Rosh Emergency Medicine Practice Test

Which organism is most likely responsible for a nonproductive cough and fatigue in a young woman living in a dormitory?

1. Legionella pneumophila

2. Mycoplasma pneumoniae

3. Staphylococcus aureus

4. Streptococcus pneumoniae

The correct answer is: Mycoplasma pneumoniae

The identification of Mycoplasma pneumoniae as the likely organism responsible for a nonproductive cough and fatigue in a young woman living in a dormitory aligns with the common presentation of atypical pneumonia, also known as "walking pneumonia." Mycoplasma pneumoniae is particularly noted for causing respiratory infections in younger individuals, including college students and those living in close quarters such as dormitories. This organism causes a nonproductive cough due to its mechanism of action, which often results in inflammation of the airways without the classic lobar pneumonia that would be associated with more acute or severe pathogens. The fatigue can be attributed to the systemic inflammatory response triggered by the infection. Additionally, since Mycoplasma pneumoniae does not typically produce significant amounts of mucus, a nonproductive cough is a hallmark symptom. In contrast, Legionella pneumophila is often linked to more severe pneumonia, particularly in older populations or those with certain risk factors, and is less commonly seen in young, otherwise healthy individuals. Staphylococcus aureus tends to cause more severe respiratory illness or post-influenza infections, while Streptococcus pneumoniae usually presents with a productive cough and other typical symptoms of bacterial pneumonia. Thus, Mycoplasma pneumoniae is the most fitting