This is a gram-negative organism that is commonly associated with hospital-acquired pneumonia and generally affects debilitated or immunocompromised individuals, which does not fit with the patient's scenario.

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia. The bug is typically described as an encapsulated, lancet-shaped, gram-positive diplococci. This is the most accurate organism to fit the patient's clinical scenario and lab findings.

The morphological description of Haemophilus influenzae is small, pleomorphic, gram-negative coccobacilli. It does not match with the lab findings in the question.

Staphylococcus aureus is a gram-positive cocci that forms clusters, not typically seen as diplococci, and does not typically cause this type of pneumonia in healthy adults without predisposing factors.