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Chief Complaint

“Someone from the emergency department called me to recommend I come back to the hospital to receive treatment for syphilis. They said because I am pregnant that I need to receive treatment at the hospital.”

History of Present Illness

A 28-year-old female with a PMH of an allergy to amoxicillin (anaphylaxis) initially presented to the emergency department about 1 week ago for a painless sore on her inner labia. She reported unprotected sex with a new sexual partner about 3 weeks ago. A rapid pregnancy test was positive. She underwent testing for STI’s including RPR given clinical presentation consistent with primary syphilis. Today her Syphilis RPR resulted as reactive, RPR was reported “reactive” and reflex testing for RPR titer, and TP-PA were initiated. The patient was called back to the emergency department for desensitization and treatment of her primary syphilis with penicillin.

Student Work-Up

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Missing Information?


Patient Database

Drug Therapy Problems

Care Plan (by Problem)


  1. What signs and symptoms of anaphylaxis could the patient experience if penicillin were administered without desensitization?

    Hint: See Problematic Drug Classes and Treatment Options in PPP

  2. What are the treatments of choice for patient’s anaphylaxis?

    Hint: See Table 54-3 in PPP

  3. What classes of medications are frequently associated with anaphylaxis?

    Hint: See Table 54-2 in PPP

  4. What are the odds of cross-reactivity with β-lactams?

    Hint: See Problematic Drug Classes and Treatment Options in PPP

  5. How is the process of desensitization performed and where should it be performed?

    Hint: See Problematic Drug Classes and Treatment Options in PPP


The patient presents to the emergency department 3 months later with a chief complaint of dysuria and urinary frequency. A urinalysis was obtained and revealed positive for nitrites, large amounts of leukocyte esterase, and >25 WBC/hpf present. The doctor has asked you if it is okay to prescribe amoxicillin/clavulanate to treat the patients UTI since she was desensitized to penicillin for her syphilis treatment. What recommendation would you provide the physician?


Global Perspective

The study of medical genetics and their application to antimicrobials continues to evolve and expand. Abacavir is a generally well tolerated nucleoside reverse transcriptase inhibitor used in combination with other antiretrovirals for the treatment of HIV. Presence of at least one HLA*57:01 allele has been associated with type IV hypersensitivity reactions within the 1st 6 weeks of treatment. The frequency of HLA-B*57:01 allele is lowest in African and Asian populations, relatively common in European populations (~6-7%), and highest ...

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