Serum rapid plasma reagin and herpes simplex virus PCR testing are negative. Which of the following is the best next step in management of this patient?

Question

Serum rapid plasma reagin and herpes simplex virus PCR testing are negative.  Which of the following is the best next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d9e3_1ee3_bc81_03510286e1a5_MD0003_00 This patient with a painless genital ulcer (ie, chancre) and bilateral inguinal lymphadenopathy almost certainly has primary syphilis, despite negative serology testing. Two types of syphilis serologic tests are usually used in combination for diagnosis: Nontreponemal (eg, rapid plasma reagin [RPR]) Treponemal (eg, fluorescent treponemal antibody absorption [FTA-ABS]) In general, nontreponemal testing (eg, RPR) is obtained first due to low cost and availability. An initial RPR titer can also be used later to monitor response to treatment (ie, decreasing titers). However, nontreponemal testing has a higher rate of false-negative results (20%-30%), particularly for primary syphilis. This is because testing depends on the patient's development of antibodies, which may be absent or low in patients with early infection or severe immunosuppression. This patient could undergo treponemal testing, which is more sensitive, but her classic clinical presentation for primary syphilis is a strong indication for empiric treatment with intramuscular benzathine penicillin G. Empiric treatment reduces the risk of transmission. Repeat nontreponemal serology is performed in 2-4 weeks to establish baseline titers for treatment monitoring; a 4-fold titer decrease at 6-12 months confirms adequate treatment. (Choices A and B) Acyclovir can treat genital herpes outbreaks caused by herpes simplex virus (HSV). HSV tends to cause multiple, painful ulcers, but this patient has a single, painless lesion with negative HSV PCR testing. Azithromycin can be used to treat chlamydial infections, including lymphogranuloma venereum, which causes multiple genital ulcers and large, painful inguinal lymphadenopathy (ie, buboes), which are not seen in this patient. (Choice D) Treatment should not be delayed because transmission risk is high with an active syphilitic chancre. In addition, patients may not return for treatment because untreated chancres resolve spontaneously; however, syphilis infection may persist and can spread systemically. (Choice E) Topical corticosteroids are used to treat vulvar lichen planus and lichen sclerosus; however, these conditions usually do not present as a painless ulcer and are unlikely in this young patient. (Choice F) A wide local excision may be indicated for vulvar cancer, which can present as a single vulvar ulcer. In contrast to this patient, vulvar cancer typically causes pruritic, friable lesions over the course of months, not days. Educational objective: False-negative nontreponemal serology (eg, rapid plasma reagin) is common in primary syphilis. Patients with negative serology and strong clinical evidence (eg, chancre) of primary syphilis are treated empirically with intramuscular benzathine penicillin G. References: Recent trends in the serologic diagnosis of syphilis. (http://www.ncbi.nlm.nih.gov/pubmed/25428245)

Serum Rapid Plasma Reagin and Herpes Simplex Virus PCR Testing