ACAAI Board Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

For patients with early syphilis who are allergic to penicillin, tetracyclines, macrolides, or ceftriaxone are viable treatment options. The primary reason for this is that these alternatives are effective against Treponema pallidum, the bacterium that causes syphilis.

Tetracyclines, such as doxycycline or tetracycline itself, have been shown to be effective in treating syphilis due to their ability to inhibit bacterial protein synthesis. Macrolides, including azithromycin and erythromycin, also possess activity against this organism. Ceftriaxone, a cephalosporin, is another broad-spectrum antibiotic that can be used, particularly in more severe or resistant cases, although it is not typically the first choice for early syphilis because of its cost and dosing regimen.

In contrast, some other options would not adequately cover the infection. For example, relying solely on cephalosporins would exclude effective alternatives that are proven for syphilis treatment. Similarly, mono-therapy with azithromycin is no longer recommended due to concerns about resistance and was found to be less effective than other options after studies showed increasing treatment failures.

Therefore, the combination of tetracyclines