ICD-10 Specific code A51: Early syphilis

Ceftriaxone is an antibacterial for systemic use, a third-generation cephalosporin. It inhibits bacterial cell wall synthesis following attachment to penicillin binding proteins (PBPs) leading to bacterial cell lysis and death.

Tetracyclines have a broad spectrum of anti-microbial activity and act by interfering with bacterial protein synthesis. They are active against a large number of gram positive and gram negative pathogenic bacteria, including some which are resistant to penicillin.

Erythromycin exerts its antimicrobial action by binding to the 50S ribosomal sub-unit of susceptible microorganisms and suppresses protein synthesis. Erythromycin is bacteriostatic and bactericidal depending on its concentration and the type of organism.

Minocycline is a semi-synthetic derivative of tetracycline. Minocycline inhibits protein synthesis in susceptible bacteria. In common with other tetracyclines it is primarily bacteriostatic and has a similar spectrum of activity to other tetracyclines.

Tetracyclines are taken up into sensitive bacterial cells by an active transport process. Once within the cell they bind reversibly to the 30S subunit of the ribosome, preventing the binding of aminoacyl transfer RNA and inhibiting protein synthesis and hence cell growth.