Snapshot A 52-year-old man presents to the emergency department with a cough, foul-smelling sputum, and a subjective fever. He is homeless and has a history of alcohol-use disorder. His temperature is 102.2°F (39°C). A radiograph of the chest demonstrates a thick-walled cavitary lesion. He is admitted to the hospital for empiric antibiotic treatment. Introduction Definition parenchymal necrosis of the lung caused by a microbial infection this leads to the development of a circumscribed collection of pus Epidemiology Incidence most common cause is aspiration Etiology Pathophysiology Aspiration leads to bacterail inoculation in the lung parenchyma → lung parenchyma necrosis (within 7-14 days) → abscess formation foul smelling sputum results if the abscess communicates with the airway Anaerobic bacteria is the most common cause Polymicrobial in cases of aspiration Monomicrobial causes include group A streptococci Staphylococcus aureus (including MRSA) Klebsiella pneumoniae Nocardia (in immunocompromised patients) Presentation Symptoms cough foul-smelling sputum Physical exam weight loss fever Imaging Chest radiography indication imaging of choice and diagnostic in patients with signs and symptoms concerning for abscess findings cavity with an air-fluid level Studies Microbiology testing from sputum or respiratory specimen Differential Empyema differentiating factor radiography typically demonstrates opacifying lesion Treatment Medical intravenous empiric antibiotics indication login to view 1 more bullet medications login to view 4 more bullets Complications Death Prognosis Morbidity and mortality improved with antibiotics