Anaerobic Infections, Chest

Key Features

• Frequently occur in the setting of poor oral hygiene and periodontal disease, aspiration of saliva (which contains 10⁸ anaerobic organisms per milliliter in addition to aerobes)

• May lead to necrotizing pneumonia, lung abscess, and empyema

• Polymicrobial infection is the rule

• Anaerobes are frequently isolated etiologic agents, particularly

  • Prevotella melaninogenica

  • Fusobacteria

  • Peptostreptococci

Clinical Findings

• Fever

• Productive cough

• Night sweats

• Weight loss

• Chronic course of illness

• Poor dentition (frequently)

Diagnosis

• Pleural fluid culture

• Chest radiograph

• CT scan

Treatment

• Most pulmonary infections respond to antimicrobial therapy alone

• Preferred regimens

  • Clindamycin, 600 mg intravenously once, followed by 300 mg orally every 6–8 hours, or

  • Ampicillin/sulbactam, 3g intravenously every 6 hours, followed by amoxicillin/clavulanic acid, 875 mg/125mg orally twice daily

• Metronidazole is an alternative

  • But does not cover facultative streptococci, which are often present

  • So, if used, a second agent active against streptococci, such as ceftriaxone, 1 g intravenously or intramuscularly daily should be added

• Moxifloxacin, 400 mg intravenously or orally once daily may be used

• Because these infections respond slowly, a prolonged course of therapy (eg, 4–6 weeks) is generally recommended

• Percutaneous chest tube or surgical drainage is indicated for empyema