Final answer:
Alternative antibiotics such as tetracycline, doxycycline, and erythromycin can be used to treat syphilis in patients allergic to penicillin.
Step-by-step explanation:
If a patient is allergic to penicillin, alternative antibiotics can be used to treat syphilis. Some options include tetracycline, doxycycline, and erythromycin. However, it is important to note that these alternative antibiotics are generally less effective than penicillin in treating syphilis and may require retesting after treatment to ensure a cure has occurred. It is recommended to consult with a healthcare professional to determine the best alternative treatment option for penicillin-allergic patients with syphilis.