A 45-year-old man comes to the emergency department due to 3 weeks of fever, malaise, and cough productive of foul-smelling, purulent sputum. Six weeks ago, the patient was hospitalized after sustaining a head injury during a motor vehicle collision; he briefly required intubation and was discharged from the hospital 4 weeks ago. He does not use tobacco, alcohol, or illicit drugs. Temperature is 39.1 C (102.3 F), blood pressure is 120/74 mm Hg, pulse is 110/min, and respirations are 14/min. Laboratory studies reveal a hemoglobin of 12.5 g/dL and leukocyte count of 18,000/mm³. X-ray of the chest is shown in the exhibit. Sputum cultures are obtained. Which of the following is the most appropriate next step in management of this patient?

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11ec25c8_d948_3e6a_bc81_3332035fa2b1_MD0003_00 This patient's subacute fever, malaise, leukocytosis, cough productive of foul-smelling sputum, and cavitary lung infiltrate with an air-fluid level indicate lung abscess. Most lung abscesses are caused by the aspiration of oropharyngeal anaerobic bacteria (eg, Peptostreptococcus, Prevotella, Fusobacterium) due to swallowing dysfunction or periods of impaired consciousness (eg, substance/alcohol use disorder, general anesthesia, head trauma). The inoculated area develops pneumonitis, which typically evolves over 7-14 days into a necrotic infection, characterized radiologically by a lung cavity with air-fluid level. lung cavity with air-fluid level Common manifestations include subacute fever and malaise, cough with putrid sputum (highly specific for anaerobic infection), leukocytosis, and anemia of chronic disease. Although sputum culture should be attempted, anaerobic lung infections are difficult to identify on culture because the sample can be contaminated with other bacteria, including upper respiratory (eg, gingival) anaerobes, during collection. Therefore, patients with suspected lung abscess generally receive empiric antibiotic therapy; ampicillin-sulbactam (or a carbapenem) is used most commonly due to excellent pulmonary penetration and activity against obligative and facultative anaerobes. Clindamycin was considered a first-line agent but is now reserved for those who have beta-lactam allergy due to the risk of Clostridioides (formerly Clostridium) difficile infection. (Choice B) Bronchoscopy and biopsy can diagnose lung malignancy when a suspicious pulmonary lesion is present. Although squamous cell carcinoma often causes a cavitary lung lesion, it primarily occurs in smokers and is not typically associated with foul-smelling sputum, subacute fever, and leukocytosis. (Choice C) Metronidazole has excellent efficacy against obligate anaerobes but minimal efficiency against facultative anaerobes. Because lung abscesses are often a mixture of obligate and facultative anaerobes, metronidazole is not recommended (failure rates >50%). (Choice D) In patients with lung abscess, sputum culture results should be interpreted with caution due to the risk of sample contamination, including with upper respiratory flora. In addition, a lung abscess is a necrotizing infection; observation would increase the risk of sequalae and death. (Choice E) Surgical resection is sometimes required when a lung abscess does not respond to therapy or is very large (>6 cm). However, most resolve with empiric antibiotic therapy. Educational objective: Lung abscess is typically marked by subacute fever, putrid-smelling sputum, and a cavitary lung infiltrate with air-fluid level in a dependent portion of the lung. Patients often have history of swallowing dysfunction or impaired consciousness. Sputum culture should be obtained but is rarely useful; empiric treatment with ampicillin-sulbactam or a carbapenem is recommended.

A 45-Year-Old Man Comes to the Emergency Department Due to 3