Can Sporothrix schenckii Cause Lung Infection?
Yes, Sporothrix schenckii definitively causes pulmonary (lung) infection, though it is rare and occurs primarily through inhalation of conidia rather than the more common cutaneous inoculation route. 1
Mechanism and Epidemiology
Pulmonary sporotrichosis develops when S. schenckii conidia are inhaled into the respiratory tract, distinguishing it from the typical cutaneous inoculation route that causes most sporotrichosis cases 1
This form of infection is uncommon but well-documented in the medical literature, with specific treatment guidelines established by the Infectious Diseases Society of America 1
The infection typically manifests as chronic cavitary fibronodular disease on imaging 1
High-Risk Patient Populations
Middle-aged men with specific risk factors are most susceptible:
Chronic alcoholism is the most consistently identified risk factor 1
Chronic obstructive pulmonary disease (COPD) significantly increases susceptibility 1
Immunosuppressed patients including those with AIDS (low CD4+ counts), transplant recipients, and patients on corticosteroids or TNF antagonists are at elevated risk 1, 2, 3
Clinical Presentation and Prognosis
Pulmonary sporotrichosis presents with chronic progressive respiratory symptoms rather than acute illness 4
The outcome is usually poor, primarily due to two factors: delayed diagnosis (given the rarity of this presentation) and severe underlying pulmonary disease in affected patients 1
The infection can result in significant morbidity and mortality despite treatment 4
Critical Diagnostic Considerations
Diagnosis is often delayed because pulmonary sporotrichosis mimics other fungal and mycobacterial infections, particularly tuberculosis and histoplasmosis 5
In immunosuppressed patients with any form of sporotrichosis (cutaneous or lymphocutaneous), actively search for pulmonary and CNS dissemination 1, 5
Obtain sputum cultures on Sabouraud dextrose agar, though be aware that cultures may be negative despite active infection 5
Growth typically occurs within 8 days but may require up to 4 weeks of incubation 5
Treatment Implications
The existence of pulmonary sporotrichosis has important treatment ramifications compared to cutaneous disease:
Oral itraconazole alone (used for cutaneous disease) is insufficient for pulmonary sporotrichosis 1
Treatment requires more aggressive antifungal therapy, typically amphotericin B formulations 1, 6
Surgical resection combined with antifungal therapy achieves the highest cure rates (70-80%), compared to medical therapy alone which has cure rates around 50% or lower 6
Important Caveats
Bilateral apical cavitary disease has a dismal prognosis even with aggressive treatment 6
The rarity of this infection means treatment recommendations are based on case series and expert opinion rather than randomized controlled trials 6, 4
Donor-derived pulmonary sporotrichosis has been documented in lung transplant recipients, presenting within days of transplantation 3