PAEA Surgery End Of Rotation (EOR) Practice Exam

Which type of organisms is most commonly responsible for community-acquired pneumonia?

1. Viruses

2. Gram-negative bacteria

3. Gram-positive bacteria

4. Mycoplasma

The correct answer is: Gram-positive bacteria

Community-acquired pneumonia (CAP) is primarily caused by a variety of infectious agents, but gram-positive bacteria, particularly Streptococcus pneumoniae, are among the most common culprits. Streptococcus pneumoniae is responsible for a significant number of pneumonia cases, especially in adults. The prevalence of this bacterium in cases of pneumonia relates to its ubiquity in the community and its ability to cause respiratory tract infections. While viruses also frequently contribute to cases of pneumonia, particularly in children or during influenza seasons, the classic and most frequently tested organism in the context of community-acquired pneumonia is Streptococcus pneumoniae. Other potential causes, such as Mycoplasma pneumoniae and certain gram-negative bacteria, do exist, but they are less common compared to the standard presented by gram-positive bacteria, specifically the pneumococcus. This understanding is crucial for diagnosis and appropriate treatment, guiding clinicians to focus on antibiotic therapy that targets the most prevalent pathogens in community settings.