A 41-year-old man comes to the emergency department due to 3 weeks of low-grade fever, productive cough, and a 4.5-kg (10-lb) weight loss. The patient drinks 10-12 beers a day. On physical examination, he appears cachectic. Poor dentition and clubbing of the fingers are noted. A foul-smelling sputum sample is expectorated and sent for Gram stain and culture. CT scan of the chest is shown in the image below: Empiric antimicrobial therapy should include coverage against which of the following pathogens?

Question

A 41-year-old man comes to the emergency department due to 3 weeks of low-grade fever, productive cough, and a 4.5-kg (10-lb) weight loss.  The patient drinks 10-12 beers a day.  On physical examination, he appears cachectic.  Poor dentition and clubbing of the fingers are noted.  A foul-smelling sputum sample is expectorated and sent for Gram stain and culture.  CT scan of the chest is shown in the image below:  Empiric antimicrobial therapy should include coverage against which of the following pathogens?

Quizplus · Accepted Answer

11ec160b_3c61_6662_9249_e1b7edbfca61_MD0001_00 This patient's excessive alcohol consumption, subacute pulmonary symptoms, and dense lung opacity with an air-fluid level are consistent with lung abscess. Most cases are due to aspiration of oropharyngeal flora into the alveoli during reduced levels of consciousness from drug or alcohol use disorder (which impairs cough and gag reflexes) or episodes of dysphagia (eg, previous stroke, esophageal stricture). Periodontal disease is frequently present, which increases the concentration of anaerobic bacteria in the gingival crevices. Facultative and strict anaerobic oral organisms such as Bacteroides, Prevotella, Fusobacterium, and Peptostreptococcus are the common pathogens, but most lung abscesses are polymicrobial. Manifestations typically include subacute fever, cough with foul-smelling sputum, night sweats, and weight loss; digital clubbing sometimes occurs. Diagnosis is usually made when chest imaging reveals a dense fluid collection or cavitary infiltrate (often with an air-fluid level) in dependent portions of the lung (eg, superior portion of lower lobe). Treatment with ampicillin/sulbactam or a carbapenem is considered first-line therapy due to excellent coverage of oral anaerobes and aerobic gram-positive organisms (eg, Streptococcus pneumoniae). Clindamycin was used in the past but is now reserved for those with penicillin allergies due to high risk of Clostridioides (formerly Clostridium) difficile infection. (Choice A) Mycoplasma pneumoniae is a cell wall-deficient bacteria that causes atypical pneumonia. Patients frequently have subacute cough and low-grade fever, but chest imaging usually demonstrates bilateral reticulo-nodular opacities. The presence of foul-smelling sputum and a cavitary infiltrate with an air-fluid level makes lung abscess more likely. (Choice B) Although gram-negative intestinal flora (eg, Klebsiella pneumoniae) can cause lung abscess, empiric treatment must target upper respiratory anaerobic organisms because they are present in most lung abscesses. (Choice C) Skin flora (eg, coagulase-negative staphylococci) are common causes of blood culture contaminants, but they do not typically cause pulmonary infection. (Choice D) Methicillin-resistant Staphylococcus aureus can cause hospital-acquired or post-viral pneumonia complicated by lung abscess formation. However, purulent, foul-smelling sputum is highly indicative of anaerobic infection rather than aerobic infection. In addition, S aureus is not a common cause of lung abscess in patients at high risk for aspiration (eg, alcohol/drug use). Educational objective: Patients with alcohol use disorder are at increased risk for lung abscess due to the aspiration of oral flora during periods of unconsciousness. Although many cases are polymicrobial, the main pathogens are strict and facultative anaerobic oral flora (eg, Bacteroides, Prevotella, Fusobacterium, Peptostreptococcus). Manifestations include subacute fever, cough, and foul-smelling sputum. __________ References: How important are anaerobic bacteria in aspiration pneumonia: when should they be treated and what is optimal therapy. (http://www.ncbi.nlm.nih.gov/pubmed/23398871) Etiology and outcome of community-acquired lung abscess. (http://www.ncbi.nlm.nih.gov/pubmed/20389050)

A 41-Year-Old Man Comes to the Emergency Department Due to 3