- Published on
KembaraXtra-Medicine – Aspergillosis
Aspergillosis is a group of illnesses caused by infection with Aspergillus species, a ubiquitous mold found worldwide in soil, building materials, and water. Humans are exposed mainly by inhaling airborne conidia (spores) that are small enough (about 2.5–3 μm) to reach the alveoli. Disease manifestations depend on the condition of the lungs, the host immune response, and the size of the inoculum. Aspergillus fumigatus is the most common human pathogen, while A. flavus is especially important in invasive disease and sinonasal involvement, and A. niger can also cause invasive infection. Hospital exposure can occur when unfiltered outside air enters through open windows or from contaminated water sources, and infections may also involve the nose, sinuses, external ear, or traumatized skin.
Risk is highest in immunocompromised patients, and invasive aspergillosis has become more common as modern therapies increasingly suppress immunity. Allogeneic stem cell transplant recipients and lung transplant recipients are among the highest-risk groups. A genetic deficiency of long pentraxin 3 (PTX3), which affects neutrophil antifungal function, may increase risk in hematopoietic stem-cell transplant patients. In advanced AIDS, patients with CD4 counts below 50/mm³ are more susceptible, although invasive aspergillosis remains otherwise uncommon in HIV. Severe influenza (including H1N1) can predispose to invasive disease by damaging respiratory epithelium, and COVID-19–associated pulmonary aspergillosis has been reported in a substantial proportion of patients with severe ARDS requiring intubation and is linked to higher mortality. Patients with chronic granulomatous disease are also at high risk, and A. nidulans is particularly associated with invasive infections in this group.
Pulmonary aspergillosis includes several clinical categories. Allergic fungal sinusitis occurs in patients with allergic rhinitis and is managed by sinus aeration and ensuring there is no tissue invasion, typically assessed by sinus CT. Allergic bronchopulmonary aspergillosis (ABPA) is a long-term allergic response seen most often in asthma and cystic fibrosis, driven by type I hypersensitivity and immune complex mechanisms, and it is commonly underdiagnosed. In ABPA, patients may develop worsening cough, wheeze, sputum production, and reduced pulmonary function; prevalence estimates range from about 1%–2% in persistently asthmatic patients and 2%–15% in cystic fibrosis. Chronic pulmonary aspergillosis is diagnosed when there are compatible thoracic imaging findings (preferably chest CT showing cavities with or without fungal ball or nodules), evidence of infection or immune response (such as elevated Aspergillus IgG/precipitins, strongly positive galactomannan or PCR), exclusion of alternative diagnoses, and symptoms or radiologic changes lasting at least 3 months.
Aspergillomas (“fungus balls”) occur when Aspergillus colonizes a preexisting lung cavity without tissue invasion or major immune response. These masses of hyphae usually develop in patients with underlying chronic lung disease such as prior tuberculosis, sarcoidosis, or emphysema. Many patients are asymptomatic, but hemoptysis is the most characteristic presentation, and imaging often shows an intracavitary mass with an air crescent that can move with patient position. Invasive aspergillosis is the most serious form and typically presents in immunocompromised patients as unremitting fever and new pulmonary infiltrates despite broad-spectrum antibiotics, along with dyspnea and nonproductive cough. Sudden pleuritic pain and tachycardia may mimic pulmonary embolism, and hemoptysis can occur. Imaging may show patchy bronchopneumonia, nodules, consolidation, cavitation, or characteristic CT findings such as the “halo sign” or “air-crescent sign.” In neutropenic hosts, incubation is often around 15 days. Invasive pulmonary aspergillosis is categorized as proven (sterile specimen with hyphae on microscopy or positive culture), probable (host factor plus clinical features plus mycologic evidence), or possible (host and clinical features without mycologic evidence).
Disseminated or extrapulmonary disease can occur in persistently immunosuppressed patients and may involve the brain, sinuses (with abscess formation by extension), gastrointestinal tract (ulcerations with risk of perforation or infarction), skin (necrotizing ulcers), bone (osteomyelitis), and even prosthetic or abnormal valves causing culture-negative endocarditis. Infections of implanted devices such as cardioverter-defibrillators have also been reported. Differential diagnoses vary by presentation and include tuberculosis, cystic fibrosis–related complications, lung carcinoma, eosinophilic pneumonia, bronchiectasis, sarcoidosis, and lung abscess.
Diagnosis depends on the clinical form. In ABPA, supportive laboratory features include peripheral eosinophilia, elevated total IgE, immediate skin test reactivity to Aspergillus, serum precipitins or IgG to A. fumigatus, and sometimes positive sputum cultures, though cultures are nonspecific. Diagnostic criteria commonly incorporate asthma or cystic fibrosis, evidence of immediate hypersensitivity or specific IgE, markedly elevated total IgE (often ≥1000 IU/mL, with some flexibility if other criteria are met), plus additional findings such as precipitins/IgG, radiographic opacities, or eosinophilia. In aspergilloma, sputum culture and serum precipitating antibodies may support the diagnosis, while imaging is often characteristic. In invasive aspergillosis, definitive diagnosis requires tissue invasion by septate, acute-angle branching hyphae or culture from tissue obtained via invasive sampling such as transbronchial biopsy. In high-risk patients, positive sputum or nasal cultures are strongly suggestive. Galactomannan antigen testing (Platelia Aspergillus ELISA) is widely used, especially in hematologic malignancy and stem-cell transplant populations; sensitivity may be reduced by ongoing antifungal therapy, and bronchoalveolar lavage galactomannan is often more sensitive than serum. Beta-D-glucan can detect early infection but is not specific for Aspergillus. Blood cultures are usually negative. PCR assays may be used in selected cases, but results should be interpreted alongside imaging, risk factors, and other mycologic data.
Imaging findings depend on the syndrome. ABPA may show fleeting patchy infiltrates, often in upper lobes, and many patients eventually develop central bronchiectasis. Aspergillomas are best seen on CXR or CT as an intracavity mass with an air crescent and may demonstrate movement with changes in patient positioning. In invasive disease, chest CT can reveal dense nodules that may cavitate, cavity formation, and the halo sign suggestive of angioinvasion, and CT is more sensitive than chest radiography in neutropenic patients.
Treatment is tailored to the specific form of aspergillosis. ABPA is treated with systemic corticosteroids such as prednisone (0.5–2 mg/kg/day orally) for 1–2 weeks followed by a slow taper over 2–3 months, combined with oral itraconazole (about 5 mg/kg/day up to 400 mg/day) with therapeutic drug monitoring for 3–6 months; voriconazole or posaconazole can be alternatives. Supportive care includes bronchodilators and physiotherapy, and serial chest imaging plus IgE levels can help track response. If prolonged steroids are needed, clinicians should consider prophylaxis against Pneumocystis jirovecii and strategies to preserve bone health.
Management of aspergilloma is challenging and sometimes controversial. Observation is reasonable for asymptomatic patients, and up to 10% may resolve without surgery or antifungals. For severe or life-threatening hemoptysis, surgical resection or arterial embolization is recommended. In patients at risk for major bleeding who have poor pulmonary reserve or are poor surgical candidates, antifungal therapy such as voriconazole may be considered, and in select cases intracavitary amphotericin B installation has been used. Resistance to itraconazole has increased in some Aspergillus strains, so local resistance patterns and prior azole exposure matter.
In invasive aspergillosis, first-line therapy is voriconazole (6 mg/kg IV/PO twice daily on day 1, then 4 mg/kg IV/PO twice daily), with therapeutic drug monitoring aiming for trough levels around 1.0–5.5 mg/L (often checked around day 4). Isavuconazonium sulfate (372 mg IV/PO three times daily for six doses, then 372 mg daily) and posaconazole (delayed-release tablets, suspension, or IV formulations with appropriate loading and maintenance regimens) are important alternatives, and posaconazole is also used for prophylaxis in selected high-risk groups such as neutropenic AML patients or those with graft-versus-host disease. Amphotericin B lipid complex or liposomal amphotericin B can be used as alternative therapy. Combination therapy may be considered in selected severe cases because azoles/polyenes target the cell membrane and echinocandins target the cell wall, but echinocandins should not be used as primary monotherapy for aspergillosis. Investigational agents such as olorofim and fosmanogepix are in clinical trials.
Special considerations include the high potential for drug–drug interactions with voriconazole, isavuconazole, and posaconazole, especially with chemotherapy and immunosuppressants, where azoles can raise drug levels and toxicity or alter efficacy. Azole resistance in A. fumigatus is an emerging concern, often related to CYP51A mutations; susceptibility testing should be considered in patients with substantial prior antifungal exposure or in areas with known high resistance rates. Hospital renovations and construction can increase airborne spores and infection risk in immunosuppressed patients. Coinfection with organisms such as Nocardia can occur, so persistent or atypical courses warrant broader evaluation. Referral to an infectious diseases specialist is recommended, particularly for invasive or disseminated disease, complex drug interactions, or refractory infections.
Aspergillosis is a group of illnesses caused by infection with Aspergillus species, a ubiquitous mold found worldwide in soil, building materials, and water. Humans are exposed mainly by inhaling airborne conidia (spores) that are small enough (about 2.5–3 μm) to reach the alveoli. Disease manifestations depend on the condition of the lungs, the host immune response, and the size of the inoculum. Aspergillus fumigatus is the most common human pathogen, while A. flavus is especially important in invasive disease and sinonasal involvement, and A. niger can also cause invasive infection. Hospital exposure can occur when unfiltered outside air enters through open windows or from contaminated water sources, and infections may also involve the nose, sinuses, external ear, or traumatized skin.
Risk is highest in immunocompromised patients, and invasive aspergillosis has become more common as modern therapies increasingly suppress immunity. Allogeneic stem cell transplant recipients and lung transplant recipients are among the highest-risk groups. A genetic deficiency of long pentraxin 3 (PTX3), which affects neutrophil antifungal function, may increase risk in hematopoietic stem-cell transplant patients. In advanced AIDS, patients with CD4 counts below 50/mm³ are more susceptible, although invasive aspergillosis remains otherwise uncommon in HIV. Severe influenza (including H1N1) can predispose to invasive disease by damaging respiratory epithelium, and COVID-19–associated pulmonary aspergillosis has been reported in a substantial proportion of patients with severe ARDS requiring intubation and is linked to higher mortality. Patients with chronic granulomatous disease are also at high risk, and A. nidulans is particularly associated with invasive infections in this group.
Pulmonary aspergillosis includes several clinical categories. Allergic fungal sinusitis occurs in patients with allergic rhinitis and is managed by sinus aeration and ensuring there is no tissue invasion, typically assessed by sinus CT. Allergic bronchopulmonary aspergillosis (ABPA) is a long-term allergic response seen most often in asthma and cystic fibrosis, driven by type I hypersensitivity and immune complex mechanisms, and it is commonly underdiagnosed. In ABPA, patients may develop worsening cough, wheeze, sputum production, and reduced pulmonary function; prevalence estimates range from about 1%–2% in persistently asthmatic patients and 2%–15% in cystic fibrosis. Chronic pulmonary aspergillosis is diagnosed when there are compatible thoracic imaging findings (preferably chest CT showing cavities with or without fungal ball or nodules), evidence of infection or immune response (such as elevated Aspergillus IgG/precipitins, strongly positive galactomannan or PCR), exclusion of alternative diagnoses, and symptoms or radiologic changes lasting at least 3 months.
Aspergillomas (“fungus balls”) occur when Aspergillus colonizes a preexisting lung cavity without tissue invasion or major immune response. These masses of hyphae usually develop in patients with underlying chronic lung disease such as prior tuberculosis, sarcoidosis, or emphysema. Many patients are asymptomatic, but hemoptysis is the most characteristic presentation, and imaging often shows an intracavitary mass with an air crescent that can move with patient position. Invasive aspergillosis is the most serious form and typically presents in immunocompromised patients as unremitting fever and new pulmonary infiltrates despite broad-spectrum antibiotics, along with dyspnea and nonproductive cough. Sudden pleuritic pain and tachycardia may mimic pulmonary embolism, and hemoptysis can occur. Imaging may show patchy bronchopneumonia, nodules, consolidation, cavitation, or characteristic CT findings such as the “halo sign” or “air-crescent sign.” In neutropenic hosts, incubation is often around 15 days. Invasive pulmonary aspergillosis is categorized as proven (sterile specimen with hyphae on microscopy or positive culture), probable (host factor plus clinical features plus mycologic evidence), or possible (host and clinical features without mycologic evidence).
Disseminated or extrapulmonary disease can occur in persistently immunosuppressed patients and may involve the brain, sinuses (with abscess formation by extension), gastrointestinal tract (ulcerations with risk of perforation or infarction), skin (necrotizing ulcers), bone (osteomyelitis), and even prosthetic or abnormal valves causing culture-negative endocarditis. Infections of implanted devices such as cardioverter-defibrillators have also been reported. Differential diagnoses vary by presentation and include tuberculosis, cystic fibrosis–related complications, lung carcinoma, eosinophilic pneumonia, bronchiectasis, sarcoidosis, and lung abscess.
Diagnosis depends on the clinical form. In ABPA, supportive laboratory features include peripheral eosinophilia, elevated total IgE, immediate skin test reactivity to Aspergillus, serum precipitins or IgG to A. fumigatus, and sometimes positive sputum cultures, though cultures are nonspecific. Diagnostic criteria commonly incorporate asthma or cystic fibrosis, evidence of immediate hypersensitivity or specific IgE, markedly elevated total IgE (often ≥1000 IU/mL, with some flexibility if other criteria are met), plus additional findings such as precipitins/IgG, radiographic opacities, or eosinophilia. In aspergilloma, sputum culture and serum precipitating antibodies may support the diagnosis, while imaging is often characteristic. In invasive aspergillosis, definitive diagnosis requires tissue invasion by septate, acute-angle branching hyphae or culture from tissue obtained via invasive sampling such as transbronchial biopsy. In high-risk patients, positive sputum or nasal cultures are strongly suggestive. Galactomannan antigen testing (Platelia Aspergillus ELISA) is widely used, especially in hematologic malignancy and stem-cell transplant populations; sensitivity may be reduced by ongoing antifungal therapy, and bronchoalveolar lavage galactomannan is often more sensitive than serum. Beta-D-glucan can detect early infection but is not specific for Aspergillus. Blood cultures are usually negative. PCR assays may be used in selected cases, but results should be interpreted alongside imaging, risk factors, and other mycologic data.
Imaging findings depend on the syndrome. ABPA may show fleeting patchy infiltrates, often in upper lobes, and many patients eventually develop central bronchiectasis. Aspergillomas are best seen on CXR or CT as an intracavity mass with an air crescent and may demonstrate movement with changes in patient positioning. In invasive disease, chest CT can reveal dense nodules that may cavitate, cavity formation, and the halo sign suggestive of angioinvasion, and CT is more sensitive than chest radiography in neutropenic patients.
Treatment is tailored to the specific form of aspergillosis. ABPA is treated with systemic corticosteroids such as prednisone (0.5–2 mg/kg/day orally) for 1–2 weeks followed by a slow taper over 2–3 months, combined with oral itraconazole (about 5 mg/kg/day up to 400 mg/day) with therapeutic drug monitoring for 3–6 months; voriconazole or posaconazole can be alternatives. Supportive care includes bronchodilators and physiotherapy, and serial chest imaging plus IgE levels can help track response. If prolonged steroids are needed, clinicians should consider prophylaxis against Pneumocystis jirovecii and strategies to preserve bone health.
Management of aspergilloma is challenging and sometimes controversial. Observation is reasonable for asymptomatic patients, and up to 10% may resolve without surgery or antifungals. For severe or life-threatening hemoptysis, surgical resection or arterial embolization is recommended. In patients at risk for major bleeding who have poor pulmonary reserve or are poor surgical candidates, antifungal therapy such as voriconazole may be considered, and in select cases intracavitary amphotericin B installation has been used. Resistance to itraconazole has increased in some Aspergillus strains, so local resistance patterns and prior azole exposure matter.
In invasive aspergillosis, first-line therapy is voriconazole (6 mg/kg IV/PO twice daily on day 1, then 4 mg/kg IV/PO twice daily), with therapeutic drug monitoring aiming for trough levels around 1.0–5.5 mg/L (often checked around day 4). Isavuconazonium sulfate (372 mg IV/PO three times daily for six doses, then 372 mg daily) and posaconazole (delayed-release tablets, suspension, or IV formulations with appropriate loading and maintenance regimens) are important alternatives, and posaconazole is also used for prophylaxis in selected high-risk groups such as neutropenic AML patients or those with graft-versus-host disease. Amphotericin B lipid complex or liposomal amphotericin B can be used as alternative therapy. Combination therapy may be considered in selected severe cases because azoles/polyenes target the cell membrane and echinocandins target the cell wall, but echinocandins should not be used as primary monotherapy for aspergillosis. Investigational agents such as olorofim and fosmanogepix are in clinical trials.
Special considerations include the high potential for drug–drug interactions with voriconazole, isavuconazole, and posaconazole, especially with chemotherapy and immunosuppressants, where azoles can raise drug levels and toxicity or alter efficacy. Azole resistance in A. fumigatus is an emerging concern, often related to CYP51A mutations; susceptibility testing should be considered in patients with substantial prior antifungal exposure or in areas with known high resistance rates. Hospital renovations and construction can increase airborne spores and infection risk in immunosuppressed patients. Coinfection with organisms such as Nocardia can occur, so persistent or atypical courses warrant broader evaluation. Referral to an infectious diseases specialist is recommended, particularly for invasive or disseminated disease, complex drug interactions, or refractory infections.
0 Comments
