We Often Get CAP Wrong: Case Challenges

Neil Gaffin, MD


June 13, 2019


We followed the first course. The patient remained stable and was discharged home the following day on no further antibiotics.

Viruses are a significant cause of CAP in the United States in 2019 and do not require treatment with antibiotics. Although empirical therapy is reasonable upon presentation, respiratory pathogen PCR assay and procalcitonin testing, if available, can assist in early cessation of antibiotics when bacterial infection is unlikely. In response to bacterial infection, procalcitonin becomes detectable within hours, not 5-7 days.[5] Minimizing unnecessary therapy translates into less risk for Clostridium difficile infection and less selective pressure for the emergence of resistant organisms. Chest radiography findings, regardless of pattern, cannot reliably distinguish between viral and bacterial pathogens.[6]

Penicillin allergy is the most commonly reported drug allergy in the United States. However, after undergoing a complete evaluation by a board-certified allergist, including skin testing, 90% of patients labeled as "penicillin-allergic" are able to tolerate penicillin. Up to 90% of those with a history of penicillin allergy do not in fact have true allergy.[7,8]

Is Mom Aspirating?

A 92-year-old woman was brought from a nursing facility to the ED with fever and shortness of breath. The patient's daughter described a few days of productive cough and rhinorrhea, with increasing respiratory congestion over the past 24 hours. The patient is wheelchair-bound and has dementia.

The ED evaluation found the following:

  • Temperature: 101.5°F

  • Blood pressure: 94/57 mm Hg

  • Room air oxygen saturation: 82%

  • WBC count: 17,500 cells/µL

  • Blood urea nitrogen: 29 mg/dL

  • Creatinine: 0.9 mg/dL

  • Weight: 39 kg

A chest x-ray (Figure 3) revealed a right lower-lobe infiltrate.

Figure 3. A severely rotated chest x-ray revealing a right lower-lobe infiltrate. Image courtesy of Neil Gaffin, MD

The patient was admitted with pneumonia and dehydration and started on intravenous fluids, ceftriaxone, and azithromycin. The next morning, she was afebrile and comfortable, eating her breakfast. Her oxygen saturation was 96% on 2 L/min oxygen via nasal cannula. The procalcitonin was 0.41 ng/mL, the WBC count was 10,700 cells/µL, and the respiratory pathogen panel revealed rhinovirus. She has received two doses each of ceftriaxone and azithromycin.


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