Anaerobic Infections, Chest

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

Fever

Productive cough

Night sweats

Weight loss

Chronic course of illness

Poor dentition (frequently)

Pleural fluid culture

Chest radiograph

CT scan

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