A 28-year-old man comes to the office due to a rash. He has a history of seizure disorder and has been taking phenytoin for 6 years. Examination shows a diffuse, macular rash and lymphadenopathy. Biopsy of a lymph node is shown in the exhibit.

Treatment of this patient's condition is most likely to involve which of the following?

Question

A 28-year-old man comes to the office due to a rash. He has a history of seizure disorder and has been taking phenytoin for 6 years. Examination shows a diffuse, macular rash and lymphadenopathy. Biopsy of a lymph node is shown in the exhibit.

Treatment of this patient's condition is most likely to involve which of the following?

Quizplus · Accepted Answer

11ec160b_3bfd_73d3_9249_2bb51f68864a_MD0001_00 The presence of a generalized rash, lymphadenopathy, and a corkscrew-shaped organism on histopathology suggests secondary syphilis, a spirochetal infection caused by Treponema pallidum. Inoculation occurs via skin-to-skin contact during sexual intercourse; replication of T pallidum at the site of transmission results in an ulcer with heaped up borders (primary syphilis). Subsequent spread through the dermal lymphatic system leads to systemic spread. Secondary syphilis develops in untreated patients weeks or months after the chancre has resolved. Common manifestations include a diffuse, macular rash and generalized lymphadenopathy. The diagnosis is generally made with nontreponemal (eg, rapid plasma reagin) and treponemal-specific (eg, fluorescent treponemal antibody absorption) serologic testing because microscopy is technically difficult and less sensitive. However, dark-field microscopy or specialized silver stains can identify the spirochete. All stages of syphilis are most effectively treated with penicillin, a beta-lactam antibiotic that disrupts cell wall synthesis by inhibiting transpeptidase, a bacterial enzyme necessary for cell wall cross-linking. Because penicillin is effective only against bacteria that are dividing, and because T pallidum replicates slowly, penicillin preparations that provide prolonged exposure (eg, intramuscular penicillin G benzathine) are required. (Choice A) HIV is typically treated with reverse transcriptase and integrase inhibitors. Although acute HIV infection often presents with rash, lymphadenopathy, and constitutional symptoms a few weeks after transmission, a spiral-shaped organism would not be seen on biopsy. (Choice B) Phenytoin can cause a diffuse rash due to a delayed type IV hypersensitivity reaction. However, most cases arise within a few weeks of initiating therapy, not 6 years later. In addition, a corkscrew-shaped organism would not be seen on biopsy. (Choice C) Fluroquinolones (eg, ciprofloxacin) disrupt bacterial DNA synthesis by blocking bacterial DNA gyrase and topoisomerase. Fluroquinolones are often used for gram-negative bacterial infections (eg, urinary tract infection) but not for syphilis. (Choice E) Trimethoprim-sulfamethoxazole disrupts bacterial folate metabolism by blocking enzymes that generate dihydrofolic and tetrahydrofolic acid. This agent is often used for urinary tract and skin/soft tissue infection but is not used for syphilis. Educational objective: Syphilis is caused by the corkscrew-shaped organism Treponema pallidum. Secondary syphilis develops in untreated patients weeks or months after the initial infection, and presents with a diffuse, macular rash and generalized lymphadenopathy. First-line treatment is penicillin, which blocks the last step in bacterial cell wall synthesis (transpeptidation).

A 28-Year-Old Man Comes to the Office Due to a Rash