An otherwise well 32-yo female developed community-acquired pneumonia (CAP) refractory to a five-day course of oral azithromycin. Her cough was non-productive. Despite a PSI of 42, she was hospitalized because of hypoxemia and failure of outpatient management.
Empiric therapy with ceftriaxone and azithromycin was initiated. Blood and airway cultures failed to detect a pathogen. Urine antigen tests for Legionella pneumophila and Streptococcus pneumoniae were negative. The clinical syndrome was felt compatible with an “atypical” CAP.
It is helpful to divide the etiologies of atypical pneumonia into those considered as non-zoonotic versus those associated with contact with an animal(s). Common non-zoonotic pathogens include Mycoplasma pneumoniae, Legionella spp., and Chlamydophila pneumoniae.
The patient’s pneumonia continued to worsen over the next 24 hours, despite escalating antibiotic therapy. She repeatedly denied direct or indirect exposure to animals. However, a friend of the patient recalled that the patient recently prepared a deer carcass.
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After two days, the patient's oxygen requirement increased, and vancomycin plus piperacillin-tazobactam were added.