What infections can cause pulmonary cavitations?

Infectious Causes of Pulmonary Cavitations

The most common infectious causes of pulmonary cavitations include tuberculosis, nontuberculous mycobacteria, fungi (particularly Aspergillus and Coccidioides species), and necrotizing bacterial pneumonia. 1, 2

Bacterial Causes

• Staphylococcus aureus is a frequent cause of necrotizing pneumonia that can lead to cavity formation with fluid collections 1
• Gram-negative bacteria including Klebsiella, Pseudomonas, and Legionella can cause cavitary pneumonia 3
• Escherichia coli can rarely cause cavitating necrotizing pneumonia, particularly in patients with uncontrolled diabetes 3
• Nocardia asteroides and Rhodococcus equi can produce cavitary lesions, especially in immunocompromised hosts 4
• Anaerobic bacteria can cause lung abscesses with cavitation 5

Fungal Causes

• Aspergillus species can cause chronic cavitary pulmonary aspergillosis (CCPA), characterized by multiple expanding thick-walled cavities that may contain aspergillomas (fungus balls) 6, 7
• Coccidioides species can lead to chronic cavitary pneumonia with persistent symptoms including sputum production, chest discomfort, and hemoptysis 6, 1
• Other endemic fungi that can cause cavitary lesions include Histoplasma, Blastomyces, and Paracoccidioides 2
• Fungal superinfections commonly occur within pre-existing bacterial cavities, forming fungus balls (mycetomas) 6, 1
• Cryptococcosis, though uncommon, can present with cavitary lesions, particularly in immunocompromised patients 4

Mycobacterial Causes

• Tuberculosis is the most common cause of chronic pulmonary infection with cavitation 2
• Nontuberculous mycobacteria (NTM), particularly Mycobacterium kansasii, frequently produce cavitary lesions 4
• Mycobacterium avium complex can cause lung disease but less commonly produces cavities compared to M. kansasii 4

Parasitic Causes

• Paragonimus westermani (lung fluke) can cause chronic cavitary lung disease 2

Risk Factors and Clinical Considerations

• Immunocompromised status significantly increases risk for cavitary infections, particularly in HIV-infected patients with low CD4+ counts 1, 4
• Pre-existing lung disease predisposes to cavity formation, especially with fungal infections 1
• The presence of pulmonary cavities is associated with increased risk of fungal and bacterial co-infection 8
• Cavities adjacent to the pleura have increased risk of rupture, leading to pneumothorax or pyopneumothorax 1

Radiographic Features

• Aspergillus-related cavitation typically presents as thick-walled cavities that may contain fungal balls visible as solid oval masses partially surrounded by a crescent of air ("air-crescent" sign) 6, 7
• Cavitations and the air-crescent sign typically occur during or after recovery from granulocytopenia in invasive fungal infections 6
• The "halo sign" (ground-glass opacification surrounding nodules) is highly suggestive of invasive pulmonary mold infection in granulocytopenic patients 6
• Early recognition of central hypodensity ('hypodense' sign) of pulmonary infiltrates represents a valuable diagnostic sign indicating fungal angiotropism 6

Diagnostic Approach

• High-resolution CT (HRCT) is preferred over chest X-rays for detecting cavitation and should be performed when cavitation is suspected 6, 7
• Microbiological sampling is essential, including sputum cultures for bacteria, fungi, and mycobacteria 7
• For fungal causes like coccidioidomycosis, serologic testing is important, though a negative test doesn't rule out infection 1
• Bronchoscopy should be considered in patients below the age of 55 years who have multilobar disease and are nonsmokers when evaluating non-resolving pneumonia 6

Complications

• Superinfection with bacteria or fungi within existing cavities is a common complication 6, 1
• Hemoptysis can occur, ranging from mild to severe and life-threatening 1
• Rupture of cavities into the pleural space can result in pyopneumothorax 1
• Fungus ball formation within cavities can occur with various fungi, including Aspergillus species and Coccidioides species 6

Treatment Considerations

• For symptomatic chronic cavitary coccidioidal pneumonia, oral azole antifungals (fluconazole or itraconazole) are recommended for at least 1 year 6
• Surgical intervention should be considered when cavities have been present for more than 2 years and if symptoms recur whenever antifungal treatment is stopped 6
• For ruptured coccidioidal cavity, prompt decortication and resection of the cavity is recommended 6
• Treatment should be pathogen-directed based on culture and sensitivity results 1