Treatment failure in suspected community-acquired pneumonia revealing a pulmonary abscess

Community-acquired pneumonia (CAP) is a leading cause of hospitalization and mortality, with Streptococcus pneumoniae as a leading cause. Chest radiography, the standard initial imaging modality, can miss early complications, which lead to delays in diagnosis and treatment. Computed tomography (CT) provides greater detail in identifying complications. We report a 67-year-old male with chest pain who was treated in an outpatient setting with oral antibiotics for suspected CAP; however, he experienced clinical deterioration, including fever, cough, weight loss, and worsening respiratory symptoms. Repeat chest X-ray revealed increased lung opacities, prompting a CT thorax, which revealed a large pulmonary abscess not visualized on prior imaging. Failure of outpatient management required inpatient admission with intravenous antibiotics and CT-guided percutaneous drainage. A total of 450 mL of purulent fluid was drained, and cultures grew Streptococcus intermedius. The patient improved and was given targeted antibiotics. This case highlights the importance of considering less common pathogens such as S. intermedius in patients with prolonged symptoms or failure of outpatient therapy. CT imaging should be considered in patients who fail to improve, thus expediting diagnosis and guiding management. S. pneumoniae typically causes acute pneumonia with lobar consolidation. S. intermedius often causes necrotizing abscesses and empyema, often with a longer, more subacute presentation. Differentiating the two on initial presentation is quite difficult, as in our patient's case.