Ease Into Prep with a PANCE^® Question of the Day

The correct answer is B. This patient, with a long history of chronic obstructive pulmonary disease (COPD), has evidence of a community-acquired pneumonia. The common organisms causing pneumonias in patients with COPD are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Patients who smoke are often colonized with Haemophilis influenza .

This patient has no other history suggestive of Escherichia coli (choice A) infection elsewhere (such as in the urinary tract), and primary E. coli pneumonia is rare.

Klebsiella pneumoniae (choice C) is typically found in alcoholic patients and the pneumonia often causes cavitations in the lung.

There is no evidence of tuberculosis (choice D) by history. Tuberculosis usually presents with a more chronic presentation. Furthermore, it would generally be found as an upper lobe infiltrate, consistent with reactivation tuberculosis. Much less commonly, tuberculosis may present as a primary infection, but this is generally seen in patients with an underlying immunocompromised state. In the setting of primary tuberculosis, a lower lung field pneumonia is in fact possible.

Mycoplasma pneumoniae (choice E) does not present with a lobar consolidation and is generally a disease of younger people who present with fever, malaise of at least several days duration, and a nonproductive cough. The chest x-ray film in a patient with Mycoplasma pneumonia would classically reveal faint bilateral interstitial infiltrates.

PEARL:

• Strep. pneumoniae is the most common cause of CAP.
• Non-typeable H. influenzae is an important cause of pneumonia in elderly adults and in patients with underlying pulmonary disease, such as cystic fibrosis and COPD and in those who continue to smoke.
• Mycoplasma pneumoniae is one of the most common causes of atypical pneumonia and is commonly seen in school-aged children, military recruits, and college students.
• Moraxella is a gram-negative diplococcus that can cause lower respiratory tract infections in immunocompromised persons and in patients with COPD.