We Often Get CAP Wrong: Case Challenges

Neil Gaffin, MD


June 13, 2019


We followed the second course and discontinued the antibiotics. The overall clinical picture, including the serial low procalcitonin levels, suggested RSV pneumonia. If bacterial pneumonia had seemed likely, then 5 days of therapy would be as effective as a longer course.[3]Given the myriad safety warnings, fluoroquinolones should be reserved for situations in which other agents cannot be used.[4] Although it could be argued that empirical coverage should have included Pseudomonas aeruginosa and MRSA, the negative sputum culture ruled out those pathogens. This patient improved and was discharged home a week later.

'Allergic to Penicillin'

A 64-year-old woman seen in the ED had a 4-day history of fever, chills, body aches, and cough, during which she was seen at urgent care. Testing for influenza was reportedly negative, and a chest x-ray "showed pneumonia." She was prescribed azithromycin, which she had been taking for 2 days before this admission, but was not improving. She reported no recent travel or sick contacts, and she is reportedly allergic to penicillin.

Upon arrival, her temperature was 102°F and her oxygen saturation on room air was 94%. A WBC count was 4700 cells/µL (with 15% bands). The procalcitonin level was 0.19 ng/mL. Polymerase chain reaction (PCR) assays for influenza A and B were negative. A chest x-ray revealed a consolidative left lower-lobe infiltrate (Figure 2).

Figure 2. Chest x-ray showing left lower-lobe infiltrate. Image courtesy of Neil Gaffin, MD.

The patient was started on aztreonam and doxycycline and admitted to a general medical floor. Respiratory pathogen testing the next day revealed adenovirus, and a repeat procalcitonin level was 0.19 ng/mL.


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