Which antibiotic is used to treat Treponema pallidum infections?

Treponema pallidum is the causative agent of syphilis, and penicillin is the antibiotic of choice for its treatment. Penicillin is effective against Treponema pallidum due to its ability to inhibit bacterial cell wall synthesis, which is crucial for the bacterium's viability. When penicillin is administered, it disrupts the formation of the peptidoglycan layer, leading to cell lysis and death of the bacteria.

The effectiveness of penicillin in treating syphilis is well-established, and it is particularly advantageous because it is not only safe and well-tolerated but also has a long track record of efficacy in clearing the infection and preventing complications associated with untreated syphilis.

In contrast, other choices do not have specific activity against Treponema pallidum. Sulfadiazine is a sulfonamide antibiotic that works by inhibiting bacterial folate synthesis but is not effective against Treponema pallidum. Cyclophosphamide is an alkylating agent used primarily as chemotherapy or immunosuppressant and does not have any antibacterial properties. Metronidazole is effective against anaerobes and certain protozoa but does not target syphilis or Treponema pallidum