A 34-year-old man comes to the office due to a painless penile ulcer, which he first noticed 3 days ago. He had unprotected sexual intercourse with a new partner a few weeks ago. The patient has no significant medical history and takes no medications. Temperature is 37.1 C (98.8 F). Examination reveals a 2-cm nontender ulcer close to the glans penis with a raised, indurated margin and a clean base. There are no surrounding lesions or vesicles. There are several bilateral enlarged inguinal lymph nodes, which are firm, nontender, and rubbery. Physical examination is otherwise unremarkable. Rapid plasma reagin and HIV testing are negative. Infection with which of the following is the most likely cause of this patient's symptoms?

Question

A 34-year-old man comes to the office due to a painless penile ulcer, which he first noticed 3 days ago.  He had unprotected sexual intercourse with a new partner a few weeks ago.  The patient has no significant medical history and takes no medications.  Temperature is 37.1 C (98.8 F).  Examination reveals a 2-cm nontender ulcer close to the glans penis with a raised, indurated margin and a clean base.  There are no surrounding lesions or vesicles.  There are several bilateral enlarged inguinal lymph nodes, which are firm, nontender, and rubbery.  Physical examination is otherwise unremarkable.  Rapid plasma reagin and HIV testing are negative.  Infection with which of the following is the most likely cause of this patient's symptoms?

Quizplus · Accepted Answer

Eductional Objective: Patients with early syphilis (eg, chancre) often have false-negative initial serologic testing.  Direct visualization of the organism (Treponema pallidum) by dark-field microscopy or fluorescent antibody testing is the gold standard for diagnosis but is not widely available.

A 34-Year-Old Man Comes to the Office Due to a Painless