Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum. This infection can affect various parts of the body if left untreated. Fortunately, syphilis can be effectively treated with antibiotics, especially when diagnosed and managed early. Early intervention helps prevent disease progression and long-term health consequences.
Antibiotics as Treatment
The primary and most effective antibiotic for treating all stages of syphilis is penicillin G. Benzathine penicillin G is a widely recommended formulation due to its established efficacy and safety. Penicillin has been the cornerstone of syphilis treatment for decades, effectively eliminating the Treponema pallidum bacterium.
For individuals with a penicillin allergy, alternative antibiotics like doxycycline and tetracycline are available. These alternatives may require longer treatment durations and are generally less preferred than penicillin, especially for pregnant individuals. Pregnant patients with a penicillin allergy are typically desensitized to penicillin, as it is the only therapy with documented efficacy for syphilis during pregnancy.
Syphilis Stages and Treatment
The approach to treating syphilis with antibiotics varies depending on the infection stage. Syphilis progresses through distinct stages: primary, secondary, latent (early and late), and tertiary. Each stage has specific treatment protocols.
For primary, secondary, and early latent syphilis (defined as acquired within the preceding year), a single intramuscular injection of 2.4 million units of benzathine penicillin G is typically sufficient. This single-dose regimen is effective due to the generally lower bacterial load in these early stages.
As the disease progresses, treatment becomes more complex, requiring multiple doses. For late latent syphilis or syphilis of unknown duration, the recommended treatment involves three weekly intramuscular injections of 2.4 million units of benzathine penicillin G, totaling 7.2 million units. Tertiary syphilis also typically requires this three-dose weekly regimen if the central nervous system is not involved.
Neurosyphilis, ocular syphilis, and otosyphilis occur when the infection spreads to the brain, eyes, or ears. These conditions necessitate a more intensive treatment approach, usually involving intravenous aqueous crystalline penicillin G. A typical regimen for neurosyphilis is 18-24 million units per day, administered as 3-4 million units intravenously every four hours, or by continuous infusion, for 10 to 14 days. This ensures adequate antibiotic penetration into the central nervous system.
After Treatment
After antibiotic treatment, regular follow-up testing is important to confirm therapy success. These evaluations typically involve serologic blood tests, such as non-treponemal tests like the Rapid Plasma Reagin (RPR) or Venereal Disease Research Laboratory (VDRL) tests.
Follow-up testing monitors the decline in antibody titers, which indicates a successful treatment response. For primary and secondary syphilis, clinical and serologic evaluations are usually performed at 6 and 12 months post-treatment. A fourfold decrease in the non-treponemal test titer within 6-12 months is generally considered a successful response. Treponemal tests, however, often remain reactive for life and are not used to monitor treatment success.
Preventing re-infection is also important. Individuals should avoid sexual contact with new partners until treatment is finished and any sores have healed. Notifying and treating sexual partners is also crucial to prevent re-exposure and interrupt transmission.
Why Treatment is Essential
Timely diagnosis and treatment of syphilis are important to prevent severe and irreversible health complications. If left untreated, syphilis can progress and cause widespread damage to various organ systems, with long-term issues manifesting years or even decades after the initial infection.
One significant complication is neurosyphilis, where the infection invades the brain and nervous system, leading to cognitive impairment, paralysis, blindness, or dementia. Cardiovascular syphilis can affect the heart and blood vessels, potentially causing inflammation and bulging of the aorta. Gummas, soft, tumor-like growths, can appear on the skin, bones, or internal organs, causing tissue destruction.
While antibiotic treatment can cure the infection and stop its progression, it cannot reverse any damage already occurred from long-term, untreated disease. Untreated syphilis also increases the risk of acquiring or transmitting HIV, as the genital sores it causes can facilitate viral entry. Prompt and complete treatment is crucial to safeguard overall health and prevent devastating outcomes.