What is often considered a hallmark of pneumonia caused by infection with S. pneumoniae?

Pneumonia caused by Streptococcus pneumoniae typically presents with purulent sputum. This is due to the nature of the infection, as S. pneumoniae is a common bacterial pathogen known for eliciting an acute inflammatory response in the lungs. As the infection develops, neutrophils and other immune cells invade the respiratory tract to combat the bacteria, leading to the production of thick, yellow or green sputum that signifies the presence of pus.

Purulent sputum is particularly characteristic of bacterial pneumonia and can help differentiate it from viral pneumonia, which may present with more clear or watery secretions. The presence of purulent sputum, alongside other classic symptoms such as fever, chills, and cough, can provide a strong clinical clue to the underlying infectious process caused by S. pneumoniae.

The other options may also occur in pneumonia cases but are not specifically indicative of S. pneumoniae. A dry cough is less typical in these cases, as a productive cough is more common with bacterial pneumonias. Chest pain can be associated with pneumonia due to pleuritic inflammation, but it is not as definitive as the presence of purulent sputum. Fever without chills can occur in various infections but does not specifically identify the causative agent.