Prospective surveillance for invasive fungal infections in hematopoietic stem cell transplant recipients, 2001-2006: overview of the Transplant-Associated Infection Surveillance Network (TRANSNET) Database

Current status of antifungal resistance and its impact on clinical practice

Mortality linked to invasive fungal diseases remains very high despite the availability of novel antifungals and new therapeutic strategies. Candida albicans and Aspergillus fumigatus account for most invasive mycosis produced by yeast or moulds, respectively. Other Candida non-albicans are increasingly being reported and newly emerging, as well as cryptic, filamentous fungi often cause disseminated infections in immunocompromised hosts. Management of invasive fungal infections is becoming a challenge as emerging fungal pathogens generally show poor response to many antifungals. The ability of reference antifungal susceptibility testing methods to detect emerging resistance patterns, together with the molecular characterization of antifungal resistance mechanisms, are providing useful information to optimize the effectiveness of antifungal therapy. The current status of antifungal resistance epidemiology with special emphasis on the molecular resistant mechanisms that have been described in the main pathogenic fungal species are reviewed.

Nonmolecular methods for the diagnosis of respiratory fungal infections

Diagnosis of invasive fungal pneumonias by conventional culture methods is difficult to assess and often delayed. Nonmolecular fungal markers have emerged as an important adjunctive tool to support their diagnosis in combination with other clinical, radiologic, and microbiological criteria of invasive fungal diseases. Concerns about the sensitivity and specificity of some tests in different patient populations should lead to warnings about their widespread use. None can identify the emerging and particularly deadly fungal pathogens responsible for mucormycosis. The role of nonmolecular fungal markers should be better defined in combination with other microbiological and radiologic tools in preemptive antifungal strategies.

Increased incidence of invasive fusariosis with cutaneous portal of entry, Brazil

Most cases of infection with Fusarium spp. fungi involved primary skin lesions.

Invasive fusariosis (IF) is an infection with Fusarium spp. fungi that primarily affects patients with hematologic malignancies and hematopoietic cell transplant recipients. A cutaneous portal of entry is occasionally reported. We reviewed all cases of IF in Brazil during 2000–2010, divided into 2 periods: 2000–2005 (period 1) and 2006–2010 (period 2). We calculated incidence rates of IF and of superficial infections with Fusarium spp. fungi identified in patients at a dermatology outpatient unit. IF incidence for periods 1 and 2 was 0.86 cases versus 10.23 cases per 1,000 admissions (p<0.001), respectively; superficial fusarial infection incidence was 7.23 versus 16.26 positive cultures per 1,000 superficial cultures (p<0.001), respectively. Of 21 cases of IF, 14 showed a primary cutaneous portal of entry. Further studies are needed to identify reservoirs of these fungi in the community and to implement preventive measures for patients at risk.

Immunosuppressive compounds exhibit particular effects on functional properties of human anti-Aspergillus Th1 cells

Allogeneic hematopoietic stem cell transplant (HSCT) recipients are at high risk for invasive aspergillosis. Whereas adoptive immunotherapy transferring donor-derived anti-Aspergillus TH1 cells has been shown to be beneficial for HSCT recipients suffering from invasive aspergillosis, little is known about the impact of commonly used immunosuppressants on the functional properties of anti-Aspergillus TH1 cells. Anti-Aspergillus TH1 cells were coincubated with different concentrations of methylprednisolone, cyclosporine (CsA), mycophenolic acid (MPA), the active component of mycophenolate mofetil, and rapamycin. Immunosuppressants were tested in concentrations reflecting common target levels in serum and in significantly lower and higher concentrations. Apoptosis of anti-Aspergillus TH1 cells, as well as proliferation and production of gamma interferon (IFN-γ) and CD154 upon restimulation, was evaluated in the presence and absence of immunosuppressive compounds. All dosages of CsA, MPA, and methylprednisolone significantly decreased the number of viable anti-Aspergillus TH1 cells in the cell culture, which was due partly to an impaired proliferative capacity of the cells and partly to an increased rate of apoptosis. In addition, CsA significantly decreased the number of IFN-γ-producing cells and had the highest impact of all immunosuppressants on IFN-γ levels in the supernatant. CsA also significantly decreased the expression of CD154 by anti-Aspergillus TH1 cells. Variant dosages of immunosuppressants exhibit particular effects on essential functional properties of anti-Aspergillus TH1 cells. Our findings may have an important impact on the design of clinical trials evaluating the therapeutic benefit of anti-Aspergillus TH1 cells in allogeneic HSCT recipients suffering from invasive aspergillosis.

Clinical utility of Aspergillus galactomannan and PCR in bronchoalveolar lavage fluid for the diagnosis of invasive pulmonary aspergillosis in patients with haematological malignancies

Interpretation of Aspergillus galactomannan (GM) and PCR results in bronchoalveolar lavage (BAL) fluid for the diagnosis of invasive pulmonary aspergillosis (IPA) in patients with haematological malignancies requires clarification. A total of 116 patients underwent BAL for investigation of new lung infiltrates: 40% were neutropenic, 68% and 36% were receiving mould-active antifungal agents and β-lactam antibiotics. The diagnosis of proven IPA (n = 3), probable IPA (n = 15), and possible invasive fungal disease (IFD, n = 50) was made without inclusion of GM results. BAL GM (at cut-off of 0.8) had lower diagnostic sensitivity for IPA than PCR (61% versus 78%) but higher specificity (93% versus 79%). Both tests had excellent negative predictive values (85-90%), supporting their utility in excluding IPA. The use of BAL GM and PCR results increased the certainty of Aspergillus aetiology in 7 probable IPA cases where fungal hyphae were detected in respiratory samples by microscopy, and upgraded 24 patients from possible IFD to probable IPA. Use of BAL GM and PCR improves the diagnosis of IPA.

Performance of galactomannan, beta-d-glucan, Aspergillus lateral-flow device, conventional culture, and PCR tests with bronchoalveolar lavage fluid for diagnosis of invasive pulmonary aspergillosis

Galactomannan detection in bronchoalveolar lavage (BAL) fluid samples (GM test) is currently considered the gold standard test for diagnosing invasive pulmonary aspergillosis (IPA). The limitations, however, are the various turnaround times and availability of testing. We compared the performance of GM testing with that of conventional culture, an Aspergillus lateral-flow-device (LFD) test, a beta-d-glucan (BDG) test, and an Aspergillus PCR assay by using BAL fluid samples from immunocompromised patients. A total of 78 BAL fluid samples from 78 patients at risk for IPA (74 samples from Graz and 4 from Mannheim) collected between December 2012 and May 2013 at two university hospitals in Austria and Germany were included. Three patients had proven IPA, 14 probable IPA, and 17 possible IPA, and 44 patients had no IPA. The diagnostic accuracies of the different methods for probable/proven IPA were evaluated. The diagnostic odds ratios were the highest for the GM, PCR, and LFD tests. The sensitivities for the four methods (except culture) were between 70 and 88%. The combination of the GM (cutoff optical density index [ODI], >1.0) and LFD tests increased the sensitivity to 94%, while the combination of the GM test (>1.0) and PCR resulted in 100% sensitivity (specificity for probable/proven IPA, 95 to 98%). The performance of conventional culture was limited by low sensitivity, while that of the BDG test was limited by low specificity. We evaluated established and novel diagnostic methods for IPA and found that the Aspergillus PCR, LFD, and GM tests were the most useful methods for diagnosing the disease by using BAL fluid samples. In particular, the combination of the GM test and PCR or, if PCR is not available, the LFD test, allows for sensitive and specific diagnosis of IPA.

Neutropenia and invasive fungal infection in patients with hematological malignancies treated with chemotherapy: a multicenter, prospective, non-interventional study in China

In this study, we explored the relationship between neutropenia (absolute neutrophil count (ANC) <1,500/mm(3)) and invasive fungal infection (IFI) in Chinese patients who had hematological malignancies treated with chemotherapy. We conducted a multicenter, prospective, non-interventional study of consecutive patients with hematological malignancies undergoing chemotherapy in China and determined clinical characteristics of patients who developed neutropenia and IFI. The results indicated that for the 2,177 neutropenic patients, 88 (4.0 %) were diagnosed with IFI. We found that a high risk of IFI (P<0.05) is associated with male gender, non-remission of the primary disease, use of two or more broad-spectrum antibiotics, treatment with parenteral nutrition, presence of cardiovascular disease, history of IFI, and neutropenia. When the ANC was less than 1,000, 1,000∼500, 500∼100, and <100/mm(3), the incidence of IFI was 0.5, 5.2, 3.9, and 4.7 %, respectively (ANC>1,000/mm(3) versus other groups, P<0.001). When the ANC was less than 1,000, 500, or 100/mm(3) for 10 days or more, the incidence of IFI was 3.2 versus 6.1 % (P=0.0052), 3.5 versus 7.1 % (P=0.0021), and 3.1 versus 10.0 % (P<0.001). When the ANC was less than 100/mm(3), taking antifungal prophylaxis reduced the incidence of IFI (P<0.05). The IFI-attributable mortality rate was 11.7 %. In conclusion, Chinese patients with IFI, severe and prolonged neutropenia increases the incidence of IFI. The incidence of IFI associated with neutropenia was reduced when antifungal prophylaxis was given. IFI was associated with a significantly increased high mortality rate in hematological malignancy patients with neutropenia.

The Prospective Antifungal Therapy Alliance(®) registry: A two-centre Canadian experience

BACKGROUND

The Prospective Antifungal Therapy Alliance(®) registry is a prospective surveillance study that collected data on the diagnosis, management and outcomes of invasive fungal infections (IFIs) from 25 centres in North America from 2004 to 2008.

OBJECTIVE

To evaluate surveillance data on IFIs obtained from study centres located in Canada.

METHODS

Patients with proven or probable IFIs at two Canadian medical centres were enrolled in the registry. Information regarding patient demographics, fungal species, infection sites, diagnosis techniques, therapy and survival were analyzed.

RESULTS

A total of 347 patients from Canada with documented IFIs were enrolled in the Prospective Antifungal Therapy Alliance registry. Infections occurred most commonly in general medicine (71.8%), nontransplant surgery (32.6%) and patients with hematological malignancies (21.0%). There were 287 proven IFIs, including 248 Candida infections. Forty-six patients had invasive aspergillosis (IA); all of these were probable infections. Most cases of invasive candidiasis were confirmed using blood culture (90.5%), while IA was most frequently diagnosed using computed tomography scan (82.6%) and serological methods (82.6%). Fluconazole was the most common therapy used for Candida infections, followed by the echinocandins. Voriconazole therapy was most commonly prescribed for IA.

CONCLUSIONS

The present study demonstrated that general medicine, surgery and hematological malignancy patients in Canada are susceptible to developing IFIs. In contrast to the United States, Candida albicans remains responsible for most IFIs in these Canadian centres. Surrogate serum markers are commonly being used for the diagnosis of IA, while therapy for both IFIs has shifted to broader-spectrum azoles and echinocandins.

Clinical characteristics and outcomes in 303 HIV-infected patients with invasive fungal infections: data from the Prospective Antifungal Therapy Alliance registry, a multicenter, observational study

This analysis aimed to characterize the epidemiology, diagnosis, treatment, and outcomes of invasive fungal infections (IFIs) in patients with human immunodeficiency virus (HIV). Data were examined for HIV patients enrolled in the Prospective Antifungal Therapy (PATH) Alliance registry, a multicenter, observational study of patients with IFIs in North America from 2004 to 2008. Patient demographics, clinical characteristics, comorbidities, antifungal therapies, and survival were assessed. In total, 320 fungal isolates were identified from 303 HIV patients with IFIs in the PATH Alliance® registry. These included Cryptococcus (50.0%), Candida (33.1%), Histoplasma (9.1%), and Aspergillus (4.4%). Candida infection occurred mainly as candidemia (86.0%); Cryptococcus as central nervous system infection (76.7%); Histoplasma as disseminated infection (74.1%); and Aspergillus as pulmonary infection (81.8%). The CD4 cell count was ≤200 cells/μL in 91.2% of patients with available data. The majority of patients with Cryptococcus (77.9%), Histoplasma (100.0%), and Aspergillus (71.4%) infections had CD4 cell counts <50 cells/μL compared with 48.9% of patients with Candida infections. Patients with candidiasis were more likely to have other conditions requiring medical services compared with patients with other IFIs. Survival probability was lower in patients with Aspergillus (0.58) and Candida (0.59) infection than in patients with Histoplasma (0.84) and Cryptococcus (0.81) infection. In the highly active antiretroviral therapy era, traditional opportunistic IFIs such as cryptococcosis and histoplasmosis still mainly occur in HIV patients with CD4 counts <50 cells/μL. Fungal infections remain a clinical challenge in HIV patients with severe immunosuppression. Our data also suggest that HIV patients with CD4 cell counts >200 cells/μL and other underlying conditions may be susceptible to invasive candidiasis.

Biology, systematics, and clinical manifestations of Zygomycota infections

Fungi cause opportunistic, nosocomial, and community-acquired infections. Among fungal infections (mycoses) zygomycoses are exceptionally severe, with a mortality rate exceeding 50%. Immunocompromised hosts, transplant recipients, and diabetic patients with uncontrolled keto-acidosis and high iron serum levels are at risk. Zygomycota are capable of infecting hosts immune to other filamentous fungi. The infection often follows a progressive pattern, with angioinvasion and metastases. Moreover, current antifungal therapy frequently has an unfavorable outcome. Zygomycota are resistant to some of the routinely used antifungals, among them azoles (except posaconazole) and echinocandins. The typical treatment consists of surgical debridement of the infected tissues accompanied by amphotericin B administration. The latter has strong nephrotoxic side effects, which make it unsuitable for prophylaxis. Delayed administration of amphotericin and excision of mycelium-containing tissues worsens survival prognoses. More than 30 species of Zygomycota are involved in human infections, among them Mucorales is the most abundant. Prognosis and treatment suggestions differ for each species, which makes fast and reliable diagnosis essential. Serum sample PCR-based identification often gives false-negative results; culture-based identification is time-consuming and not always feasible. With the dawn of Zygomycota sequencing projects significant advancement is expected, as in the case of treatment of Ascomycota infections.

Endemic fungal infections in solid organ and hematopoietic cell transplant recipients enrolled in the Transplant-Associated Infection Surveillance Network (TRANSNET)

BACKGROUND

Invasive fungal infections are a major cause of morbidity and mortality among solid organ transplant (SOT) and hematopoietic cell transplant (HCT) recipients, but few data have been reported on the epidemiology of endemic fungal infections in these populations.

METHODS

Fifteen institutions belonging to the Transplant-Associated Infection Surveillance Network prospectively enrolled SOT and HCT recipients with histoplasmosis, blastomycosis, or coccidioidomycosis occurring between March 2001 and March 2006.

RESULTS

A total of 70 patients (64 SOT recipients and 6 HCT recipients) had infection with an endemic mycosis, including 52 with histoplasmosis, 9 with blastomycosis, and 9 with coccidioidomycosis. The 12-month cumulative incidence rate among SOT recipients for histoplasmosis was 0.102%. Occurrence of infection was bimodal; 28 (40%) infections occurred in the first 6 months post transplantation, and 24 (34%) occurred between 2 and 11 years post transplantation. Three patients were documented to have acquired infection from the donor organ. Seven SOT recipients with histoplasmosis and 3 with coccidioidomycosis died (16%); no HCT recipient died.

CONCLUSIONS

This 5-year multicenter prospective surveillance study found that endemic mycoses occur uncommonly in SOT and HCT recipients, and that the period at risk extends for years after transplantation.

Mouse model of invasive fungal infection

The mouse intravenous (IV) challenge model of Candida albicans invasive fungal infection has been widely used to study the importance of the innate immune system in these infections. This chapter describes this well-characterized model, where fungal cells are administered directly into the mouse bloodstream to initiate a systemic infection. The preparation of tissue samples from infected mice to allow evaluation of disease progression and host responses is also described.

Genetic PTX3 deficiency and aspergillosis in stem-cell transplantation

BACKGROUND

The soluble pattern-recognition receptor known as long pentraxin 3 (PTX3) has a nonredundant role in antifungal immunity. The contribution of single-nucleotide polymorphisms (SNPs) in PTX3 to the development of invasive aspergillosis is unknown.

METHODS

We screened an initial cohort of 268 patients undergoing hematopoietic stem-cell transplantation (HSCT) and their donors for PTX3 SNPs modifying the risk of invasive aspergillosis. The analysis was also performed in a multicenter study involving 107 patients with invasive aspergillosis and 223 matched controls. The functional consequences of PTX3 SNPs were investigated in vitro and in lung specimens from transplant recipients.

RESULTS

Receipt of a transplant from a donor with a homozygous haplotype (h2/h2) in PTX3 was associated with an increased risk of infection, in both the discovery study (cumulative incidence, 37% vs. 15%; adjusted hazard ratio, 3.08; P=0.003) and the confirmation study (adjusted odds ratio, 2.78; P=0.03), as well as with defective expression of PTX3. Functionally, PTX3 deficiency in h2/h2 neutrophils, presumably due to messenger RNA instability, led to impaired phagocytosis and clearance of the fungus.

CONCLUSIONS

Genetic deficiency of PTX3 affects the antifungal capacity of neutrophils and may contribute to the risk of invasive aspergillosis in patients treated with HSCT. (Funded by the European Society of Clinical Microbiology and Infectious Diseases and others.).

Systemic antifungal prophylaxis after hematopoietic stem cell transplantation: a meta-analysis

BACKGROUND

Hematopoietic stem transplant recipients are subject to increased risk for invasive fungal infections.

OBJECTIVE

This meta-analysis was undertaken to explore the comparative effectiveness of systemic antifungal prophylaxis in hematopoietic stem cell transplant recipients.

METHODS

We searched PubMed and The Cochrane Register of Randomized Controlled Trials up to March 2013 for randomized studies on systemic antifungal prophylaxis after hematopoietic stem cell transplantation. We performed a meta-analysis on the relative effectiveness of systemic antifungal prophylaxis on proven or probable invasive fungal infections using direct and indirect effects. Relative effectiveness was reported as odds ratio (OR) for invasive fungal infections, causative agent, empirical antifungal therapy, and withdrawals due to drug adverse events.

RESULTS

Twenty evaluable studies provided data on 4823 patients. The risk for invasive fungal infections while on prophylaxis was 5.1% (95% CI, 3.6-6.8%). In patients receiving fluconazole, risks of proven or probable invasive fungal infections (OR = 0.24; 95% CI, 0.11-0.50; number needed to treat [NNT] = 8), systemic candidiasis (OR = 0.11; 95% CI, 0.05-0.24; NNT = 7), and overall need for empiric antifungal treatment (OR = 0.60; 95% CI, 0.44-0.82; NNT = 8) were reduced compared with patients receiving placebo. Itraconazole was more effective than fluconazole for the prevention of aspergillosis (OR = 0.40; 95% CI, 0.19-0.83; NNT = 23) at the expense of more frequent withdrawals (OR = 3.01; 95% CI, 1.77-5.13; number needed to harm = 6). Micafungin was marginally more effective than fluconazole for the prevention of all mold infections (OR = 0.35; 95% CI, 0.10-1.18; NNT = 79) and invasive aspergillosis (OR = 0.19; 95% CI, 0.03-1.11; NNT = 78) and reducing the need for empiric antifungal treatment (OR = 0.40; 95% CI, 0.13-1.21; NNT = 8). There was a relative lack of comparisons between different antifungal prophylactic strategies, including the newer azoles, voriconazole and posaconazole, in this population. Direct effects derived from single studies showed marginally significant effects for voriconazole compared with fluconazole regarding invasive aspergillosis (OR = 0.50; 95% CI, 0.20-1.20; NNT = 35) and the need for empiric treatment (OR = 0.72; 95% CI, 0.50-1.06; NNT = 15). Voriconazole compared with itraconazole (OR = 0.59; 95% CI, 0.40-0.88; NNT = 8) and posaconazole compared with amphotericin B (OR = 0.28; 95% CI, 0.06-1.24, marginal significance; NNT = 3) were better regarding empirical antifungal treatment.

CONCLUSIONS

Even when on antifungal therapy, invasive fungal infection will develop in 1 of 20 patients undergoing hematopoietic stem cell transplantation. There is evidence for the comparable effectiveness of different antifungal drugs used for prophylaxis. Fluconazole is the most widely studied agent, but micafungin might prove to be more effective. There is a relative paucity of studies for the newer azoles, although both voriconazole and posaconazole give proof of their comparative or higher effectiveness to fluconazole in single randomized studies.

Amphotericin B formulations: a comparative review of efficacy and toxicity

Because of the increasing prevalence and changing microbiological spectrum of invasive fungal infections, some form of amphotericin B still provides the most reliable and broad spectrum therapeutic alternative. However, the use of amphotericin B deoxycholate is accompanied by dose-limited toxicities, most importantly, infusion-related reactions and nephrotoxicity. In an attempt to improve the therapeutic index of amphotericin B, three lipid-associated formulations were developed, including amphotericin B lipid complex (ABLC), liposomal amphotericin B (L-AmB), and amphotericin B colloidal dispersion (ABCD). The lipid composition of all three of these preparations differs considerably and contributes to substantially different pharmacokinetic parameters. ABLC is the largest of the lipid preparations. Because of its size, it is taken up rapidly by macrophages and becomes sequestered in tissues of the mononuclear phagocyte system such as the liver and spleen. Consequently, compared with the conventional formulation, it has lower circulating amphotericin B serum concentrations, reflected in a marked increase in volume of distribution and clearance. Lung levels are considerably higher than those achieved with other lipid-associated preparations. The recommended therapeutic dose of ABLC is 5 mg/kg/day. Because of its small size and negative charge, L-AmB avoids substantial recognition and uptake by the mononuclear phagocyte system. Therefore, a single dose of L-AmB results in a much higher peak plasma level (Cmax) than conventional amphotericin B deoxycholate and a much larger area under the concentration-time curve. Tissue concentrations in patients receiving L-AmB tend to be highest in the liver and spleen and much lower in kidneys and lung. Recommended therapeutic dosages are 3-6 mg/kg/day. After intravenous infusion, ABCD complexes remain largely intact and are rapidly removed from the circulation by cells of the macrophage phagocyte system. On a milligram-to-milligram basis, the Cmax achieved is lower than that attained by conventional amphotericin B, although the larger doses of ABCD that are administered produce an absolute level that is similar to amphotericin B. ABCD exhibits dose-limiting, infusion-related toxicities; consequently, the administered dosages should not exceed 3-4 mg/kg/day. The few comparative clinical trials that have been completed with the lipid-associated formulations have not demonstrated important clinical differences among these agents and amphotericin B for efficacy, although there are significant safety benefits of the lipid products. Furthermore, only one published trial has ever compared one lipid product against another for any indication. The results of these trials are particularly difficult to interpret because of major heterogeneities in study design, disease definitions, drug dosages, differences in clinical and microbiological endpoints as well as specific outcomes examined. Nevertheless, it is possible to derive some general conclusions given the available data. The most commonly studied syndrome has been empiric therapy for febrile neutropenic patients, where the lipid-associated preparations did not appear to provide a survival benefit over conventional amphotericin B deoxycholate, but did offer a significant advantage for the prevention of various breakthrough invasive fungal infections. For treatment of documented invasive fungal infections that usually involved hematological malignancy patients, no individual randomized trial has demonstrated a mortality benefit due to therapy with one of the lipid formulations. Results from meta-analyses have been contradictory, with one demonstrating a mortality benefit from all-cause mortality and one that did not demonstrate a mortality benefit. In the only published study to examine HIV-infected patients with disseminated histoplasmosis, clinical success and mortality were significantly better with L-AmB compared with amphotericin B deoxycholate; there were no differences in microbiological outcomes between treatment groups. The lipid-associated preparations were not significantly better than amphotericin B deoxycholate for treatment of AIDS-associated acute cryptococcal meningitis for either clinical or microbiological outcomes that were studied. In all of the trials that specifically examined renal toxicity, the lipid-associated formulations were significantly less nephrotoxic than amphotericin B deoxycholate. Infusion-related reactions occurred less frequently with L-AmB when compared with amphotericin B deoxycholate; however, ABCD had equivalent or more frequent infusion-related reactions than conventional amphotericin B, and this resulted in the cessation of at least one clinical trial. At the present time, this particular lipid formulation is no longer commercially available. For the treatment of most invasive fungal infections, an amphotericin B lipid formulation provides a safer alternative than conventional amphotericin B, with at least equivalent efficacy. As the cost of therapy with these agents continues to decline, these drugs will likely maintain their important role in the antifungal drug armamentarium because of their efficacy and improved safety profile.

Synthesis and antifungal activity of ASP9726, a novel echinocandin with potent Aspergillus hyphal growth inhibition

The synthesis and antifungal activity of ASP9726, a novel echinocandin with potent Aspergillus hyphal growth inhibition and significantly improved MIC against Candida parapsilosis and echinocandin resistant-Candida is described.

Molecular methods for detection of invasive fungal infections and mycobacteria and their clinical significance in hematopoietic stem cell transplantation

Infection remains an important source of morbidity and mortality in patients who undergo hematopoietic stem cell transplantation (HSCT). In the immune reconstitution period after transplantation, HSCT recipients are most likely to have bacterial or fungal infections. Invasive fungal infections (IFIs) and mycobacterial infections (MBIs) are among the complications of HSCT, with high morbidity and mortality rates. Early diagnosis of both is crucial in order to manipulate the disease and to avoid fulminant outcomes. This chapter reviews the current knowledge on the molecular diagnosis of IFIs and MBIs in HSCT recipients, describing two different polymerase chain reaction (PCR)-based methods, one commercial (qPCR, Roche) and one in-house IS6110-based protocol.

Eosinophil deficiency compromises lung defense against Aspergillus fumigatus

Exposure to the mold Aspergillus fumigatus may result in allergic bronchopulmonary aspergillosis, chronic necrotizing pulmonary aspergillosis, or invasive aspergillosis (IA), depending on the host's immune status. Neutrophil deficiency is the predominant risk factor for the development of IA, the most life-threatening condition associated with A. fumigatus exposure. Here we demonstrate that in addition to neutrophils, eosinophils are an important contributor to the clearance of A. fumigatus from the lung. Acute A. fumigatus challenge in normal mice induced the recruitment of CD11b+ Siglec F+ Ly-6G(lo) Ly-6C(neg) CCR3+ eosinophils to the lungs, which was accompanied by an increase in lung Epx (eosinophil peroxidase) mRNA levels. Mice deficient in the transcription factor dblGATA1, which exhibit a selective deficiency in eosinophils, demonstrated impaired A. fumigatus clearance and evidence of germinating organisms in the lung. Higher burden correlated with lower mRNA expression of Epx (eosinophil peroxidase) and Prg2 (major basic protein) as well as lower interleukin 1β (IL-1β), IL-6, IL-17A, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and CXCL1 levels. However, examination of lung inflammatory cell populations failed to demonstrate defects in monocyte/macrophage, dendritic cell, or neutrophil recruitment in dblGATA1-deficient mice, suggesting that the absence of eosinophils in dlbGATA1-deficient mice was the sole cause of impaired lung clearance. We show that eosinophils generated from bone marrow have potent killing activity against A. fumigtaus in vitro, which does not require cell contact and can be recapitulated by eosinophil whole-cell lysates. Collectively, our data support a role for eosinophils in the lung response after A. fumigatus exposure.

An update on pulmonary complications of hematopoietic stem cell transplantation

The indications for hematopoietic stem cell transplantation (HSCT) continue to expand. However, the risk for pulmonary complications post-HSCT continues to be high. Early recognition and treatment of pulmonary complications may improve outcomes. This is an overview of diagnosis, manifestations, and treatment of the most common infectious and noninfectious pulmonary complications post-HSCT. Knowing the patient's timeframe post-HSCT (preengraftment, postengraftment, late), type of HSCT (allogeneic vs autologous), radiographic findings, and clinical presentation can help to differentiate between the many pulmonary complications. This article will also address pretransplantation evaluation and infectious and noninfectious complications in the patient post-HSCT. While mortality post-HSCT continues to improve, respiratory failure continues to be the leading cause of ICU admissions for patients who have undergone HSCT. Mechanical ventilation is a predictor of poor outcomes in these patients, and further research is needed regarding their critical care management, treatment options for noninfectious pulmonary complications, and mortality prediction models posttransplantation.

Proteomic demonstration of the recurrent presence of inter-alpha-inhibitor H4 heavy-chain during aspergillosis induced in an animal model

Invasive pulmonary aspergillosis remains a matter of great concern in oncology/haematology, intensive care units and organ transplantation departments. Despite the availability of various diagnostic tools with attractive features, new markers of infection are required for better medical care. We therefore looked for potential pulmonary biomarkers of aspergillosis, by carrying out two-dimensional (2D) gel electrophoresis comparing the proteomes of bronchial-alveolar lavage fluids (BALF) from infected rats and from control rats presenting non-specific inflammation, both immunocompromised. A bioinformatic analysis of the 2D-maps revealed significant differences in the abundance of 20 protein spots (ANOVA P-value<0.01; q-value<0.03; power>0.8). One of these proteins, identified by mass spectrometry, was considered of potential interest: inter-alpha-inhibitor H4 heavy-chain (ITIH4), characterised for the first time in this infectious context. Western blotting confirmed its overabundance in all infected BALF, particularly at early stages of murine aspergillosis. Further investigations were carried on rat serum, and confirmed that ITIH4 levels increased during experimental aspergillosis. Preliminary results in human samples strengthened this trend. To our knowledge, this is the first description of the involvement of ITIH4 in aspergillosis.

Enhancing molecular approaches for diagnosis of fungal infections

Molecular tests can improve the diagnosis of fungal infections. Despite the increasing application for fungal detection, molecular tests are still not accepted as a diagnostic criterion to define invasive fungal diseases. This limitation is largely due to a lack of a standardized method. Method standardization can be achieved by following a consensus protocol developed by a working group, by performing a molecular test in a centralized laboratory or by using a commercial assay that provides a standardized method and quality-controlled reagents. Forming a consortium or a working group consisting of large-scale diagnostic mycology laboratories can accelerate the process of validating and implementing a commercial molecular assay for clinical use through a joint effort between industry partners and clinicians. Development of molecular tests not only for the detection of fungi but also for the identification of antifungal drug resistance directly in blood, bronchoalveolar lavage fluid, cerebrospinal fluid, and formalin-fixed and paraffin-embedded tissues greatly enhances fungal diagnostic capacities. Advances of developing quantitative assays and RNA detection platforms may provide another avenue to further improve fungal diagnostics.

Endemic mycoses in immunocompromised hosts

Endemic mycoses remain a significant cause of morbidity and mortality among immunocompromised patients. As the number of immunosuppressed individuals increases worldwide, the incidence of endemic mycoses is also expected to rise. In immunocompromised patients, endemic mycoses can present in atypical fashion, cause more severe and/or disseminated disease, and result in higher mortality. Despite several noteworthy advances over the past decade, significant challenges remain with regard to the prevention, diagnosis, and therapy of endemic mycoses in immunocompromised hosts. This review highlights important developments related to the epidemiology, diagnosis, treatment, and prevention of commonly encountered endemic mycoses. We also discuss emerging topics, knowledge gaps, and areas of future research.

Clinical-scale generation of multi-specific anti-fungal T cells targeting Candida, Aspergillus and mucormycetes

BACKGROUND AIMS

Invasive fungal infections, in particular, infections caused by Candida, Aspergillus and mucormycetes, are a major cause of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation. Adoptive transfer of donor-derived anti-fungal T cells shows promise to restore immunity and to offer a cure. Because T cells recognize only specific epitopes, the low rate of patients in which the causal fungal pathogen can be identified and the considerable number of patients with co-infection with several genera or species of fungi significantly limit the application of adoptive immunotherapy.

METHODS

Using the interferon-γ secretion assay, we isolated multi-specific human anti-fungal T cells after simultaneous stimulation with cellular extracts of Aspergillus fumigatus, Candida albicans and Rhizopus oryzae. Cells were phenotypically and functionally characterized by flow cytometry.

RESULTS

Of a total of 1.1 × 10(9) peripheral blood mononuclear cells, a median number of 5.2 × 10(7) CD3+ CD4+ T cells was generated within 12 days. This cell population consisted of activated memory TH1 cells and reproducibly responded to a multitude of Aspergillus spp., Candida spp. and mucormycetes with interferon-γ production. On re-stimulation, the generated T cells proliferated and enhanced anti-fungal activity of phagocytes and showed reduced alloreactivity compared with the original cell fraction.

CONCLUSIONS

Our rapid and simple method of simultaneously generating functionally active multi-specific T cells that recognize a wide variety of medically relevant fungi may form the basis for future clinical trials investigating adoptive immunotherapy in allogeneic hematopoietic stem cell transplantation recipients with invasive fungal infection.

Impact of in vivo triazole and echinocandin combination therapy for invasive pulmonary aspergillosis: enhanced efficacy against Cyp51 mutant isolates

Previous studies examining combination therapy for invasive pulmonary aspergillosis (IPA) have revealed conflicting results, including antagonism, indifference, and enhanced effects. The most commonly employed combination for this infection includes a mold-active triazole and echinocandin. Few studies have evaluated combination therapy from a pharmacodynamic (PD) perspective, and even fewer have examined combination therapy against both wild-type and azole-resistant Cyp51 mutant isolates. The current studies aim to fill this gap in knowledge. Four Aspergillus fumigatus isolates were utilized, including a wild-type strain, an Fks1 mutant (posaconazole susceptible and caspofungin resistant), and two Cyp51 mutants (posaconazole resistant). A neutropenic murine model of IPA was used for the treatment studies. The dosing design included monotherapy with posaconazole, monotherapy with caspofungin, and combination therapy with both. Efficacy was determined using quantitative PCR, and results were normalized to known quantities of conidia (conidial equivalents [CE]). The static dose, 1-log kill dose, and associated PD target area under the curve (AUC)/MIC ratio were determined for monotherapy and combination therapy. Monotherapy experiments revealed potent activity for posaconazole, with reductions of 3 to 4 log10 Aspergillus CE/ml with the two "low"-MIC isolates. Posaconazole alone was less effective for the two isolates with higher MICs. Caspofungin monotherapy did not produce a significant decrease in fungal burden for any strain. Combination therapy with the two antifungals did not enhance efficacy for the two posaconazole-susceptible isolates. However, the drug combination produced synergistic activity against both posaconazole-resistant isolates. Specifically, the combination resulted in a 1- to 2-log10 decline in burden that would not have been predicted based on the monotherapy results for each drug. This corresponded to a reduction in the free-drug posaconazole AUC/MIC ratio needed for stasis of up to 17-fold. The data suggest that combination therapy using a triazole and an echinocandin may be a beneficial treatment strategy for triazole-resistant isolates.

Diagnosis and treatment of invasive fungal infections focus on liposomal amphotericin B

Invasive fungal infections (IFIs) are responsible for significant morbidity and mortality, especially in immunocompromised patients and in those requiring admission to an intensive care unit. The epidemiology of IFI is changing, and an increment in non-Aspergillus filamentous fungi and non-Candida albicans species has been observed. The present paper reviews the epidemiology and diagnosis of IFIs. Regarding the treatment of IFIs, it focuses primarily on the role of liposomal amphotericin B in this setting. The main recommendations put forth by expert societies and groups are discussed.

Targeted gene deletion in Aspergillus fumigatus using microbial machinery and a recyclable marker

The emerging invasive fungal pathogen Aspergillus fumigatus causes very serious infections among immunocompromised patient populations. While the genome of this pathogen has been sequenced, a major barrier to better understanding the complex biology of this eukaryotic organism is a lack of tools for efficient genetic manipulation. To improve upon this, we have generated a new gene deletion system for A. fumigatus using yeast recombinational cloning and Agrobacterium tumefaciens mediated transformation (ATMT) employing a recyclable marker system. This system reduced the time for generating a gene deletion strain in our hands by two-thirds (12 weeks to 3 weeks) using minimal human labor, and we demonstrate that it can be used to efficiently generate multiple gene deletions within a single strain.

Voriconazole serum concentrations in obese and overweight immunocompromised patients: a retrospective review

STUDY OBJECTIVE

To evaluate the relationship between voriconazole dose and corresponding serum concentrations in obese and overweight immunocompromised patients.

DESIGN

Retrospective medical record review.

SETTING

National Cancer Institute-designated comprehensive cancer center.

PATIENTS

A total of 92 patients with hematologic malignancies and/or hematopoietic stem cell transplants who received voriconazole and had reported steady-state serum concentrations (peak, random, or trough) during 2005-2010; 124 serum concentrations were available for analysis.

MEASUREMENTS AND MAIN RESULTS

Data on patient demographics, voriconazole concentrations, and other clinical and safety data were collected. Patients were stratified based on body mass index (BMI). Patients with higher BMIs tended to have significantly higher median random voriconazole concentrations with intravenous administration (6.4 mg/L for BMI ≥ 25 kg/m(2) vs 2.8 mg/L for BMI < 25 kg/m(2), p=0.04). This trend was more notable with the intravenous than the oral formulations. With the oral formulation, patients with a BMI of 25 kg/m(2) or greater had a median random concentration of 2.8 mg/L compared with 2.0 mg/L in patients with a BMI less than 25 kg/m(2) (p=0.18). Patients with a BMI of 25 kg/m(2) or greater also had a higher median daily voriconazole dose (640 vs 400 mg, p<0.001). No significant differences were noted in factors that would affect oral absorption of voriconazole (e.g., graft-versus-host disease) among BMI groups. When comparing all voriconazole concentrations, higher concentrations were associated with a greater percentage of patients who had alanine aminotransferase levels of more than 3 times the upper limit of normal. Patients with voriconazole random concentrations of 2 mg/L or greater had higher response rates (50%) than patients with concentrations lower than 2 mg/L (33%).

CONCLUSION

Standard voriconazole dosing using actual body weight in obese and overweight patients resulted in higher associated serum concentrations. Dosing using adjusted body weight may be necessary in this population in order to achieve optimal concentrations while preventing the potential for increased toxicity.

Isavuconazole (BAL4815) pharmacodynamic target determination in an in vivo murine model of invasive pulmonary aspergillosis against wild-type and cyp51 mutant isolates of Aspergillus fumigatus

Invasive pulmonary aspergillosis (IPA) continues to rise in concert with increasing numbers of immune suppression techniques to treat other medical conditions and transplantation. Despite these advances, morbidity and mortality rates remain unacceptably high. One strategy used to optimize outcomes is antifungal pharmacodynamic (PD) examination. We explored the pharmacodynamics of a new triazole in development, isavuconazole, in a murine neutropenic IPA model. Ten A. fumigatus isolates were used, including four wild-type isolates and six cyp51 mutants. The MIC range was 0.125 to 8 mg/liter. Following infection, groups of mice were treated orally with the prodrug (BAL8557) at 40 to 640 mg/kg/12 h for 7 days. Efficacy was determined by quantitative PCR of lung homogenates. At the start of therapy, mice had 4.97 log10 conidial equivalents (CE)/ml of lung homogenate, and this increased to 6.82 log10 CE/ml of lung homogenate in untreated animals. The infection model was uniformly lethal in untreated control mice. The PD target endpoints examined included the static-dose AUC/MIC ratio and the 1-log10 killing AUC/MIC ratio. A stasis endpoint was achieved for all isolates with an MIC of ≤1 mg/liter and 1-log10 killing in all isolates with an MIC of ≤0.5 mg/liter, regardless of the presence or absence of the cyp51 mutation. The static-dose range was 65 to 617 mg/kg/12 h. The corresponding median free-drug AUC/MIC ratio was near 5. The 1-log10 killing dose range was 147 to 455 mg/kg/12 h, and the corresponding median free-drug AUC/MIC ratio was 11.1. These values are similar to those previously reported for other triazoles.

Transcriptional activation of heat shock protein 90 mediated via a proximal promoter region as trigger of caspofungin resistance in Aspergillus fumigatus

Invasive aspergillosis is a deadly infection for which new antifungal therapies are needed. Heat shock protein 90 (Hsp90) is an essential chaperone in Aspergillus fumigatus representing an attractive antifungal target. Using a thiamine-repressible promoter (pthiA), we showed that genetic repression of Hsp90 significantly reduced virulence in a murine model of invasive aspergillosis. Moreover, substituting the A. fumigatus hsp90 promoter with 2 artificial promoters (potef, pthiA) and the Candida albicans hsp90 promoter resulted in hypersensitivity to caspofungin and abolition of the paradoxical effect (resistance at high caspofungin concentrations). By inducing truncations in the hsp90 promoter, we identified a 100-base pair proximal sequence that triggers a significant increase of hsp90 expression (≥1.5-fold) and is essential for the paradoxical effect. Preventing this increase of hsp90 expression was sufficient to abolish the paradoxical effect and therefore optimize the antifungal activity of caspofungin.

Crossover fungal pathogens: the biology and pathogenesis of fungi capable of crossing kingdoms to infect plants and humans

The outbreak of fungal meningitis associated with contaminated methylprednisolone acetate has thrust the importance of fungal infections into the public consciousness. The predominant pathogen isolated from clinical specimens, Exserohilum rostratum (teleomorph: Setosphaeria rostrata), is a dematiaceous fungus that infects grasses and rarely humans. This outbreak highlights the potential for fungal pathogens to infect both plants and humans. Most crossover or trans-kingdom pathogens are soil saprophytes and include fungi in Ascomycota and Mucormycotina phyla. To establish infection, crossover fungi must overcome disparate, host-specific barriers, including protective surfaces (e.g. cuticle, skin), elevated temperature, and immune defenses. This review illuminates the underlying mechanisms used by crossover fungi to cause infection in plants and mammals, and highlights critical events that lead to human infection by these pathogens. Several genes including veA, laeA, and hapX are important in regulating biological processes in fungi important for both invasive plant and animal infections.

Epidemiology and treatment of mucormycosis

Mucormycosis is an uncommon but aggressive opportunistic fungal infection that afflicts patients with severe underlying immunosuppression, uncontrolled hyperglycemia and/or ketoacidosis, patients with iron overload resulting from frequent blood transfusions or blood disorders and occasionally healthy patients who are inoculated with fungal spores through traumatic injuries. The clinical presentation of mucormycosis is initially indistinguishable from other common infections, and if not diagnosed early and aggressively treated, it is almost always fatal. In this article we summarize recent changes in the epidemiology of mucormycosis, discuss diagnostic and clinical clues suggestive of the infection and provide a general strategy for managing the infection in the absence of data from well-controlled, prospective clinical trials.

Phosphorylation of Calcineurin at a novel serine-proline rich region orchestrates hyphal growth and virulence in Aspergillus fumigatus

The fungus Aspergillus fumigatus is a leading infectious killer in immunocompromised patients. Calcineurin, a calmodulin (CaM)-dependent protein phosphatase comprised of calcineurin A (CnaA) and calcineurin B (CnaB) subunits, localizes at the hyphal tips and septa to direct A. fumigatus invasion and virulence. Here we identified a novel serine-proline rich region (SPRR) located between two conserved CnaA domains, the CnaB-binding helix and the CaM-binding domain, that is evolutionarily conserved and unique to filamentous fungi and also completely absent in human calcineurin. Phosphopeptide enrichment and tandem mass spectrometry revealed the phosphorylation of A. fumigatus CnaA in vivo at four clustered serine residues (S406, S408, S410 and S413) in the SPRR. Mutation of the SPRR serine residues to block phosphorylation led to significant hyphal growth and virulence defects, indicating the requirement of calcineurin phosphorylation at the SPRR for its activity and function. Complementation analyses of the A. fumigatus ΔcnaA strain with cnaA homologs from the pathogenic basidiomycete Cryptococcus neoformans, the pathogenic zygomycete Mucor circinelloides, the closely related filamentous fungi Neurospora crassa, and the plant pathogen Magnaporthe grisea, revealed filamentous fungal-specific phosphorylation of CnaA in the SPRR and SPRR homology-dependent restoration of hyphal growth. Surprisingly, circular dichroism studies revealed that, despite proximity to the CaM-binding domain of CnaA, phosphorylation of the SPRR does not alter protein folding following CaM binding. Furthermore, mutational analyses in the catalytic domain, CnaB-binding helix, and the CaM-binding domains revealed that while the conserved PxIxIT substrate binding motif in CnaA is indispensable for septal localization, CaM is required for its function at the hyphal septum but not for septal localization. We defined an evolutionarily conserved novel mode of calcineurin regulation by phosphorylation in filamentous fungi in a region absent in humans. These findings suggest the possibility of harnessing this unique SPRR for innovative antifungal drug design to combat invasive aspergillosis.

Posaconazole concentrations after allogeneic hematopoietic stem cell transplantation

INTRODUCTION

Posaconazole is recommended for prophylaxis of fungal infections and for salvage therapy of invasive aspergillosis after stem cell transplantation. An impact of drug concentration on efficacy has been suggested.

METHODS

In this study, we investigated serum levels of posaconazole in 262 samples from 64 allogeneic stem cell recipients.

RESULTS

A high degree of interindividual variation was observed. Concentrations were significantly higher for male patients compared with female patients (median 570 and 426 ng/mL, respectively), but no differences for age or dosing groups (400 mg twice daily [BID] or 200 mg three times a day) could be detected. The predictive value of the first determined posaconazole concentration in steady state and of a concentration >500 and 700 ng/mL at any time was evaluated, compared with patients with a first level <300 ng/mL (mean 10.3%, median 0%).

CONCLUSION

In patients receiving 400 mg BID, the mean rate of serum levels >500 ng/mL in subsequent determinations was higher, if the first serum concentration during steady state was >300 ng/mL (mean 61.1%, median 60%, P = 0.002) or >500 ng/mL (67.7%, median 75%, P = 0.002). Based on this retrospective analysis, a posaconazole serum concentration >500 ng/mL at any time point might also help to predict sufficient drug concentrations.

A prospective, cohort, multicentre study of candidaemia in hospitalized adult patients with haematological malignancies

Invasive candidiasis is a life-threatening infection in patients with haematological malignancies. The objective of our study was to determine the incidence, microbiological characteristics and clinical outcome of candidaemia among hospitalized adult patients with haematological malignancies. This is a population-based, prospective, multicentre study of patients ≥ 18 years admitted to haematology and/or haematopoietic stem cell transplantation units of nine tertiary care Greek hospitals from January 2009 through to February 2012. Within this cohort, we conducted a nested case-control study to determine the risk factors for candidaemia. Stepwise logistic regression was used to identify independent predictors of 28-day mortality. Candidaemia was detected in 40 of 27,864 patients with haematological malignancies vs. 967 of 1,158,018 non-haematology patients for an incidence of 1.4 cases/1000 admissions vs. 0.83/1000 respectively (p <0.001). Candidaemia was caused predominantly (35/40, 87.5%) by non-Candida albicans species, particularly Candida parapsilosis (20/40, 50%). In vitro resistance to at least one antifungal agent was observed in 27% of Candida isolates. Twenty-one patients (53%) developed breakthrough candidaemia while receiving antifungal agents. Central venous catheters, hypogammaglobulinaemia and a high APACHE II score were independent risk factors for the development of candidaemia. Crude mortality at day 28 was greater in those with candidaemia than in control cases (18/40 (45%) vs. 9/80 (11%); p <0.0001). In conclusion, despite antifungal prophylaxis, candidaemia is a relatively frequent infection associated with high mortality caused by non-C. albicans spp., especially C. parapsilosis. Central venous catheters and hypogammaglobulinaemia are independent risk factors for candidaemia that provide potential targets for improving the outcome.

Aspergillus-associated airway disease, inflammation, and the innate immune response

Aspergillus moulds exist ubiquitously as spores that are inhaled in large numbers daily. Whilst most are removed by anatomical barriers, disease may occur in certain circumstances. Depending on the underlying state of the human immune system, clinical consequences can ensue ranging from an excessive immune response during allergic bronchopulmonary aspergillosis to the formation of an aspergilloma in the immunocompetent state. The severest infections occur in those who are immunocompromised where invasive pulmonary aspergillosis results in high mortality rates. The diagnosis of Aspergillus-associated pulmonary disease is based on clinical, radiological, and immunological testing. An understanding of the innate and inflammatory consequences of exposure to Aspergillus species is critical in accounting for disease manifestations and preventing sequelae. The major components of the innate immune system involved in recognition and removal of the fungus include phagocytosis, antimicrobial peptide production, and recognition by pattern recognition receptors. The cytokine response is also critical facilitating cell-to-cell communication and promoting the initiation, maintenance, and resolution of the host response. In the following review, we discuss the above areas with a focus on the innate and inflammatory response to airway Aspergillus exposure and how these responses may be modulated for therapeutic benefit.

Utility of bronchoalveolar lavage fluid galactomannan alone or in combination with PCR for the diagnosis of invasive aspergillosis in adult hematology patients: a systematic review and meta-analysis

BACKGROUND

The clinical utility of bronchoalveolar lavage (BAL) fluid galactomannan (GM) for the early diagnosis of invasive aspergillosis (IA) varies widely across studies mainly due to heterogeneity of the studied populations.

METHODS

We conducted a systematic review and meta-analysis of 16 studies involving 783 adults with hematological malignancies to derive summary estimates of the overall accuracy of BAL-GM for diagnosing IA.

FINDINGS

Summary estimates of BAL-GM using an optical density (OD) index cutoff value of 1.5 for proven and probable IA were: sensitivity 0.92 (95% CI = 0.48-0.99), specificity 0.98 (95% CI = 0.78-1.00), positive likelihood ratio 53.7 (95% CI = 3.7-771.8), and negative likelihood ratio 0.08 (95% CI = 0.01-0.83). Comparing serum GM and Aspergillus PCR testing on BAL fluid, BAL-GM conferred greater sensitivity, but lower specificity than the serum GM test, and similar specificity as the PCR assay. The use of BAL-GM with serum GM or BAL-PCR tests increased the sensitivity moderately when a positive result was defined by either assay.

INTERPRETATION

GM quantification in BAL fluid at an OD index cutoff value of 1.5 has excellent sensitivity and specificity to assist clinical decision-making in confirming or excluding a diagnosis of IA when results are interpreted with clinical findings. Additional research investigating the effects of antifungal agents, optimal timing and processing of BAL sampling are needed to improve the diagnostic accuracy of BAL-GM testing.