A 62-year-old man is brought to the emergency department after his roommate found him with altered consciousness. The roommate reports that the patient has had three days of high fevers and cough with shortness of breath for the past day. He also reports that the patient has had chills, nausea, and dark sputum when he coughs. Medical history is significant for hypertension, 60 pack-year smoking history, heavy alcohol use, liver disease, and a hospitalization for Pseudomonas pneumonia 6 weeks ago. Physical examination shows an emaciated man with a decreased level of consciousness. Cardiopulmonary examination reveals tachycardia decreased breath sounds in the right lower lung field. Chest x-ray shows an infiltrate in the right lower lobe.
A) Cefepime plus doxycycline
The clinical presentation is consistent with a lobar pneumonia. The dark (currant jelly) appearance of the sputum and history of alcohol abuse makes Klebsiella a more likely cause, and the recent history of Pseudomonas infection requires coverage for this organism. The rate of Klebsiella infection is increased in individuals with impaired host defenses such as diabetes mellitus, alcoholism, hepatobiliary disease, and malignancy. For patients with community-acquired pneumonia admitted to the hospital, empiric antibiotic regimens should cover S. aureus and gram-negative enteric bacilli (e.g., Klebsiella pneumoniae) in addition to typical pathogens (e.g., S. pneumoniae, H. influenzae, and M. catarrhalis) and atypical pathogens (e.g., Legionella pneumophlia, M. pneumoniae, and C. pneumoniae). The key factors in selecting an initial regimen for hospitalized patients with community-acquired pneumonia are risk of infection with Pseudomonas and/or methicillin-resistant S. aureus (MRSA). The strongest risk factors for MRSA or Pseudomonas infection are known colonization or prior infection with these organisms, particularly from a respiratory tract specimen. Klebsiella is reliably susceptible to cephalosporins such as ceftriaxone.
An anti-pseudomonal cephalosporin such as cefepime would provide coverage for typical organisms, S. aureus, and Klebsiella in addition to Pseudomonas. Doxycycline would provide coverage for the atypical organisms. The other regimens would not provide coverage for Pseudomonas.
Key Learning Point
The key factors in selecting an initial regimen for hospitalized patients with community-acquired pneumonia are risk of infection with Pseudomonas and/or methicillin-resistant S. aureus (MRSA). The strongest risk factors for MRSA or Pseudomonas infection are known colonization or prior infection with these organisms, particularly from a respiratory tract specimen. Antibiotics that cover Pseudomonas include antipseudomonal beta-lactams (piperacillin-tazobactam, cefepime, ceftazidime, meropenem, or imipenem) or antipseudomonal fluoroquinolones (ciprofloxacin or levofloxacin).
