• Broad-spectrum antibiotics