American Board of Internal Medicine (ABIM) Certification Practice Exam

When evaluating severe community-acquired pneumonia, which cultures should be performed for diagnostics?

1. Sputum and blood cultures

2. Urine and throat swabs

3. Bronchoscopy and pleural fluid cultures

4. Stool and nasal swabs

The correct answer is: Sputum and blood cultures

In the evaluation of severe community-acquired pneumonia (CAP), obtaining sputum and blood cultures is essential for effective diagnosis and management. Sputum cultures provide direct insight into the etiology of the pneumonia by identifying the specific pathogen in the respiratory secretions. This is particularly important in severe cases, where the causative organisms may include atypical bacteria or bacterial pathogens that require specific antimicrobial therapy. Blood cultures are critical because they help identify if there is a systemic infection or bacteremia, which can occur in severe pneumonia cases. The early identification of the responsible pathogens can guide the choice of appropriate antibiotics, thereby improving outcomes and reducing complications. While other methods like urine, throat swabs, or bronchoscopy can play a role in specific circumstances, they are not standard in the initial evaluation of severe pneumonia compared to sputum and blood cultures. Urine cultures can be helpful for pneumococcal or legionella-specific tests but do not provide a comprehensive microbial profile of pathogens present in the lungs. Therefore, the combination of sputum and blood cultures is the most clinically relevant approach when diagnosing severe community-acquired pneumonia.