Patients with hematological malignancies and recipients of allogeneic hematopoietic stem cell transplantation (allo-HSCT) as well as solid organ transplant recipients are the groups of patients with the highest risk of invasive fungal infections (IFI). Neutropenia, lymphopenia, chemotherapy of malignancies, radiation therapy, immunosuppressive therapy, administration of glucocorticosteroids, use of central venous catheters, dialysis therapy, liver and kidney failure, and diabetes are diseases and medical conditions which foster invasive fungal infections. In recent years, it has been observed that the most common etiological agents of these infections are yeast-like fungi of the genus Candida, and the second most common is moulds Aspergillus spp. Antifungal agent recommended for therapy of IFI caused by Aspergillus is voriconazole, according to the present guidelines. A combined therapy using voriconazole and caspofungin may not be effective. According to numerous publications, in case of infections caused by strains resistant to voriconazole, a therapeutic success is possible after a switch to the liposomal form of amphotericin B. Due to nonspecific clinical symptoms of IFI caused by Aspergillus spp., histopathological as well as mycological and serological tests, echocardiographic examination, magnetic resonance imaging (MRI) and computer tomography (CT) may contribute to an early and reliable diagnosis of invasive aspergillosis.
- Aspergillus fumigatus
- invasive fungal infection
- risk factors
- antifungal therapy
Transplant recipients constitute a group of patients who are immunocompromised. Among them, hematopoietic stem cell transplant (HSCT) recipients suffer from the most severe immunosuppression, which may be prolonged. Many risk factors make these patients prone to fungal infections caused by yeast-like fungi or molds.
Filamentous fungi of the genus
Aspergillosis may present in different forms, such as invasive aspergillosis (IA), allergic aspergillosis, chronic pulmonary aspergillosis, and as superficial disease in various anatomical locations (keratitis, otomycosis, and wound infections) [1, 4, 5, 6]. Allergic aspergillosis may present as allergic bronchopulmonary aspergillosis (ABPA) and allergic fungal rhinosinusitis (AFRS) .
Invasive aspergillosis is further divided into invasive pulmonary aspergillosis (IPA), sinusitis caused by
Invasive aspergillosis is the most common mold infection, particularly among immunocompromised patients. Patients subjected to allogeneic hematopoietic stem cell transplantation (alloHSCT) constitute a group of patients with the highest risk of systemic fungal infections, caused by both
2. Etiology of invasive aspergillosis
Aspergillosis is caused by opportunistic molds of the genus
The most common etiological agent of invasive aspergillosis with a high morality is
In clinical practice
3. Clinical forms of invasive aspergillosis
Molds of the genus
The spectrum of aspergillosis is determined by the host’s immune status (particularly severe and prolonged neutropenia) and the virulence of
Invasive aspergillosis is a life-threatening infection and a major cause of death in immunocompromised patients, particularly hematopoietic stem cell transplant recipients, but may be fatal even in immunocompetent individuals, with the death rate of 40% for pulmonary disease, 90% for disseminated disease, and practically 100% for disseminated disease with the central nervous system (CNS) involvement [1, 19]. According to the literature, invasive aspergillosis occurs in 1–15% of the solid organ transplant recipients, in whom mortality rates due to this disease range from 65 to 92% . However, currently these indices improve in these patients due to advances in immunosuppressive regimens and transplantation practices, as well as frequent use of antifungal prophylaxis.
Recent reports indicate that invasive aspergillosis is being increasingly diagnosed in patients without above-mentioned severe neutropenia—particularly in the lung transplant recipients, patients hospitalized in the intensive care unit or treated with corticosteroids [9, 11, 27]. Also, individuals with chronic obstructive pulmonary disease (COPD), liver failure, and other underlying diseases are listed in this group [8, 11, 20]. It has been reported that in ICU patients with invasive pulmonary aspergillosis 40–80% of them do not have any malignancy or other classical risk factors for this infection [8, 20]. Moreover, in contrast to patients with neutropenia, in ICU patients the symptoms of aspergillosis are atypical; therefore the diagnosis of this infection may be delayed or omitted, according to the autopsy studies [11, 15, 28]. Tejerina et al. showed that among 893 deceased patients, previously treated in ICU, only 40% (10 out of 25) had invasive aspergillosis diagnosed
3.1 Aspergillosis of the oral cavity and the upper respiratory tract
As mentioned earlier, aspergillosis affects mainly the lungs; however it may also be diagnosed in the upper respiratory tract and the oral cavity [2, 30]. Orofacial aspergillosis is relatively common in oncohematological patients undergoing chemotherapy .
Aspergillosis of the larynx is very rare, with only a few cases reported in the literature . Usually, it is secondary form of this disease, while primary aspergillosis of the larynx is even rarer. Risk factors for aspergillosis of the larynx comprise the use of inhaled or systemic steroids, prolonged antibiotic therapy, and underlying immunosuppression . It should be emphasized that these lesions may mimic malignancy or a premalignant condition, while proper diagnosis and administration of antifungal therapy, as well as elimination of the risk factors (if possible), are effective in the elimination of this condition .
It also appears that chronic tonsillitis may be caused by
In oral aspergillosis, the lesions are usually located on the palate or posterior tongue . They are yellow or black, with a necrotic ulcerated base. The hyphal elements of
3.2 Aspergillosis of the nose and paranasal sinuses
Paranasal sinuses may be colonized or infected by fungi, while infection can be invasive (acute or chronic) or noninvasive (allergic sinusitis and aspergilloma) . In invasive aspergillosis of the sinuses, there are rapid (within a few days) destructions of the sinuses, the nasal cavity, and the adjacent structures, such as the orbit and the brain 
It is estimated, that fungal sinusitis constitutes 6–9% of all cases of rhinosinusitis. Among fungi causing sinusitis, the most common is
The maxillary sinus is more often affected than other paranasal sinuses. However, it is frequently misdiagnosed, even as malignancy [3, 18, 34]. Untreated infection may spread to the other structures in the head . Invasive aspergillosis of the maxillary sinus should be considered in patients with maxillary sinusitis which does not respond to standard therapy with antibiotics, even in immunocompetent patients .
From the paranasal sinuses,
Factors which predispose immunocompetent individuals to fungal infections in the sinuses include polyps and blocked drainage of secretions . Additional risk factors for fungal sinusitis, including
Therapy of fungal sinusitis depends on its clinical form. In cases of
3.3 Aspergillosis of the lower respiratory tract
Within the lower respiratory tract,
The lungs are affected in up to 92% of all cases of invasive aspergillosis . Invasive pulmonary aspergillosis is a clinical entity characterized by invasion of the fungal hyphae into the blood vessels (angioinvasion), which subsequent hemoptysis. Other symptoms comprise nonproductive cough, pleuritic pain, low-grade fever, and dyspnea . However, in the early stages of the disease, both clinical symptoms and radiological findings may be nonspecific, so proper diagnosis and treatment may be delayed, resulting in increased mortality in this group of patients.
The frequency of invasive pulmonary aspergillosis has significantly increased in recent years due to a growing number of immunocompromised patients [8, 37]. This clinical entity most often occurs in patients with different forms of immunosuppression, for example, hematological malignancies, profound and prolonged neutropenia, or corticosteroid therapy, as well as organ transplantation, autoimmune and inflammatory conditions, in critically ill patients, and those with chronic obstructive pulmonary disease (COPD) [8, 37]. In about 50% of patients with invasive pulmonary aspergillosis, the infection spreads to other anatomical sites, such as the brain, liver, kidneys, or the gastrointestinal tract [8, 10, 13, 19, 25].
An uncommon clinical form of IA is an isolated invasive
Other forms of
As mentioned earlier, symptoms of the pulmonary disease may result not from actual infection, but allergic reaction of the host to the presence of
3.4 Aspergillosis of the central nervous system
Aspergillosis of the brain (cerebral aspergillosis) is usually a part of the disseminated disease after hematogenous spread of infection from the lungs, but rarely it may represent an isolated disease of the central nervous system (CNS) . It is reported in 10–15% of patients with invasive pulmonary aspergillosis . The most common risk factors comprise neutropenia and other forms of immunosuppression and transplantation surgery . Cerebral aspergillosis usually presents as a single or multiple brain abscess, also as cerebral vasculitis and cerebral infarcts, while meningitis is rare . Brain abscesses are common in HSCT recipients, while relatively rare in solid organ transplant (SOT) recipients [40, 41]. CT and MRI are recommended in patients in whom cerebral aspergillosis is suspected . Among all types of IA, brain aspergillosis has the worst prognosis, with mortality rate usually exceeding 90% (up to 100%), however early and proper treatment improves the prognosis in these patients and significantly increases their survival rates .
Aspergillosis of the CNS may also present as rhinocerebral aspergillosis, particularly in patients with underlying malignancies and neutropenia, HSCT recipients, and patients with diabetic ketoacidosis . Symptoms usually comprise fever, nasal or sinus congestion or pain, nasal discharge, unilateral facial swelling, and headaches . Necrotic lesions may be seen on the hard palate and in the nasal cavity. The spread of infection may lead to ophthalmic complications, such as ptosis, proptosis, and vision disturbances .
3.5 Invasive cardiac aspergillosis
Invasive cardiac aspergillosis may present as endocarditis, myocarditis, pericarditis, mediastinitis, septic thrombophlebitis, and infections of aortic grafts—also in transplant recipients [5, 6, 43, 44].
Endocarditis caused by
In the course of
Heart muscle may be affected by
3.6 Ocular aspergillosis
Aspergillosis of the eye may take a form of fungal keratitis, endophthalmitis, or invasive aspergillosis of the orbit. All structures of the eyeball may be affected—eyelids, conjunctivae, lacrimal apparatus, cornea, sclera, or uvea.
Fungal keratitis often presents as a corneal ulcer, which results from mechanical injury of the cornea, with subsequent necrosis. In a recent study, Manikandan et al. examined a total of 500 corneal scrapings, collected from patients in whom mycotic keratitis was suspected, out of which 68 (13.6%) were positive for
Endophthalmitis may be a complication of surgical procedures or may result from hematogenous spread from other sites of infection. Endogenous
Orbital invasive aspergillosis is a rare infection, which most often results from dissemination of the infection from the nose or paranasal sinuses. It may take an acute or chronic form. This form of IA usually presents with a severe orbital pain, paralysis of the oculomotor nerve and visual impairment. Ophthalmic complications, such as ptosis, proptosis, and vision disturbances may result from the spread of infection in rhinocerebral aspergillosis .
3.7 Aspergillosis of the genitourinary tract
Aspergillosis of the urinary tract is relatively rare. In immunocompromised patients, such as kidney transplant recipients, frequency of this form of aspergillosis amounts to only 0.5–2.2%, but is fatal in >88% of patients . Urinary tract aspergillosis may also be a complication of surgical procedures, such as lithotripsy, urinary tract instrumentation, or ureteric stenting, particularly in immunocompromised patients [62, 63, 64, 65]. Renal aspergillosis is being occasionally reported with obstruction of one or both ureters . Localized aspergillosis of the renal graft was reported in a child 5 months after kidney transplantation . A case of urinary tract aspergillosis presenting as an aspergilloma of the urinary bladder has also been described .
3.8 Other clinical forms of aspergillosis
Other clinical forms of aspergillosis—apart from above-mentioned—are very rare and comprise gastrointestinal aspergillosis, cutaneous aspergillosis,
Gastrointestinal aspergillosis is mainly reported in patients who are transplant recipients or severely malnourished . It results from ingestion of
Cutaneous aspergillosis is classified as primary or secondary . Primary form of the disease is usually reported in patients with burn wounds or surgical wounds. This clinical entity is caused by direct inoculation of the fungus or its spores into the injured skin . Primary cutaneous aspergillosis has been linked to leukemic patients, neonates, transplant recipients, as well as the use of occlusive dressings or permanent intravenous catheters . Secondary cutaneous aspergillosis results from hematogenous spread of the fungus and therefore represents a disseminated form of
Disseminated aspergillosis if defined as the involvement of at least two noncontiguous sites in the body, mainly in transplant recipients . Disseminated disease has been reported in 9–36% of kidney transplant recipients, 15–20% of lung transplant recipients, 20–35% of heart transplant recipients, and 50–60% of liver transplant recipients with invasive aspergillosis .
4. Aspergillosis in transplant recipients
In patients with immune deficiencies and other risk factors, invasive aspergillosis (IA) is a life-threatening infection caused by the opportunistic molds of the genus
In transplant recipients, particularly in hematopoietic stem cell transplant (HSCT) recipients who are severely immunocompromised, invasive aspergillosis is not only more common than in other groups of patients, but is also characterized by much more severe and rapidly progressive clinical course, and much higher mortality [12, 72].
Although prognosis has improved in recent years, IA still remains a significant post-transplant complication in solid organ transplant (SOT) recipients [43, 44]. It occurs in up to 30% of SOT recipients. Although in recent years the mortality rate in transplant recipients decreased from 65–92% to 22%, still an estimated 9.3–16.9% of all deaths in transplant recipients in the first year after transplantation can be attributed to IA .
The incidence of IA differs between different populations of transplant recipients, and unique risk factors for
Regarding the risk of invasive fungal infections (particularly IA) in transplant recipients, at present routine antifungal prophylaxis or preemptive therapy is recommended in HSCT recipients with prolonged neutropenia or graft-versus-host disease (GVHD), and in lung transplant recipients, while targeted prophylaxis should be considered in liver and heart transplant recipients [5, 6, 44, 71].
4.1 Hematopoietic stem cell transplant (HSCT) recipients
Invasive aspergillosis remains a major complication following allogeneic HSCT (alloHSCT) . The burden of IA has increased significantly in the last 30 years as a result of the increased number of patients undergoing immunosuppressive therapy for hematological malignancies and HSCT . It is estimated that IA is a leading cause of fatal outcomes in HSCT patients, accounting for 10% of all deaths in this group of patients .
In the recipients of alloHSCT, IA can occur during the neutropenic pre-engraftment phase (early IA) or during the post-engraftment period (late IA) . Although IA remains an important complication after allogeneic transplantation, regardless of the type of conditioning regimen, early IA is more common in patients undergoing myeloablative transplantation due to extensive chemotherapy and radiation used to destroy the native bone marrow, and prolonged neutropenia which results from this treatment [14, 74]. On the other hand, non-myeloablative HSCT comprises a shorter neutropenic period and therefore, a decrease in the incidence of early IA. However, a higher risk of GVHD in this group of patients and the therapies given for this condition caused a shift to late IA, diagnosed increasingly during the post-engraftment period . It should be noted that the risk period for late IA, associated with GVHD, can last for months to years, so prophylactic and monitoring procedures must be implemented over a long period. Carvalho-Dias et al. analyzed 24 cases of proven and probable invasive aspergillosis among HSCT recipients and reported, that 83% of the patients died due to invasive fungal infection within 60 days of follow-up .
Kojima et al. compared the incidence of IA and mortality rates due to this disease in 664 recipients of alloHSCT—486 conventional stem cell transplantation (CST) patients and 178 reduced-intensity stem cell transplant (RIST) recipients. The overall incidence of IA in all 664 recipients of alloHSCT was 35 (5.3%) . Despite significant differences in the estimated 3-year incidence of IA in CST group (4.5%) and RIST population (8.2%) (P = 0.045), the mortality rates were similar in both groups (76 and 86%, respectively). However, the median onset of IA after RIST was day 127, which was significantly later than that after CST—day 97 . Furthermore, a multivariate analysis showed that IA was associated with age > 50 years and the presence of acute or chronic GVHD . In another study, Labbe et al. analyzed the risk factors for IA in 125 alloHSCT recipients with nonmyeloablative (NMA) regimens, who received a 6/6 matched sibling NMA HSCT and were treated homogenously . IA developed in 13 patients (5 proved, 6 probable, and 2 possible IA), at 44–791 days (median 229 days) after NMA HSCT. The risk of IA was calculated as 7% at 1 year, 11% at 2 years, and 15% at 3 years after NMA alloHSCT . It was concluded that in NMA HSCT recipients the risk of IA increases over time and is significantly associated with intestinal GVHD, therefore these patients should be monitored for this complication and administration of antifungal prophylaxis with activity against molds should be considered .
4.2 Lung and heart-lung transplant recipients
In lung transplant recipients, invasive aspergillosis is the predominant fungal infection [44, 71, 75]. In the past, the incidence of IA in this group of patients was reported in the range of 4.0–23.3%, however, newer studies point to a lower frequency of this disease . On the other hand, the time from lung transplantation to the onset of IA becomes longer due to the use of antifungal prophylaxis in the early post-transplant period. Therefore the median time to IA onset has increased from 120 days post-transplant to 483 or 508 days post-transplant reported in recent studies .
The most common species linked to the etiology of IA in lung transplant recipients is
The significance of the patient’s airway colonization with
It should be beared in mind that in lung transplant recipients there is a continuous exposure of the graft to the external environment through the airways, with impaired defense mechanisms (decreased mucociliary function, weakened cough reflex) in the early postransplant period .
In lung transplant recipients, there is a transient devascularization of the bronchial anastomotic site, which may contribute to ischemic injury and necrosis. This is a risk factor for development of ulcerative tracheobronchitis—a locally invasive form of IA involving the anastomotic site, the trachea, and the bronchi [44, 78]. In these patients, bronchovascular fistulas may develop, with a potentially fatal hemorrhage.
In the literature reports, the mortality rate of lung transplant recipients with IA ranges from 23 to 29% in individuals with tracheobronchitis to as high as 67–82% in patients with invasive pulmonary aspergillosis, but according to some estimates at present, it could be as low as 20% . In a follow-up study of 251 lung transplant recipients,
4.3 Heart transplant recipients
According to the literature, the incidence of invasive aspergillosis in heart transplant recipients ranges from 1 to 14% [44, 79]. In this population, the risk factors for IA comprise isolation of
Invasive pulmonary aspergillosis remains the most common clinical presentation of this disease, particularly in early-onset IA (≤3 months after transplantation), while in late-onset IA, there is a higher frequency of disseminated disease and involvement of the central nervous system and other extrapulmonary sites [79, 80]. In an analysis of 455 heart transplant recipients, in whom 8 cases of IA have been diagnosed, all had invasive pulmonary form of the disease . Risk factors for early-onset IA (within ≤3 months after heart transplantation), comprised hemodialysis, thoracic reoperation, and the presence of another case in the institution within the preceding 3 months . For late-onset IA in this population of heart transplant recipients, hemodialysis and augmented immunosuppression were identified as risk factors . In the clinical course of these cases, predominated septic shock and multiple organ dysfunction syndrome (MODS), nonspecific clinical and radiographic findings, as well as rapid (at a median of 11 days after diagnosis) mortality despite administration of antifungal therapy with activity against molds . In a study by Montoya et al., none of the heart transplant recipients with either invasive pulmonary aspergillosis or invasive extrapulmonary aspergillosis had neutropenia . Therefore, even in the absence of neutropenia invasive pulmonary aspergillosis should be suspected, particularly within the first 3 months of transplantation in heart transplant recipients who have fever and respiratory symptoms, a positive result of culture of respiratory secretions, and abnormal radiological findings (particularly nodules) .
A study of 479 consecutive heart transplant recipients in a single institution revealed a decrease in the incidence of IA from 8.7% (24/277) in the period 1988–2000 to 3.5% (7/202) in 2001–2011 . Overall the incidence of IA in the studied group of heart transplant recipients was 6.5% (31 of 479). However, the authors report that four of seven cases were diagnosed as an outbreak, which indicates that favorable conditions for an infection with
4.4 Liver transplant recipients
Invasive aspergillosis is reported in 1.0–9.2% of the liver transplant recipients. Mortality rates have decreased from 83–88% in earlier studies to 33–65% in more recent reports . However, they remain very high in patients who develop invasive aspergillosis after liver retransplantation (82.4%), particularly in those undergoing surgery later than 30 days after primary liver transplantation (100%) .
Risk factors for invasive fungal infections, including aspergillosis, in these patients, comprise retransplantation (30-fold higher risk) and renal dysfunction, particularly requiring any form of renal replacement therapy (15- to 25-fold higher risk) . Furthermore, transplantation for fulminant hepatic failure, pretransplant corticosteroid therapy, cytomegalovirus (CMV) infection, and prolonged intensive unit care stay are other risk factors associated with invasive aspergillosis in liver transplant recipients . It is underlined that liver transplant recipients are particularly susceptible to disseminated and central nervous system invasive aspergillosis .
Previously most invasive fungal infections in liver transplant recipients occurred within the first month after transplantation (the median time to onset was reported as 16–17 days), however, in recent years, they are usually diagnosed in the late period (>90 days) after liver transplantation. After renal replacement therapy and retransplantation, the median time to onset of IA was reported as 13 and 28 days, respectively .
4.5 Kidney transplant recipients
Invasive aspergillosis has been reported in 0.7–4.0% of the renal transplant recipients . It should be emphasized that despite a relatively low overall incidence of IA in comparison to other solid organ transplant (SOT) recipients, the mortality rate is high in these patients—in the range of 67–75% . Risk factors for invasive aspergillosis in kidney transplant recipients are the following: potent immunosuppressive therapy, leukopenia, prolonged and/or high dose corticosteroid therapy, longer duration of renal replacement therapy in the pretransplant period, and graft failure requiring hemodialysis [44, 82].
In a recent study, Desbois et al. analyzed the outcome of IA in kidney transplant recipients in the era of voriconazole availability . Unfortunately, they concluded that the prognosis of patients with IA after renal transplantation is still poor, and even if the patients survive, the risk of graft loss is high .
5. Mycological diagnostics
The diagnosis of invasive aspergillosis remains a significant challenge . It is usually based on a histopathological evidence of tissue invasion, in conjunction with an isolation of
It should be emphasized that fast detection and identification of the etiological agent of infection is of utmost importance as it allows an early start of an effective antimicrobial therapy, which improves the patient’s chances to survive.
In mycological diagnostics, the culture of the fungus from the site of infection and
Blood cultures are rarely positive in patients with invasive pulmonary aspergillosis [8, 19, 45]. In patients with pulmonary aspergillosis,
In laboratory diagnostics of this form of aspergillosis, detection of
Laboratory methods currently used in diagnosis of invasive aspergillosis comprise three groups of techniques: detection of fungal invasion in histopathological examination of tissue sections; direct microscopy and isolation of
5.1 Histopathological examination of tissue sections
Histopathological examination of biopsy or autopsy tissue sections confirms the fungal etiology of invasive infections [1, 5, 6, 13, 15, 19]. Tissue sections are usually stained with hematoxylin and eosin, but other staining techniques are also used in practice (e.g. Gomori-Grocott methenamine silver stain, periodic acid-Schiff stain) [2, 88, 89]. Histopathological tissue sections from a patient with invasive easpergillosis of the heart and lung are shown in Sulik-Tyszka et al. .
In tissue sections,
5.2 Direct microscopic examination, culture, and identification of
Clinical samples for isolation of
The direct microscopic examination allows not only rapid detection of the fungus directly in the specimen, but also its preliminary identification.
A universal solid medium for culturing fungi is Sabouraud agar. When culturing a sample obtained from a site which is primarily nonsterile, Sabouraud agar supplemented with chloramphenicol and gentamicin is used. Czapek-Dox agar and 2% malt extract agar are also used, as well as liquid media . Commercially available media are recommended in order to standardize the culture methods.
Identification of the isolates belonging to the genus
Interpretation of the mycological culture results is important and depends on the clinical picture . In a routine microbiology laboratory work, most of the isolates of
It should be emphasized that in transplant recipient’s fungal cultures may be negative, despite disseminated infection, and in invasive aspergillosis, blood cultures are usually negative, even in patients with
5.3 Serological testing in the diagnosis of aspergillosis
Serological tests are widely used in the laboratory diagnostics of aspergillosis. Conventional methods, such as culture of clinical samples and direct microscopy of the specimens, have low sensitivity and may give positive results in the late stages of the disease . Furthermore, suitable specimens for these methods may be difficult to obtain in severely ill, immunocompromised patients. In recent years, serological techniques are being used increasingly on such specimens, like serum or BALF, for detection of fungal antigens (e.g. galactomannan, (1,3)-ß-d-glucan) and anti-galactomannan antibodies against
Duration of antifungal therapy may be guided not only by monitoring of galactomannan levels, but also by the clinical status of the patient and radiological findings.
5.3.1 Galactomannan (GM)
Galactomannan (GM) is a cell wall component of
Galactomannan concentration in the bronchoalveolar lavage fluid, in combination with other diagnostic tests (e.g. chest CT scan or mycological culture) is recommended as a test for the diagnosis of IA in lung and nonlung transplant recipients . Galactomannan in BALF sample has proven superior to serum testing with high sensitivity (67–100%) and specificity rates (91–100%) for the diagnosis of invasive aspergillosis in lung transplant recipients . In patients with prolonged neutropenia and allogeneic stem cell transplant recipients during the early engraftment phase, GM detection is commonly used, and serial screening for GM in serum has a high sensitivity and a negative predictive value for IA [13, 14]. However, serial screening for GM is not recommended in patients receiving antifungal prophylaxis with anti-
False-positive results of galactomannan detection have been documented in up to 13–29% of the liver transplant recipients and in 20% of the lung transplant recipients . In the liver transplant recipients, false-positive results of galactomannan tests were more often seen in patients with transplantation for autoimmune liver disease, perioperative prophylaxis with β-lactam antibiotics, and requirement of dialysis. Most false-positive tests after lung transplantation occurred in the early post-transplant period: that is, in 43% within 3 days, in 64% within 7 days, and in 79% within 14 days of surgery. False-positive results of galactomannan detection are linked to several factors, such as antibiotic therapy with specific groups of antibacterials (such as some cephalosporins, carbapenems, amoxicillin-clavulanate, ampicillin/sulbactam, and piperacillin/tazobactam), cyclophosphamide therapy, as well as administration of blood products, albumin or immunoglobulins, or the use of cellulose hemodialysis membranes [93, 94].
Detection of (1,3)-ß-d-glucan is a nonspecific test for fungal infection, as it is one of the main cell wall polysaccharide components of many fungi . Available diagnostic tests are characterized by a high sensitivity and specificity and enable detection of (1,3)-ß-d-glucan at the concentration of >1 pg/ml. It has been reported that in living-donor, liver allograft recipients, detection of (1,3)-ß-d-glucan was useful for the diagnosis of invasive aspergillosis . Several factors have been linked to false-positive results of the tests for (1,3)-ß-d-glucan, which are similar to those for galactomannan detection .
5.4 Molecular methods
At present, molecular diagnostic tests for
The majority of molecular methods which can be used in the clinical microbiology laboratories are based on PCR technique. These methods are particularly useful for testing of lung specimens. It has been reported, that quantitative PCR test used for diagnosis of IA with a sample of bronchoalveolar lavage fluid was characterized by 67% sensitivity and 100% specificity . Perhaps in the future, quantitative PCR tests will also be used to monitor the response to antifungal treatment in patients with IA .
Fluorescence in situ hybridization-based molecular method is a promising approach in the
6. Treatment of invasive aspergillosis
Successful treatment of invasive aspergillosis comprises early diagnosis of the disease, selection of an appropriate antifungal agent active against fungi of the genus
At present, there are three groups of antifungal agents, which can be used in the therapy of aspergillosis: azoles, polyenes, and echinocandins . The choice of treatment regimen depends on several factors, including the host’s immune status, liver, and kidney functions, and prior antifungal therapies . Treatment regimens of invasive aspergillosis are shown in Figure 2.
It should be emphasized that in the choice of proper antifungal therapy, susceptibility testing of the cultured isolate is important in view of an emerging resistance of some
Apart from antifungal therapy, surgery may be indicated in patients with invasive aspergillosis. It applies to the cases in which the disease is localized and infection site is easily accessible to debridement (e.g. invasive fungal sinusitis or localized cutaneous lesions) [5, 6]. Surgical excision or debridement may be used for both diagnostic and therapeutic purposes .
Surgery of the sinuses may involve removal of the granulation tissue and necrotic bone . Surgery may also be required in patients with endocarditis, osteomyelitis, or focal lesions in the central nervous system [5, 6]. Surgery is particularly indicated for persistent, or a life-threatening hemoptysis, lesions in the proximity of great vessels or pericardium, nasal and sinus infections, single cavitary lesion in the lung, intracranial abscesses, as well as lesions invading the pericardium, bone, the subcutaneous, or thoracic tissue .
According to the newest guidelines of ECIL-6 (the European Conference on Infections in Leukemia), recommendations of Infectious Diseases Society of America (IDSA) and European Society of Clinical Microbiology and Infectious Diseases, European Confederation of Medical Mycology, European Respiratory Society (ESCMID/ECMM/ERS) as well as expert groups, the drugs of first choice in therapy of invasive aspergillosis are triazoles—voriconazole or isavuconazole in monotherapy [5, 6, 13, 20, 71].
Isavuconazole is as effective as voriconazole, and in addition, it is characterized by a better safety profile, therefore in the newest guidelines, it has been granted AI recommendation equally with voriconazole [5, 6]. In patients who do not tolerate voriconazole, therapy with itraconazole or posaconazole may be considered; however, cross-resistance between azoles may be a problem . An alternative antifungal agent used in the therapy of this disease is liposomal amphotericin B [5, 6, 13, 71]. It is emphasized that the chosen agent should be implemented as quickly as possible after fungal etiology of the infection has been suspected [5, 15]. At present, the routine use of combination therapy is neither recommended as a first line treatment, nor the use of echinocandins as the primary treatment .
In recent years, an increase in the percentage of strains of
Voriconazole has emerged as the preferred agent for primary therapy of IA. Its efficacy has been confirmed in many studies, including hematopoietic stem cell transplant recipients and patients with hematological malignancies, as well as SOT recipients . Voriconazole was effective in heart transplant recipients, in SOT recipients with central nervous system aspergillosis. In a lung transplant patient with
6.2 Liposomal amphotericin B
An alternative antifungal agent recommended in therapy of IA is liposomal amphotericin B (L-AmB), which is active
Echinocandins (caspofungin, micafungin, or anidulafungin) are not recommended as first-line therapy of invasive aspergillosis, as they exhibit only fungistatic (not fungicidal) activity against the isolates of
6.4 Salvage therapy
In patients not responding to monotherapy with antifungal agents recommended as first-line therapy, such as voriconazole, isavuconazole, or liposomal amphotericin B, a salvage therapy must be considered, with the use of a combination antifungal regimen . In these cases, it is suggested to combine an echinocandin (caspofungin, micafungin, or anidulafungin) with voriconazole, isavuconazole, or liposomal amphotericin B, while there are no clinical data to support the use of triazoles in combination with amphotericin B . Apart from salvage antifungal therapy, reduction of the doses of immunosuppressive agents (if feasible), as well as surgery should be considered in these patients.
6.5 Duration of antifungal therapy
The duration of therapy for IA is usually 12 weeks, but may range from 3 to >50 weeks or may be even lifelong [5, 6, 13, 44]. Many factors may influence it, such as the response to administered therapy, the patient’s immune status and underlying diseases . It is recommended to continue therapy until all clinical and radiographic abnormalities have resolved, and cultures are negative for
6.6 Prophylaxis of invasive aspergillosis in transplant recipients
Antifungal prophylaxis against aspergillosis should be used in patients at high risk of IA during prolonged neutropenia [5, 6]. It is recommended to administer posaconazole, voriconazole, or micafungin (caspofungin is also probably effective) [5, 6]. Prophylaxis with itraconazole is effective, but absorption and tolerability of this drug may be a problem.
For allogeneic HSCT recipients with graft-versus-host disease (GVHD), who are at high risk for IA, prophylaxis with posaconazole is recommended, but other azoles active against
According to the ECIL-6 and other recommendations, antifungal prophylaxis with either a systemic triazole (voriconazole or itraconazole) or an inhaled AmB product is recommended for 3–4 months after lung transplantation [5, 6]. Aerosolized amphotericin B is an option which allows the direct administration of the antifungal agent into the transplanted lung, with avoidance of systemic unwanted effects and drug–drug interactions . However, for certain groups of lung transplant recipients (single lung transplant recipients, mold colonization before or after lung transplantation, mold infections detected in explanted lungs, and fungal infections of the sinus) systemic voriconazole or itraconazole is recommended rather than inhaled AmB. Patterson et al. and other experts recommend reinitiation of antifungal prophylaxis in lung transplant recipients who receive immunosuppression augmentation with thymoglobulin, alemtuzumab, or high-dose corticosteroids [5, 6].
For other SOT recipients, antifungal prophylaxis against IA is not routinely recommended and should be based on the institutional epidemiology of aspergillosis and assessment of the patient’s risk factors [5, 6, 44]. A common approach to antifungal prophylaxis in liver transplant recipients is to target high-risk patients (fulminant hepatic failure, reoperation, retransplantation, or with renal failure), and it is administered during pre-transplant hospitalization and for the first-month posttransplant. Risk factors for IA have also been identified in heart transplant recipients, such as pretransplant colonization with
6.7 Immunomodulatory agents and new therapeutic options
At present, it is recommended to reduce the doses of immunosuppressive therapy administered to the patient (or eliminate it, if possible), as this improves the outcome of anti-
A relatively new approach to the therapy of invasive aspergillosis in immunocompromised patients involves the use of immunomodulatory agents which would enhance the host’s immune system . There is a potential for clinical use of selected cytokines or colony-stimulating factors (e.g. granulocyte colony-stimulating factor, G-CSF; granulocyte-macrophage colony-stimulating factor, GM-CSF; interferon-γ) with immunomodulatory effect [44, 110].
There is an ongoing search for new, more effective antifungals, which will be active also against drug-resistant isolates of
Diagnosis of invasive aspergillosis remains a challenge for clinicians and microbiologists. Progress in modern diagnostic methods and imaging techniques may contribute to an early and reliable diagnosis of infections caused by