Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which organism is most commonly associated with chronic obstructive pulmonary disease (COPD)?

1. Streptococcus pneumoniae

2. H. influenzae

3. Mycoplasma pneumoniae

4. Chlamydia pneumoniae

The correct answer is: H. influenzae

H. influenzae is significantly associated with chronic obstructive pulmonary disease (COPD) because it commonly exacerbates respiratory infections in individuals with underlying lung conditions. This organism is known to contribute to both acute exacerbations and chronic inflammation in the airways, which is crucial in the context of COPD. Patients with COPD often have underlying bronchial inflammation and structural changes that can make them more susceptible to infections. H. influenzae can colonize the respiratory tract and cause infections that lead to worsening symptoms and further deterioration of lung function. In contrast, the other options listed, such as Streptococcus pneumoniae, Mycoplasma pneumoniae, and Chlamydia pneumoniae, although they can also cause respiratory infections, are not as specifically linked to the chronic inflammatory processes seen in COPD as H. influenzae is. The prominence of H. influenzae in the pathogenesis of COPD exacerbations is well-documented, making it the most relevant organism in this context.