Family Nurse Practitioner Exam

Which bacterium is responsible for the highest mortality in patients with community-acquired pneumonia?

1. Streptococcus pneumoniae

2. Mycoplasma pneumoniae

3. Moraxella catarrhalis

4. Haemophilus influenzae

The correct answer is: Streptococcus pneumoniae

Streptococcus pneumoniae is recognized as the leading cause of bacterial community-acquired pneumonia and is associated with the highest mortality rates among patients afflicted with this condition. It is a virulent pathogen capable of causing severe illness, particularly in vulnerable populations such as the elderly, young children, and those with underlying health conditions. The virulence factors of Streptococcus pneumoniae, including its polysaccharide capsule and ability to evade the immune system, contribute significantly to its lethality. Moreover, this bacterium is commonly linked to more severe clinical presentations, including empyema and sepsis, which can further elevate mortality risks. This contrasts with the other pathogens listed; for example, Mycoplasma pneumoniae generally causes a milder form of pneumonia and is associated with fewer complications. Moraxella catarrhalis and Haemophilus influenzae, while they can cause pneumonia, are typically implicated in cases with less severe outcomes and lower mortality compared to Streptococcus pneumoniae. Understanding the impact and complications associated with different pathogens helps inform appropriate treatment and management strategies in clinical practice.