Detection of circulating galactomannan for the diagnosis and management of invasive aspergillosis

Utility of galactomannan antigen detection in bronchoalveolar lavage fluid in immunocompromised patients

Diagnosis of invasive pulmonary aspergillosis (IPA) is a challenging process in immunocompromised patients. Galactomannan (GM) antigen detection in bronchoalveolar lavage (BAL) fluid is a method to detect IPA with improved sensitivity over conventional studies. We sought to determine the diagnostic yield of BAL GM assay in a diverse population of immunocompromised patients. A retrospective review of 150 fiberoptic bronchoscopy (FOB) with BAL for newly diagnosed pulmonary infiltrate in immunocompromised patients was performed. Patient information, procedural details and laboratory studies were collected. BAL and serum samples were evaluated for GM using enzyme-linked immunoassay. Of 150 separate FOB with BAL, BAL GM was obtained in 143 samples. There were 31 positive BAL GM assays. In those 31 positive tests, 13 were confirmed as IPA, giving a positive predictive value of 41.9%. There was one false negative BAL GM. Of the 18 false positive BAL GM, 4 were receiving piperacillin-tazobactam and 11 were receiving an alternative beta-lactam antibiotic. BAL GM assay shows excellent sensitivity for diagnosing IPA. There was a significant number of false positive BAL GM assays and several of those patients were receiving beta-lactam antibiotics at the time of bronchoscopy.

Diagnostic performance of an Aspergillus-specific nested PCR assay in cerebrospinal fluid samples of immunocompromised patients for detection of central nervous system aspergillosis

Central nervous system (CNS) invasive aspergillosis (IA) is a fatal complication in immunocompromised patients. Confirming the diagnosis is rarely accomplished as invasive procedures are impaired by neutropenia and low platelet count. Cerebrospinal fluid (CSF) cultures or galactomannan (GM) regularly yield negative results thus suggesting the need for improving diagnostic procedures. Therefore the performance of an established Aspergillus-specific nested polymerase chain reaction assay (PCR) in CSF samples of immunocompromised patients with suspicion of CNS IA was evaluated. We identified 113 CSF samples from 55 immunocompromised patients for whom CNS aspergillosis was suspected. Of these patients 8/55 were identified as having proven/probable CNS IA while the remaining 47 patients were classified as having either possible (n = 22) or no CNS IA (n = 25). PCR positivity in CSF was observed for 8/8 proven/probable, in 4/22 possible CNS IA patients and in 2/25 NoIA patients yielding sensitivity and specificity values of 1.0 (95% CI 0.68–1) and 0.93 (95% CI 0.77–0.98) and a positive likelihood ratio of 14 and negative likelihood ratio of 0.0, respectively, thus resulting in a diagnostic odds ratio of ∞. The retrospective analysis of CSF samples from patients with suspected CNS IA yielded a high sensitivity of the nested PCR assay. PCR testing of CSF samples is recommended for patients for whom CNS IA is suspected, especially for those whose clinical condition does not allow invasive procedures as a positive PCR result makes the presence of CNS IA in that patient population highly likely.

Aspergillus galactomannan antigen assay and invasive aspergillosis in pediatric cancer patients and hematopoietic stem cell transplant recipients

BACKGROUND

Invasive aspergillosis (IA) is a major cause of morbidity and mortality in immunocompromised children. We investigated the usefulness of an Aspergillus galactomannan (GM) antigen assay as a diagnostic tool for IA in pediatric cancer patients and hematopoietic cell transplantation (HCT) recipients.

PROCEDURE

The GM antigen assay results were analyzed in 749 blood samples from 99 patients. A GM index (GMI) greater than or equal to 0.5 on at least two separate occasions was considered positive. A review of the clinical data was performed for subjects with proven or probable IA.

RESULTS

Twenty-one of 23 patients with proven or probable IA had positive GM antigen test results (91.3% sensitivity, 95% CI 71.9-98.9; 81.7% specificity, 95% CI 69.6-90.5; P < 0.0001). The false-positive rate was 18.3%. Being younger than 3 years of age, having a solid tumor, and receiving HCT within 4 weeks of the test were statistically significant factors for causing false-positive results (P < 0.05). Among the 23 patients with IA (six proven, 17 probable), 16 (69.6%) had hematological malignancies, five (22.7%) had solid tumors, and two (8.7%) had primary immunodeficiency. Nineteen patients (82.6%) received HCT. The most common clinical site of IA was the lungs (91.3%), and consolidation was the most frequent finding in chest CT scans (36.8%). The mortality at 12 weeks was 43.5%.

CONCLUSIONS

Having a positive GM assay at least twice is useful in diagnosing IA in pediatric patients with cancer and HCT recipients.

Neuro-ophthalmology of invasive fungal sinusitis: 14 consecutive patients and a review of the literature

BACKGROUND

Invasive fungal sinusitis is a rare condition that usually occurs in immunocompromised patients and often presents as an orbital apex syndrome. It is frequently misdiagnosed on presentation and is almost always lethal without early treatment.

DESIGN

Retrospective case series of 14 consecutive patients with biopsy-proven invasive fungal sinusitis from four tertiary hospitals.

PARTICIPANTS

Fourteen patients (10 men and 4 women; age range 46-82 years).

METHODS

Retrospective chart review of all patients presenting with invasive fungal sinusitis between 1994 and 2010 at each hospital, with a close analysis of the tempo of the disease to identify any potential window of opportunity for treatment.

MAIN OUTCOME MEASURES

Demographic data, background medical history (including predisposing factors), symptoms, signs, radiological findings, histopathological findings, treatment approach and subsequent clinical course were recorded and analysed.

RESULTS

Only one patient was correctly diagnosed at presentation. Only two patients were not diabetic or immunocompromised. The tempo was acute in two patients, subacute in nine patients and chronic in three patients. In the subacute and chronic cases, there was about 1 week of opportunity for treatment, from the time there was a complete orbital apex syndrome, and still a chance for saving the patient, to the time there was central nervous system invasion, which was invariably fatal. Only two patients survived - both had orbital exenteration, as well as antifungal drug treatment.

CONCLUSIONS

Invasive fungal sinusitis can, rarely, occur in healthy individuals and should be suspected as a possible cause of a progressive orbital apex syndrome.

Laboratory diagnosis of invasive aspergillosis: from diagnosis to prediction of outcome

Invasive aspergillosis (IA), an infection caused by fungi in the genus Aspergillus, is seen in patients with immunological deficits, particularly acute leukaemia and stem cell transplantation, and has been associated with high rates of mortality in previous years. Diagnosing IA has long been problematic owing to the inability to culture the main causal agent A. fumigatus from blood. Microscopic examination and culture of respiratory tract specimens have lacked sensitivity, and biopsy tissue for histopathological examination is rarely obtainable. Thus, for many years there has been a great interest in nonculture-based techniques such as the detection of galactomannan, β -D-glucan, and DNA by PCR-based methods. Recent meta-analyses suggest that these approaches have broadly similar performance parameters in terms of sensitivity and specificity to diagnose IA. Improvements have been made in our understanding of the limitations of antigen assays and the standardisation of PCR-based DNA detection. Thus, in more recent years, the debate has focussed on how these assays can be incorporated into diagnostic strategies to maximise improvements in outcome whilst limiting unnecessary use of antifungal therapy. Furthermore, there is a current interest in applying these tests to monitor the effectiveness of therapy after diagnosis and predict clinical outcomes. The search for improved markers for the early and sensitive diagnosis of IA continues to be a challenge.

Fungal diagnostics: review of commercially available methods

Fungi and yeasts are critical causes of acute infection. As such, the detection and identification of these organisms are crucial in the diagnosis of affected patient populations. There is a vast array of commercial tests currently available for diagnostic purposes. These vary from traditional culture and biochemical methods to advanced multiparameter molecular tests. Recent technological advances have driven the development of rapid tests which are complementing and in some cases replacing the more traditional methods of detection. Irrespective of the method used the ultimate goal is timely detection of the infectious agent allowing appropriate treatment and improved outcome for the patient.

FungiQuant: a broad-coverage fungal quantitative real-time PCR assay

BACKGROUND

Fungal load quantification is a critical component of fungal community analyses. Limitation of current approaches for quantifying the fungal component in the human microbiome suggests the need for new broad-coverage techniques.

METHODS

We analyzed 2,085 18S rRNA gene sequences from the SILVA database for assay design. We generated and quantified plasmid standards using a qPCR-based approach. We evaluated assay coverage against 4,968 sequences and performed assay validation following the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines.

RESULTS

We designed FungiQuant, a TaqMan® qPCR assay targeting a 351 bp region in the fungal 18S rRNA gene. Our in silico analysis showed that FungiQuant is a perfect sequence match to 90.0% of the 2,617 fungal species analyzed. We showed that FungiQuant's is 100% sensitive and its amplification efficiencies ranged from 76.3% to 114.5%, with r(2)-values of >0.99 against the 69 fungal species tested. Additionally, FungiQuant inter- and intra-run coefficients of variance ranged from <10% and <20%, respectively. We further showed that FungiQuant has a limit of quantification 25 copies and a limit of detection at 5 copies. Lastly, by comparing results from human-only background DNA with low-level fungal DNA, we showed that amplification in two or three of a FungiQuant performed in triplicate is statistically significant for true positive fungal detection.

CONCLUSIONS

FungiQuant has comprehensive coverage against diverse fungi and is a robust quantification and detection tool for delineating between true fungal detection and non-target human DNA.

Evaluation of serum galactomannan detection for diagnosis of feline upper respiratory tract aspergillosis

Measurement of serum galactomannan (GM), a polysaccharide fungal cell-wall component, is a non-invasive test for early diagnosis of invasive aspergillosis in humans. Feline upper respiratory tract (URT) aspergillosis is an emerging infectious disease in cats. Diagnosis requires biopsy for procurement of tissue specimens for cytological or histological detection of fungal hyphae and for fungal culture. The aim of this study was to evaluate serum GM measurement as a non-invasive diagnostic test for URT aspergillosis in cats. A one-stage, immunoenzymatic sandwich ELISA was used to detect serum GM in 4 groups of cats; Group 1 (URT aspergillosis) - confirmed URT aspergillosis (n=13, sinonasal aspergillosis (SNA) n=6 and sino-orbital aspergillosis (SOA) n=7), Group 2 (URT other) - other URT diseases (n=15), Group 3 (β-lactam) - cats treated with β-lactam antibiotics for non-respiratory tract disease (n=14), Group 4a - healthy young cats (≤ 1 y of age, n=28), Group 4b - healthy adult cats (>1 y of age, n=16). One cat with SNA and two cats with SOA caused by an Aspergillus fumigatus-mimetic species, tested positive for serum GM. For a cut-off optical density index of 1.5, the overall sensitivity and specificity of the assay was 23% and 78% respectively. False positive results occurred in 29% of cats in Group 3 and 32% of cats in Group 4a. Specificity increased to 90% when Groups 3 and 4a were excluded from the analysis. Overall, serum GM measurement has a poor sensitivity but is a moderately specific, non-invasive screening test to rule out infection in patients with suspected feline upper respiratory tract aspergillosis.

Systematic review and meta-analysis of detecting galactomannan in bronchoalveolar lavage fluid for diagnosing invasive aspergillosis

BACKGROUND

Bronchoalveolar lavage (BAL) galactomannan (GM) assay has been used for diagnosing invasive aspergillosis (IA). We aimed to derive a definitive estimate of the overall accuracy of BAL-GM for diagnosing IA.

METHODS AND RESULTS

We undertook a systematic review of thirty diagnostic studies that evaluated the BAL-GM assay for diagnosing IA. PubMed and CBM (China Biological Medicine Database) databases were searched for relevant studies published in all languages up until Feb 2012. The pooled diagnostic odds ratio (DOR) and summary receiver operating characteristic (SROC) were constructed for each cutoff value. Additionally, pooled sensitivity (SEN), specificity (SPE), and positive and negative likelihood ratios (PLR and NLR, respectively) were calculated for summarizing overall test performance. Thirty studies were included in this meta-analysis. The summary estimates of pooled DOR, SEN, SPE, PLR, and NLR of the BAL-GM assay (cutoff value 0.5) for proven or probable IA were 52.7 (95% confidence interval (CI) 31.8-87.3), 0.87 (95% CI 0.79-0.92), 0.89 (95% CI 0.85-0.92), 8.0 (95% CI 5.7-11.1) and 0.15 (95% CI 0.10-0.23) respectively. The SROC was 0.94 (95% CI 0.92-0.96). Compared with cutoff value of 0.5, it has higher DOR, SPE and PLR, and similar SEN and NLR with cutoff value of 1.0, which indicated the optimal cutoff value might be 1.0. Compared with BAL-GM, serum GM has a lower SEN and higher SPE, while PCR displays a lower SEN and a similar SPE.

CONCLUSION

With the optimal cutoff value of 1.0, the BAL-GM assay has higher SEN compared to PCR and serum GM test. It is a useful adjunct in the diagnosis of proven and probable IA.

Detection of urinary excreted fungal galactomannan-like antigens for diagnosis of invasive aspergillosis

Mortality associated with invasive aspergillosis (IA) remains high, partly because of delayed diagnosis. Detection of microbial exoantigens, released in serum and other body fluids during infection, may help timely diagnosis. In course of IA, Aspergillus galactomannan (GM), a well established polysaccharide biomarker, is released in body fluids including urine. Urine is an abundant, safely collected specimen, well-suited for point-of-care (POC) testing, which could play an increasing role in screening for early disease. Our main objective was to demonstrate GM antigenuria as a clinically relevant biological phenomenon in IA and establish proof-of-concept that it could be translated to POC diagnosis. Utilizing a novel IgM monoclonal antibody (MAb476) that recognizes GM-like antigens from Aspergillus and other molds, we demonstrated antigenuria in an experimental animal IA model (guinea pig), as well as in human patients. In addition, we investigated the chemical nature of the urinary excreted antigen in human samples, characterized antigen detection in urine by immunoassays, described a putative assay inhibitor in urine, and indicated means of alleviation of the inhibition. We also designed and used a lateral flow immunochromatographic assay to detect urinary excreted antigen in a limited number of IA patient urine samples. In this study, we establish that POC diagnosis of IA based on urinary GM detection is feasible. Prospective studies will be necessary to establish the performance characteristics of an optimized device and define its optimal clinical use.

Role of galactomannan determinations in bronchoalveolar lavage fluid samples from critically ill patients with chronic obstructive pulmonary disease for the diagnosis of invasive pulmonary aspergillosis: a prospective study

INTRODUCTION

Critically ill chronic obstructive pulmonary disease (COPD) patients are at particular risk of invasive pulmonary aspergillosis (IPA). Our aims were to determine whether bronchoalveolar lavage fluid (BALF) galactomannan (GM) has a higher sensitivity and specificity than serum GM or lower respiratory tract (LRT) sample culture. Furthermore, we aimed to investigate what the optimal cut-off value would be for BALF GM.

METHODS

In this prospective single-center study, BALF and serum samples were collected from critically ill COPD patients on the first day of their intensive care unit admission.

RESULTS

Of 50 critically ill COPD patients admitted, BALF and serum samples were collected in 34 patients. According to the receiver operating characteristics (ROC) curve, an optical density (OD) ratio of 0.8 was chosen as the cut-off value for GM in BALF. Compared to serum GM and LRT Aspergillus isolation, BALF GM yield a better sensitivity, specificity, positive and negative predictive values of 88.9%, 100%, 100% and 94.4%, respectively. Areas under the ROC curve were 0.912 (95%CI, 0.733 to 0.985) for BALF GM, and 0.879 (95%CI, 0.691 to 0.972) for serum GM results from the first day of ICU admission. Pairwise comparison of ROC curves showed P = 0.738. The OD ratio of BALF GM in IPA patients were significantly higher than those of non-IPA patients (2.88 ± 2.09 versus 0.49 ± 0.19, P = 0.009), and the OD ratio of BALF GM was significantly higher than serum GM in IPA patients (2.88 ± 2.09 versus 0.87 ± 0.47, P = 0.023). Positive BALF GM was seen earlier than LRT secretion culture (1 day versus 3.8 days).

CONCLUSIONS

Compared to serum GM and LRT Aspergillus isolation, BALF GM seems to have a better sensitivity in the diagnosis of IPA in critically ill COPD patients. The ROC curve suggests a possible cut-off value of 0.8 for GM from BALF specimens in critically ill COPD patients.

Rapid detection and identification of Aspergillus from lower respiratory tract specimens by use of a combined probe-high-resolution melting analysis

Diagnosis of invasive aspergillosis (IA) requires increasingly rapid molecular methods that enable sensitive detection and discrimination between species. We designed and evaluated a real-time PCR-based method that combined melting temperature (T(m)) calling analysis of a specific probe with high-resolution melting analysis of the full amplicon. The test correctly identified 78 isolates of Aspergillus section Fumigati and non-Fumigati sections of Aspergillus with a limit of detection of 10(2) conidia/ml (10(2) fg/ml). No cross-reactivity with other fungi was found. The assay was further validated on lower respiratory tract specimens containing Aspergillus or not. It successfully identified Aspergillus to section level in 56 of 59 specimens. With culture as the gold standard, our assay shows 100% sensitivity and specificity and constitutes an efficient alternative for identification of Aspergillus in lower respiratory tract samples.

Serologic testing for aspergillosis in commercial broiler chickens and turkeys

Sera samples from commercial broiler chickens and turkeys diagnosed with respiratory and disseminated aspergillosis were tested for the presence of antigen and antibody to Aspergillus. Antigen detection consisted of testing for two cell-wall components, beta-glucan and galactomannan, which have been used extensively in human medicine. There were significantly higher levels of galactomannan in all broiler chicken submissions (100%) and antibody to Aspergillus in 6 out of 9 submissions (66.6%) vs. control birds. Beta-glucan analyses did not show any differences among levels in the broiler chicken groups. There were significantly higher levels of galactomannan antigen in 4 out of 7 submissions (57.1%) of aspergillosis in commercial turkeys, while only 2 out of 7 submissions (28.5%) had higher levels of antibody to Aspergillus vs. the control group. This study shows that diagnosis of respiratory and disseminated aspergillosis may be performed by detection of galactomannan antigenemia and antibodies in broiler chickens and to an extent in turkeys.

A novel extraction method combining plasma with a whole-blood fraction shows excellent sensitivity and reproducibility for patients at high risk for invasive aspergillosis

Diagnosis of invasive aspergillosis (IA) is still a major problem in routine clinical practice. Early diagnosis is essential for a good patient prognosis. PCR is a highly sensitive method for the detection of nucleic acids and could play an important role in improving the diagnosis of fungal infections. Therefore, a novel DNA extraction method, ultraclean production (UCP), was developed allowing purification of both cellular and cell-free circulating fungal DNA. In this prospective study we evaluated the commercially available UCP extraction system and compared it to an in-house system. Sixty-three patients at high risk for IA were screened twice weekly, and DNA extracted by both methods was cross-analyzed, in triplicate, by two different real-time PCR assays. The negative predictive values were high for all methods (94.3 to 100%), qualifying them as screening methods, but the sensitivity and diagnostic odds ratios were higher using the UCP extraction method. Sensitivity ranged from 33.3 to 66.7% using the in-house extracts to 100% using the UCP extraction method. Most of the unclassified patients showed no positive PCR results; however, single-positive PCR replicates were observed in some cases. These can bear clinical relevance but should be interpreted with additional clinical and laboratory data. The PCR assays from the UCP extracts showed greater reproducibility than the in-house method for probable IA patients. The standardized UCP extraction method yielded superior results, with regard to sensitivity and reproducibility, than the in-house method. This was independent of the PCR assay used to detect fungal DNA in the sample extracts.

Early serum galactomannan trend as a predictor of outcome of invasive aspergillosis

The monitoring and prediction of treatment responses to invasive aspergillosis (IA) are difficult. We determined whether serum galactomannan index (GMI) trends early in the course of disease may be useful in predicting eventual clinical outcomes. For the subjects recruited into the multicenter Global Aspergillosis Study, serial GMIs were measured at baseline and at weeks 1, 2, and 4 following antifungal treatment. Clinical response and survival at 12 weeks were the outcome measures. GMI trends were analyzed by using the generalized estimation equation approach. GMI cutoffs were evaluated by using receiver-operating curve analyses incorporating pre- and posttest probabilities. Of the 202 study patients diagnosed with IA, 71 (35.1%) had a baseline GMI of ≥ 0.5. Week 1 GMI was significantly lower for the eventual responders to treatment at week 12 than for the nonresponders (GMIs of 0.62 ± 0.12 and 1.15 ± 0.22, respectively; P = 0.035). A GMI reduction of >35% between baseline and week 1 predicted a probability of a satisfactory clinical response. For IA patients with pretreatment GMIs of <0.5 (n = 131; 64.9%), GMI ought to remain low during treatment, and a rising absolute GMI to >0.5 at week 2 despite antifungal treatment heralded a poor clinical outcome. Here, every 0.1-unit increase in the GMI between baseline and week 2 increased the likelihood of an unsatisfactory clinical response by 21.6% (P = 0.018). In summary, clinical outcomes may be anticipated by charting early GMI trends during the first 2 weeks of antifungal therapy. These findings have significant implications for the management of IA.

Immunoproteomics based identification of thioredoxin reductase GliT and novel Aspergillus fumigatus antigens for serologic diagnosis of invasive aspergillosis

Background

There has been a rising incidence of invasive aspergillosis (IA) in critically ill patients, even in the absence of an apparent predisposing immunodeficiency. The diagnosis of IA is difficult because clinical signs are not sensitive and specific, and serum galactomannan has relatively low sensitivity in this group of patients. Therefore, more prompt and accurate disease markers for early diagnosis are needed. To establish disease markers demands a thorough knowledge of fungal antigens which may be detected in the serum or other body fluids of patients. Herein we report novel immunodominant antigens identified from extracellular proteins of Aspergillus fumigatus.

Results

Extracellular proteins of A. fumigatus were separated by two-dimensional electrophoresis (2-DE) and probed with the sera from critically ill patients with proven IA. The immunoreactive protein spots were identified by MALDI-TOF mass spectrometry (MALDI-TOF -MS). Forty spots from 2DE gels were detected and 17 different proteins were identified as immunogenic in humans. Function annotation revealed that most of these proteins were metabolic enzymes involved in carbohydrate, fatty acid, amino acid, and energy metabolism. One of the proteins, thioredoxin reductase GliT (TR), which showed the best immunoactivity, was analyzed further for secretory signals, protein localization, and homology. The results indicated that TR is a secretory protein with a signal sequence exhibiting a high probability for secretion. Furthermore, TR did not match any human proteins, and had low homology with most other fungi. The recombinant TR was recognized by the sera of all proven IA patients with different underlying diseases in this study.

Conclusions

The immunoreactive proteins identified in this study may be helpful for the diagnosis of IA in critically ill patients. Our results indicate that TR and other immunodominant antigens have potential as biomarkers for the serologic diagnosis of invasive aspergillosis.

Clinical utility and prognostic value of galactomannan in neutropenic patients with invasive aspergillosis

Invasive aspergillosis (IA) is a major cause of morbidity and mortality in profoundly neutropenic patients. Delayed diagnosis and therapy may lead to poor outcomes.

AIMS

The objective of this study was to assess the performance characteristics of the galactomannan (GM) assay in serum and bronchoalveolar lavage specimens for the diagnosis of IA in neutropenic patients with hematological malignancies. We also evaluated the prognostic outcome.

PATIENTS AND METHODS

A total of 1198 serum samples and 42 BAL from 235 neutropenic patients were tested with a GM elisa platelia test. We used Cox modeling of time to 6- and 12-week mortality for GM level at the time of diagnosis (GM0) and GM decay in the week following diagnosis in proven and probable IA patients with more than two GM values.

RESULTS

There were three proven, 55 probable, and four possible cases of IA. The sensitivity and specificity of the GM test were 96.8% and 82.4% respectively. In BAL samples, sensitivity was 86% and the specificity 93%. BAL GM was more sensitive than microscopy (22.2%) and BAL culture (38.9%). Among patients with proven/probable IA, serum and BAL GM were in agreement for 92.8% of paired samples. The hazard ratio (HR) of GM0 and 1-week GM decay per unit increase in Aspergillus enzyme immunoassay (EIA) was 1.044 (95% CI, 0.738 to 1.476) and 0.709 (95% CI, 0.236 to 2.130) respectively.

CONCLUSION

We found good correlation between the GM0 and GM decay combination and outcome of IA patients. The GM is a useful tool for diagnosis and monitoring of IA.

Hyphal growth in human fungal pathogens and its role in virulence

Most of the fungal species that infect humans can grow in more than one morphological form but only a subset of pathogens produce filamentous hyphae during the infection process. This subset is phylogenetically unrelated and includes the commonly carried yeasts, Candida albicans, C. dubliniensis, and Malassezia spp., and the acquired pathogens, Aspergillus fumigatus and dermatophytes such as Trichophyton rubrum and T. mentagrophytes. The primary function of hypha formation in these opportunistic pathogens is to invade the substrate they are adhered to, whether biotic or abiotic, but other functions include the directional translocation between host environments, consolidation of the colony, nutrient acquisition and the formation of 3-dimensional matrices. To support these functions, polarised hyphal growth is co-regulated with other factors that are essential for normal hypha function in vivo.

Diagnosis of invasive aspergillosis by a commercial real-time PCR assay for Aspergillus DNA in bronchoalveolar lavage fluid samples from high-risk patients compared to a galactomannan enzyme immunoassay

Culture-independent molecular techniques such as real-time PCRs offer the potential for early diagnosis of invasive aspergillosis (IA), thereby reducing the disease-associated mortality rate. PCR-based testing is presently excluded from disease-defining consensus criteria due to lack of standardization and clinical validation. A single-center prospective study was conducted to investigate the performance of the commercially available MycAssay Aspergillus test for detecting Aspergillus DNA in patients with suspicion of IA. To this end, a total of 158 bronchoalveolar lavage (BAL) fluid specimens that were consecutively collected from hematology (n = 68) and intensive care unit (n = 90) patients were examined. Sixteen of 17 (94.1%) specimens from patients with proven/probable IA were MycAssay positive, and 15 of these 16 patients were also positive by an "in-house" PCR assay. A total of 139 of 141 (98.6%) specimens from patients without proven/probable IA were MycAssay negative. Fifteen of 16 (94.1%) MycAssay-positive patients were also positive for BAL fluid galactomannan (GM) at an index cutoff of ≥1.0 (index range, 1.1 to 8.3), as were 3 patients without IA but with pulmonary fusariosis. Interestingly, in seven of the PCR-positive BAL specimens that tested culture positive for Aspergillus species, cycle threshold values were earlier than those of specimens with a culture-negative result. In conclusion, the MycAssay Aspergillus PCR appears to be a sensitive and specific molecular test for the diagnosis of IA, and its performance is comparable to that of the GM assay. However, more large studies are necessary to firmly establish its clinical utility in high-risk settings.

Influence of dietary ingredients on in vitro inflammatory response of intestinal porcine epithelial cells challenged by an enterotoxigenic Escherichia coli (K88)

Enterotoxigenic Escherichia coli (ETEC) K88 is the main bacterial cause of diarrhea in piglets around weaning and the adhesion of ETEC to the intestinal mucosa is a prerequisite step for its colonization. In this study, the adhesion of a fimbriated ETEC and a non-fimbriated E. coli (NFEC) to the intestinal cells and the activation of the innate immune system were evaluated using a porcine intestinal epithelial cell line (IPEC-J2). The impact of several feedstuffs (wheat bran (WB); casein glycomacropeptide (CGMP); mannan-oligosaccharides (MOS); locust bean extract (LB) and Aspergillus oryzae fermentation extract (AO)) on ETEC attachment and the inflammatory response were also studied. The gene expression of TLR-4; TLR-5; IL-1β; IL-8; IL-10 and TNF-α were quantified using Cyclophilin-A, as a reference gene, and related to a non-challenged treatment. The fimbriated strain was markedly better than the non-fimbriated strain at adherence to intestinal cells and inducing an inflammatory response. All the feedstuffs studied were able to reduce the adhesion of ETEC, with the greatest decrease with CGMP or MOS at highest concentration. Regarding the inflammatory response, the highest dose of WB promoted the lowest relative expression of cytokines and chemokines. All tested feedstuffs were able to reduce the adhesion of ETEC to IPEC-J2 and interfere on the innate inflammatory response; however WB should be further studied according to the beneficial results on the intestinal inflammatory process evidenced in this study.

Diagnosis of invasive fungal infections in hematology and oncology--guidelines from the Infectious Diseases Working Party in Haematology and Oncology of the German Society for Haematology and Oncology (AGIHO)

Invasive fungal infections (IFIs) are a primary cause of morbidity and mortality in patients with hematological malignancies. Establishing a definite diagnosis of IFI in immunocompromised patients is particularly challenging and time consuming, but delayed initiation of antifungal treatment increases mortality. The limited overall outcome has led to the strategy of initiating either 'empirical' or 'preemptive' antifungal therapy before the final diagnosis. However, diagnostic procedures have been vastly improved in recent years. Particularly noteworthy is the introduction of newer imaging techniques and non-culture methods, including antigen-based assays, metabolite detection and molecular detection of fungal DNA from body fluid samples. Though varying widely in cancer patients, the risk of IFI is highest in those with allogeneic stem cell transplantation and those with acute leukemia. The AGIHO presents recommendations for the diagnosis of IFIs with risk-adapted screening concepts for febrile episodes in patients with haemato-oncological disorders.

Serum and bronchoalveolar lavage fluid galactomannan assays in patients with pulmonary aspergilloma

The sensitivities of the serum and bronchoalveolar lavage galactomannan (GM) assays in 48 patients with pulmonary aspergilloma were 38% (13 of 34; 95% confidence interval [CI], 22%-56%) and 92% (33 of 36; 95% CI, 78%-98%), respectively. The positivity of serum GM assays was significantly higher in patients with hemoptysis than in those without hemoptysis (52% vs 9%; P=.02).

Advances and prospects for molecular diagnostics of fungal infections

The polymerase chain reaction (PCR) methods published for the diagnosis of invasive fungal infections are still not included in the revised European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) Consensus Group definitions of IA. This could be achieved with consensual PCR procedures. A checklist of items has been proposed to improve the reliability of the results and clinicians' confidence in them, with emphasis on limiting false-positive results from contamination with either previously amplified products or environmental commensals. Internal amplification controls are mandatory to expose false-negative results. However, our ignorance of the origin and the kinetics of fungal DNA during an infection hamper the choice of the best specimen and DNA extraction protocol. Evidence is increasing that serum could be a good compromise between sensitivity and ease of DNA extraction. Once a technical consensus is achieved, clinical studies should be initiated to integrate quantitative PCR in the diagnostic armamentarium.

[Update: invasive fungal infections: Diagnosis and treatment in surgical intensive care medicine]

Fungal infections are of great relevance in surgical intensive care and Candida species represent the predominant part of fungal pathogens. Invasive aspergillosis is also relevant especially in patients with chronic pulmonary diseases. It is crucial for therapy success to begin adequate antifungal treatment at an early stage of the disease. Risk stratification of individual patient symptoms is essential for therapy timing. In case of suspected or proven candida infection, fluconazole is the agent of choice when the patient is clinically stable and no azoles have been administrated in advance and the local epidemiology makes azol resistance unlikely. For clinically instable patients with organ dysfunction the echinocandins serve as primary therapy because of their broad spectrum and reasonable safety profile. Due to a relevant proportion of azole resistant Candida species, susceptibility testing should be done routinely. Depending on the species detected de-escalating to an azole is feasible if organ dysfunctions have resolved. An invasive aspergillosis is primarily treated with voriconazole.

Invasive Myceliophthora thermophila infection mimicking invasive aspergillosis in a neutropenic patient: a new cause of cross-reactivity with the Aspergillus galactomannan serum antigen assay

Myceliophthora thermophila is a thermophilic mould widely found in the environment but rarely responsible for human infections. We describe a case of invasive Myceliophthora thermophila infection mimicking invasive aspergillosis in a neutropenic patient with haematological malignancy. Cross-reactivity with Aspergillus galactomannan assay (GM) was demonstrated by repeated positive results and confirmed by cross-reaction between the fungal isolate and the GM assay. The patient was successfully treated with voriconazole. Potential GM cross-reactivity must be considered in future studies including patients categorized as having probable invasive aspergillosis using the GM as the only mycological criterion.

Performance of the new Platelia Candida Plus assays for the diagnosis of invasive Candida infection in patients undergoing myeloablative therapy

The performance of the new Platelia Candida Antigen Plus (Ag Plus) and Antibody Plus (Ab Plus) assays (Biorad Laboratories, France) was evaluated using a collection of serum samples obtained from 21 patients with microbiologically proven invasive candidiasis and 30 control patients who were being treated with myeloablative chemotherapy, and the data compared with that obtained with the earlier version of the Platelia Candida assays (Ag and Ab), and 1,3-ß-D-glucan (BG) detection systems. The sensitivity of the Ag Plus and Ab Plus assays in the per patient analysis ranged from 55-70% and from 30-64% for patients with less than 15 days of neutropenia and more than 15 days of neutropenia, respectively. Sensitivity and time to detection of these new assays was not significantly better than of the conventional Platelia Candida tests. However, the specificity of the Ag-Plus assay was reduced by approximately 50% as compared to the Ag assay. Logistic regression analysis showed that this was probably due to the fact that circulating mannan was also being detected by the Ag Plus assay in patients with superficial candidiasis. Further studies are needed to confirm our results and to determine the place of the Platelia Ag Plus and Ab Plus assays in the management of haematology patients at risk for Candida infections.

Design issues in a randomized controlled trial of a pre-emptive versus empiric antifungal strategy for invasive aspergillosis in patients with high-risk hematologic malignancies

Invasive aspergillosis (IA) is a major cause of mortality in patients with hematological malignancies, due largely to the inability of traditional culture and biopsy methods to make an early or accurate diagnosis. Diagnostic accuracy studies suggest that Aspergillus galactomannan (GM) enzyme immunoassay (ELISA) and Aspergillus PCR-based methods may overcome these limitations, but their impact on patient outcomes should be evaluated in a diagnostic randomized controlled trial (D-RCT). This article describes the methodology of a D-RCT which compares a new pre-emptive strategy (GM-ELISA- and Aspergillus PCR-driven antifungal therapy) with the standard fever-driven empiric antifungal treatment strategy. Issues including primary end-point and patient selection, duration of screening, choice of tests for the pre-emptive strategy, antifungal prophylaxis and bias control, which were considered in the design of the trial, are discussed. We suggest that the template presented herein is considered by researchers when evaluating the utility of new diagnostic tests (ClinicalTrials.gov number, NCT00163722).

Antifungal treatment strategies in patients with haematological diseases or cancer: from prophylaxis to empirical, pre-emptive and targeted therapy

Immunocompromised patients have a high risk for invasive fungal diseases (IFDs). These infections are mostly life-threatening and an early diagnosis and initiation of appropriate antifungal therapy are essential for the clinical outcome. Empirical treatment is regarded as the standard of care for granulocytopenic patients who remain febrile despite broad-spectrum antibiotics. However, this strategy can bear a risk of overtreatment and subsequently induce toxicities and unnecessary treatment costs. Pre-emptive antifungal therapy is now increasingly used to close the time gap between delayed initiation for proven disease and empirical treatment for anticipated infection without further laboratory or radiological evidence of fungal disease. Currently, some new non-invasive microbiological and laboratory methods, like the Aspergillus-galactomannan sandwich-enzyme immunoassay (Aspergillus GM-ELISA), 1,3-β-D-glucan assay or PCR techniques have been developed for a better diagnosis and determination of target patients. The current diagnostic approaches to fungal infections and the role of the revised definitions for invasive fungal infections, now IFDs, will be discussed in this review as well as old and emerging approaches to empirical, pre-emptive and targeted antifungal therapies in patients with haemato-oncological malignancies.

Clinical practice guideline for the use of antimicrobial agents in neutropenic patients with cancer: 2010 update by the infectious diseases society of america

This document updates and expands the initial Infectious Diseases Society of America (IDSA) Fever and Neutropenia Guideline that was published in 1997 and first updated in 2002. It is intended as a guide for the use of antimicrobial agents in managing patients with cancer who experience chemotherapy-induced fever and neutropenia. Recent advances in antimicrobial drug development and technology, clinical trial results, and extensive clinical experience have informed the approaches and recommendations herein. Because the previous iteration of this guideline in 2002, we have a developed a clearer definition of which populations of patients with cancer may benefit most from antibiotic, antifungal, and antiviral prophylaxis. Furthermore, categorizing neutropenic patients as being at high risk or low risk for infection according to presenting signs and symptoms, underlying cancer, type of therapy, and medical comorbidities has become essential to the treatment algorithm. Risk stratification is a recommended starting point for managing patients with fever and neutropenia. In addition, earlier detection of invasive fungal infections has led to debate regarding optimal use of empirical or preemptive antifungal therapy, although algorithms are still evolving. What has not changed is the indication for immediate empirical antibiotic therapy. It remains true that all patients who present with fever and neutropenia should be treated swiftly and broadly with antibiotics to treat both gram-positive and gram-negative pathogens. Finally, we note that all Panel members are from institutions in the United States or Canada; thus, these guidelines were developed in the context of North American practices. Some recommendations may not be as applicable outside of North America, in areas where differences in available antibiotics, in the predominant pathogens, and/or in health care-associated economic conditions exist. Regardless of venue, clinical vigilance and immediate treatment are the universal keys to managing neutropenic patients with fever and/or infection.

Real-time PCR and quantitative culture for monitoring of experimental Aspergillus fumigatus intracranial infection in neutropenic mice

The central nervous system (CNS) is the most common site of dissemination during Aspergillus infection. PCR has the potential to facilitate early diagnosis of CNS aspergillosis, which could assist in reducing disease mortality. In two experiments, neutropenic CD-1 male mice were infected intracranially with 5×10⁶ conidia of Aspergillus fumigatus. At time points up to 120 h after infection, mice were euthanized and samples of blood, brain, spinal cord and cerebrospinal fluid (CSF) were taken. The brain fungal burden was determined by quantitative culture, and fungal DNA was detected by quantitative PCR. Plating for A. fumigatus from the brain confirmed that all mice had burdens of log₁₀>3 from 4 to 120 h after infection. A. fumigatus DNA was detected in blood (88 %), brain (96 %), CSF (52 %) and spinal cord (92 %) samples. The brain and spinal cord contained the highest concentrations of fungal DNA. Adapting the extraction protocol to maximize yield from small sample volumes (10 µl CSF or 200 µl blood) allowed PCR detection of A. fumigatus in infected mice, suggesting the use of CSF and blood as diagnostic clinical samples for CNS aspergillosis.

Invasive fungal infections in liver transplantation

Invasive fungal infections (IFIs) in immunocompromised patients, particularly liver transplant recipients, are the subject of increasing clinical attention. Although the overall incidence of fungal infections in liver transplant recipients has declined due to the early treatment of high-risk patients, the overall mortality rate remains high, particularly for invasive candidiasis and aspergillosis. IFIs after liver transplantation are strongly associated with negative outcomes, increasing the cost to recipients. Numerous studies have attempted to determine the independent risk factors related to IFIs and to reduce the morbidity and mortality with empirical antifungal prophylaxis after liver transplantation. Unfortunately, fungal infections are often diagnosed too late; symptoms can be mild and non-specific even with dissemination. Currently, no consensus exists on which patients should receive antifungal prophylaxis, when prophylaxis should be given, which antifungal agents should be used, and what duration is effective. This review highlights the types of IFI, risk factors, diagnosis, antifungal prophylaxis, and treatment after liver transplantation. With the early identification of patients at high risk for IFIs and the development of new molecular diagnostic techniques for early detection, the role of antifungal compounds in fungal infection prophylaxis needs to be established to improve the survival rate and quality of life in liver transplant patients.

Executive Summary: Clinical Practice Guideline for the Use of Antimicrobial Agents in Neutropenic Patients with Cancer: 2010 Update by the Infectious Diseases Society of America

This document updates and expands the initial Infectious Diseases Society of America (IDSA) Fever and Neutropenia Guideline that was published in 1997 and first updated in 2002. It is intended as a guide for the use of antimicrobial agents in managing patients with cancer who experience chemotherapy-induced fever and neutropenia.

Recent advances in antimicrobial drug development and technology, clinical trial results, and extensive clinical experience have informed the approaches and recommendations herein. Because the previous iteration of this guideline in 2002, we have a developed a clearer definition of which populations of patients with cancer may benefit most from antibiotic, antifungal, and antiviral prophylaxis. Furthermore, categorizing neutropenic patients as being at high risk or low risk for infection according to presenting signs and symptoms, underlying cancer, type of therapy, and medical comorbidities has become essential to the treatment algorithm. Risk stratification is a recommended starting point for managing patients with fever and neutropenia. In addition, earlier detection of invasive fungal infections has led to debate regarding optimal use of empirical or preemptive antifungal therapy, although algorithms are still evolving.

What has not changed is the indication for immediate empirical antibiotic therapy. It remains true that all patients who present with fever and neutropenia should be treated swiftly and broadly with antibiotics to treat both gram-positive and gram-negative pathogens.

Finally, we note that all Panel members are from institutions in the United States or Canada; thus, these guidelines were developed in the context of North American practices. Some recommendations may not be as applicable outside of North America, in areas where differences in available antibiotics, in the predominant pathogens, and/or in health care–associated economic conditions exist. Regardless of venue, clinical vigilance and immediate treatment are the universal keys to managing neutropenic patients with fever and/or infection.

Ribosomal and mitochondrial DNA target for real-time PCR diagnosis of invasive aspergillosis

The aim of the present study was to assess the diagnostic efficacy of a combination of two quantitative Aspergillus PCR assays, targeting a mitochondrial and a ribosomal target, in patients with risk factors for invasive aspergillosis (IA) and positive galactomannan (GM) antigen. Forty-four patients with hematological malignancies and risk factors for IA according to revised European Organization for Research on Treatment of Cancer and the Mycoses Study Group criteria (EORTC/MSG) criteria and presenting at least two sequential GM-positive sera were included in the study. Mitochondrial PCR was carried out prospectively on all GM-positive serum samples. Ribosomal PCR was carried out retrospectively on frozen stored sera. The sensitivities of mitochondrial and ribosomal PCRs were 58% and 50%, respectively. The diagnostic test performance was improved by using a combination of both PCR assays and by considering a patient PCR positive when at least two positive results were obtained. The sensitivity, specificity, and positive and negative likelihood ratios were 65%, 94%, and 11.8 and 0.37, respectively. A significant association between fatal outcome at 90 days and positive results of ribosomal PCR assays was observed (adjusted hazard ratio = 8.2; 95% confidence interval [CI] = 1.0 to 65.8; P = 0.048). Our results showed that the combination of two PCR assays targeting mitochondrial and ribosomal Aspergillus DNA improves the sensitivity of PCR in the diagnosis of IA in hematological patients with risk factors and positive GM results. This study also confirms that a positive PCR result is associated with a poor prognosis in these patients and should lead to specific antifungal therapy being introduced immediately.