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

• Clindamycin, 600 mg intravenously once, followed by 300 mg every 6–8 hours orally, is the treatment of choice

• 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/day intravenously or intramuscularly should be added

• Penicillin, 2 million units every 4 hours intravenously, followed by amoxicillin, 750–1000 mg every 12 hours orally, is an alternative; however, penicillin-resistant Bacteroides fragilis and P melaninogenica are commonly isolated and have been associated with clinical failures

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

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