Laboratory examination
Herpes
All patients with genital ulcers thought to be from an STD should be tested for syphilis and HIV regardless of other risk factors.1 This patient should additionally be tested for herpes simplex. A bacteriologic test for chancroid is not necessary, but the clinician who first saw the patient asked that we conduct the test for chancroid—a culture for the Haemophilus ducreyi bacterium.
Isolation of HSV in cell culture is the preferred virologic test for patients with genital ulcers.1Unfortunately, the sensitivity of culture declines rapidly as lesions begin to heal, usually within a few days of onset. Direct fluorescent antibody tests are also available. Both herpes culture and the direct fluorescent antibody test distinguish HSV-1 from HSV-2. Polymerase chain reaction assays for HSV DNA are highly sensitive, but their role in the diagnosis of genital ulcer disease has not been well-defined.
Most cases of recurrent genital herpes are caused by HSV-2. Specific serologic testing can be expensive, and is not needed at the time of the initial virologic screening. However, consider ordering the test at a subsequent visit, because the distinction between HSV serotypes influences prognosis and counseling. Also, because false-negative HSV cultures are common—especially with recurrent infection or healing lesions—type-specific serologic tests are useful for confirming a diagnosis of genital herpes.1 Herpes serologies can also be used to help manage sexual partners of persons with genital herpes.
Syphilis
The Venereal Disease Research Laboratory (VDRL) test or rapid plasma reagin (RPR) test should be used to detect syphilis. Both tests are used for nonspecific screening only, because they measure anticardiolipin antibodies. A positive result should be confirmed with a specific treponemal test such as a fluorescent treponemal antibody absorption test (FTA-ABS).
The results of these laboratory tests are not available immediately during the patient’s visit. If there was a high suspicion for syphilis, a dark field examination from the ulcer exudate could be used to look for spirochetes while the patient was still in the office. In this case, the suspicion for syphilis was low.
Treatment: Antivirals
The major question is whether the patient should be treated empirically with medication. The most likely diagnosis is herpes simplex. Randomized trials indicate that 3 antiviral medications— acyclovir, famciclovir, and valacyclovir—provide clinical benefit for genital herpes (level of evidence [LOE]=1a).1
The Centers for Disease Control and Prevention (CDC) 2002 treatment guidelines for STDs recommend the following medications for the first clinical episode of genital herpes:
- Acyclovir 400 mg orally, 3 times daily for 7–10 days or until clinically resolved, OR
- Acyclovir 200 mg orally, 5 times daily for 7–10 days or until clinically resolved, OR
- Famciclovir 250 mg orally, 3 times daily for 7–10 days or until clinically resolved, OR
- Valacyclovir 1 g orally, twice daily for 7–10 days or until clinically resolved.
Topical acyclovir is less effective than the oral formulaton and its use is discouraged.
The suspicion for syphilis is too low to warrant an intramuscular shot of penicillin, which is painful and can cause anaphylaxis in some patients. The likelihood of chancroid is too low to prescribe an oral antibiotic such as erythromycin.