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After completing this case study, the reader should be able to:

  • Interpret drug allergy information (eg, timing of the reaction, signs, and symptoms) to identify the likelihood of an IgE-mediated reaction.

  • Assess the potential for cross-sensitivity between penicillins and carbapenems.

  • Differentiate desensitization from graded challenge dosing procedures and identify patients who are appropriate candidates for each procedure.

  • Select appropriate antibiotic therapy for a patient with multiple antibiotic allergies.


Chief Complaint

“My cough is back and I feel like I did when I was admitted two weeks ago.”


Alan Adams is a 55-year-old man with a history of COPD who presents today to the pulmonary clinic for a follow-up visit. Two weeks ago, he presented to the ER complaining of a 3-day history of tiredness and a cough productive of greenish sputum. Sputum cultures at that time revealed Pseudomonas aeruginosa sensitive to aztreonam and cefepime with intermediate sensitivity to piperacillin–tazobactam and tobramycin. Due to his multiple antibiotic allergies, the patient underwent desensitization to cefepime. He was subsequently treated for 7 days with IV cefepime without incident. He was discharged from the hospital to his home 2 weeks ago. He has had four admissions this year for COPD and pneumonia.


  • COPD × 17 years

  • Chronic empyema secondary to bronchial pleural fistulae with chest tube placement 7 months ago

  • Right upper lobe abscess secondary to Candida and Aspergillus; S/P upper lobe lobectomy 11 years ago

  • HTN × 10 years

  • S/P MI 15 years ago


Lives with his mother; he is unemployed. He has a 40 pack-year smoking history. Admits to occasional alcohol use; denies use of recreational drugs.


  • Albuterol MDI two puffs Q 6 H PRN

  • Ipratropium MDI two puffs Q 6 H

  • Aspirin 325 mg PO once daily

  • Amlodipine 10 mg PO once daily

  • Prednisone 20 mg PO daily (initiated as 60 mg PO daily during previous hospital admission; plan was to taper the dose and discontinue therapy within 2 weeks of hospital discharge)


  • Ampicillin–sulbactam: facial edema, tongue swelling, and periorbital edema

  • Ceftazidime: urticarial rash on chest and face with shortness of breath

  • Codeine: nausea, pruritus


(+) Fatigue, fever, sore throat, shortness of breath, and cough with thick sputum; (–) nausea, vomiting, diarrhea, chills, or chest pain

Physical Examination


A 55-year-old Caucasian man appearing older than his stated age in moderate respiratory distress. He ...

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