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

The correct answer is D. The etiology of pneumonia is related to both the age of the patient and the particular risk factors that he or she may exhibit. For patients with no specific risk factors, pneumonia is referred to as community-acquired pneumonia (CAP). CAP has a variable etiology depending on the age of the patient. In patients aged 29-55, the pneumococcus (Streptococcus pneumoniae), a gram-positive organism, is the most frequent agent causing so-called typical or bacterial pneumonia.

Bordetella pertussis (choice A) causes whooping cough in children. Most adults in the U. S. have been vaccinated against this organism. However, 20 years after the last booster, immunity begins to fade, and it is reasonably common to see patients aged 55 and older presenting with upper and lower respiratory tract infections caused by this organism. It is therefore now recommended to obtain an adult booster immunization against pertussis.

Klebsiella pneumoniae (choice B) is a reasonably frequent source of pneumonia in both hospitalized patients and those with chronic aspiration problems, such as post-stroke patients and alcoholics.

Mycoplasma pneumoniae (choice C) is the primary agent responsible for so-called atypical pneumonia in the same age bracket.

Staphylococcus aureus (choice E) is a gram-positive organism that causes severe cavitating pneumonia. It is most often responsible for pneumonia in diabetic patients and in patients with influenza pneumonia.

PEARL: Streptococcus pneumoniae is the most common cause of pneumonia worldwide. Pulmonary infection with Staph aureus can be seen in patients who also have concomitant infections with influenza (post-influenza pneumonia) and also in the elderly. The most common cause of pneumonia in patients with influenza is still Strep Pneumoniae but those with influenza are more likely to get pneumonia caused by Staph aureus as opposed to the general population.