- Lung abscess typically results from aspiration of oral flora.
- Polymicrobial infections are common and involve oral anaerobes (Prevotella spp., Peptostreptococcus, Fusobacterium, Bacteroides spp., and Actinomyces spp.). Microaerophilic streptococci (S. anginosus group), enteric gram-negative bacilli (Klebsiella pneumoniae), and S. aureus, including community-acquired MRSA, are less frequent causes.
- Risk factors include periodontal disease and conditions that predispose patients to aspiration of oropharyngeal contents (alcohol intoxication, sedative use, seizures, stroke, and neuromuscular disease).
Infections are indolent and may be reminiscent of pulmonary TB, with fever, chills, night sweats, weight loss, dyspnea, and cough productive of putrid or blood-streaked sputum for several weeks.
- Chest radiography is sensitive and typically reveals infiltrates with cavitation and air–fluid levels in dependent areas of the lung, such as the lower lobes or the posterior segments of the upper lobes. Chest CT can provide additional anatomic detail.
- Respiratory isolation and sputum testing for TB should be performed on all patients with cavitary lung lesions.
- Antibiotic therapy should consist of clindamycin or a β-lactam/β-lactamase inhibitor (ampicillin–sulbactam, piperacillin–tazobactam, amoxicillin–clavulanate) or a carbapenem (ertapenem). For MRSA cavitary lung lesions, linezolid or vancomycin should be used. Metronidazole monotherapy is ineffective due to the presence of microaerophilic nonculturable organisms in the oral microbiota; thus, it should be combined with penicillin.
- Percutaneous drainage or surgical resection is rarely necessary and should be reserved for antibiotic-refractory disease, usually involving large abscesses (>6 cm) or infections with resistant organisms.
- Chapter 14: Treatment of Infectious Diseases
- Principles of Therapy
- Toxin-Mediated Infections
- Toxic Shock Syndrome
- Skin, Soft-Tissue, and Bone Infections
- Purulent Skin and Soft-Tissue Infections (Furuncles, Carbuncles, Abscesses)
- Nonpurulent Skin and Soft-Tissue Infections (Erysipelas and Cellulitis)
- Complicated Skin and Soft-Tissue Infections
- Infected Decubitus Ulcers and Limb-Threatening Diabetic Foot Ulcers
- Necrotizing Fasciitis
- Anaerobic Myonecrosis (Gas Gangrene)
- Central Nervous System Infections
- Bloodstream Infections and Catheter-Related Bloodstream Infections
- Cardiovascular Infections
- Upper Respiratory Tract Infections
- Lower Respiratory Tract Infections
- Gastrointestinal and Abdominal Infections
- Genitourinary Infections
- Fungal and Atypical Organisms
- Tick-Borne Infections
- Mosquito-Borne Infections
- Bite Wounds
- Health Care-Associated Infections
- Bioterrorism and Emerging Infections
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