Use of the Pastorex aspergillus antigen latex agglutination test for the diagnosis of invasive aspergillosis

Invasive aspergillosis in liver transplant recipients: epidemiology, clinical characteristics, treatment, and outcomes in 116 cases

Invasive aspergillosis (IA) in liver transplant recipients is associated with grave outcomes. We reviewed 116 individual cases reported in the literature from 1985 to 2013. IA was diagnosed after a median of 25 days after transplantation and involved a single organ in 51% of the cases, whereas in the remaining cases, multiple sites were involved. The most common infecting Aspergillus species were Aspergillus fumigatus (73%), Aspergillus flavus (14%), and Aspergillus terreus (8%). Amphotericin B was the drug most frequently used, and it was followed by voriconazole and itraconazole. Combination regimens were used in 51% of the cases. The overall 1-year cumulative survival probability was 35% [95% confidence interval (CI) = 24.6%-49.6%]. Survival was significantly higher for patients reported from the year 2000 and thereafter (P < 0.001), for those diagnosed with IA more than 30 days after transplantation versus those diagnosed earlier (P = 0.019), and for patients without renal failure (P = 0.020). Additionally, the use of voriconazole was significantly associated with a higher probability of survival (P < 0.001). Cox regression analysis showed that subjects with the involvement of multiple sites had a 2.52 times higher risk of a negative outcome (95% CI = 1.08-5.87) than those with the involvement of a single site. Thus, IA causes life-threatening infections in liver transplant recipients. Predictors associated with poor outcomes may help clinicians to optimize the management of this infection.

A comparison of galactomannan-ELISA and a newly developed galactomannan-LATEX test in the serologic diagnosis of invasive aspergillosis in patients with hematologic malignancies

We compared the sensitivity and specificity of galactomannan enzyme-linked immunosorbent assay (GM-ELISA) with that of a newly developed version of the commercially available latex agglutination test (GM-LATEX) in our patient population. Serum samples were collected from 144 healthy adult donors (controls); another 17 consecutive hematologic malignancy (HM) patients with probable or proven invasive aspergillosis (IA) were tested. Clinical, microbiological, and pathological data were obtained. The sensitivity of the GM-LATEX test was 53% per patient and 66% per sample and that of the GM-ELISA test was 41% per patient and 21% per sample. Both tests demonstrated a specificity of 99%. The GM-LATEX test demonstrated a superior sensitivity in terms of detecting galactomannan and thus may be useful in the diagnosis of IA in patients with HM.

Update on the contribution of galactomannan for the diagnosis of invasive aspergillosis

The diagnosis of invasive fungal infections (IFI) remains a challenge, particularly for diseases caused by filamentous fungi such as Aspergillus species. Unfortunately, many patients affected by these conditions are not identified before autopsy. Therefore, there is a need for new diagnostic methods for IFI. Galactomannan is a soluble antigen released during hyphal growth in tissues. A commercially available sandwich ELISA assay that detects galactomannan has been used in Europe for many years and is now approved for use in the USA. The test has an excellent negative predictive value in the detection of invasive aspergillosis (IA) in high-risk patients. In addition, it is more sensitive than culture and allows IA to be diagnosed before clinical manifestations occur. However, false-negative and false-positive results in certain populations are the main limitations to its use. The purpose of this review is to summarize the current knowledge about galactomannan testing in patients at risk for IA.

Evaluation of peptone glucose fluconazole agar as a selective medium for rapid and enhanced isolation of Aspergillus fumigatus from the respiratory tract of bronchopulmonary aspergillosis patients colonized by Candida albicans

We have reported earlier that Aspergillus fumigatus is inhibited in vitro by Candida albicans which also interferes in its isolation from sputum experimentally seeded with predetermined graded inocula of the two fungi. It was further shown that this interference was neutralized by employing peptone glucose agar with incorporation of fluconazole which is more inhibitory to C. albicans than to A. fumigatus. This communication embodies the results of evaluation of peptone glucose fluconazole agar (PGFA) as a selective culture medium for rapid and enhanced isolation of A. fumigatus from sputum of patients clinically suspected of aspergillosis with C. albicans colonization in the respiratory tract. Of the 23 sputum specimens and one broncho-alveolar lavage collected from 15 suspected aspergillosis patients, A. fumigatus was isolated from all (100%) on PGFA as against only 19 specimens (79%) that proved to be positive on the control PGA medium (P<0.05). The greater efficacy of PGFA than that of PGA was further evident from the 2-fold higher A. fumigatus mean colony count (8.2+/-1.87) on the former medium than on the latter (3.7+/-1.00), and this difference was found to be statistically significant (P<0.05). Besides, A. fumigatus colonies were macroscopically recognizable within 2-3 days on PGFA at 28 degrees C in strong contrast to 5-7 days required on PGA. Based upon these observations, PGFA is recommended for wider application as a selective medium for rapid and enhanced recovery of A. fumigatus from sputum of patients clinically suspected of aspergillosis with C. albicans colonization in their respiratory tract.

Utility of Aspergillus Antigen Detection in Specimens Other than Serum Specimens

The detection of circulating galactomannan in serum is an important tool for the early diagnosis of invasive aspergillosis. A commercial enzyme-linked immunosorbent assay (Platelia Aspergillus; BioRad) was shown to be both highly sensitive and specific for detection of galactomannan in serum samples. Despite the fact that this assay is validated for serum samples, specimens of other body fluids are increasingly used for detection of galactomannan, including urine, bronchoalveolar lavage fluid, and cerebrospinal fluid. Review of the literature shows that galactomannan can be detected in each of these samples from patients with invasive aspergillosis with higher sensitivity than is the case with culture, as well as early in the course of infection. However, the evidence thus far is based on case reports--predominantly retrospective studies--that often include heterogeneous patient populations and limited numbers of cases of proven infection. Clearly, well-designed prospective studies with systematic sampling and use of consensus case definitions are needed to compare the performance of antigen detection in samples other than serum specimens with that in serum specimens.

Current status of nonculture methods for diagnosis of invasive fungal infections

The incidence of invasive fungal infections has increased dramatically in recent decades, especially among immunocompromised patients. However, the diagnosis of these infections in a timely fashion is often very difficult. Conventional microbiologic and histopathologic approaches generally are neither sensitive nor specific, and they often do not detect invasive fungal infection until late in the course of disease. Since early diagnosis may guide appropriate treatment and prevent mortality, there has been considerable interest in developing nonculture approaches to diagnosing fungal infections. These approaches include detection of specific host immune responses to fungal antigens, detection of specific macromolecular antigens using immunologic reagents, amplification and detection of specific fungal nucleic acid sequences, and detection and quantitation of specific fungal metabolite products. This work reviews the current status and recent developments as well as problems in the design of nonculture diagnostic methods for invasive fungal infections.

Use of real-time PCR on blood samples for diagnosis of invasive aspergillosis

We developed a new quantitative system for diagnosis of invasive pulmonary aspergillosis (IPA) using real-time automated polymerase chain reaction (PCR). Intra-assay and interassay precision rates for in vitro examination were 2.53% and 2.20%, respectively, and the linearity of this assay was obtained when there were >20 copies/well. We examined 323 samples taken from 122 patients with hematological malignancies, including 33 patients with IPA and 89 control patients. Blood samples were subjected to PCR antigen detection methods, using enzyme-linked immunosorbent assay (ELISA) and determination of plasma (1-->3)-beta-D-glucan (BDG) concentration. The sensitivities of PCR, ELISA, and BDG measurement for diagnosis of IPA were 79%, 58%, and 67%, respectively; the specificities were 92%, 97%, and 84%. Positive findings on PCR preceded those of computed tomography by -0.3+/-6.6 days, those of BDG measurement by 6.5+/-4.9 days, and those of ELISA by 2.8+/-4.1 days. Real-time PCR was sensitive for IPA diagnosis, and quantitation was accurate.

Aspergillus antigenemia sandwich-enzyme immunoassay test as a serodiagnostic method for invasive aspergillosis in liver transplant recipients

BACKGROUND

Invasive aspergillosis (IA) is an important cause of mortality in liver transplant patients. Clinical and microbiological diagnosis is difficult, and it is frequently achieved only after autopsy. Early diagnosis and antifungal therapy could improve the survival of these patients.

METHODS

A retrospective case-control study of IA in liver transplant recipients (OLT) was performed to determine the value of the detection of galactomannan Aspergillus antigen in serum using a sandwich-ELISA test (Platelia, Sanofi Diagnostic Pasteur). Stored frozen serum specimens obtained during the posttransplantation period were used.

RESULTS

Fourteen cases of IA were diagnosed in 240 OLT recipients (IA incidence: 5.8%) during 5 years with 13 deaths (mortality: 93%). Nine case patients and 33 control patients met the criteria required for being considered "valid" for antigenemia analysis. In five of the nine case patients, a serum sample was positive for Aspergillus antigenemia detection. The median value was 5.7 ng/ml (range: 1.6-6.6). Sensitivity of the test was 55.6%, specificity was 93.9%, the positive predictive value was 71.4%, and the negative predictive value was 88.6%. The likelihood ratio of a positive test was 9.2.

CONCLUSIONS

Galactomannan detection in serum could be useful for an early diagnosis of IA in OLT recipients.

Aspergillus antigen testing in bone marrow transplant recipients

AIMS

To assess the clinical usefulness of a commercial aspergillus antigen enzyme linked immunosorbent assay (ELISA) in the diagnosis of invasive aspergillosis (IA) in bone marrow transplant recipients, and to compare it with a commercial latex agglutination (LA) test.

METHODS

In total, 2026 serum samples from 104 bone marrow transplant recipients were tested. These comprised 67 sera from seven patients who had died with confirmed IA, 268 sera from nine patients who had died with suspected IA, and 1691 sera from 88 patients with no clinical, radiological, or microbiological signs of IA.

RESULTS

The ELISA was more sensitive than the LA test. All patients who were ELISA positive were also LA positive, and a positive LA result never preceded a positive ELISA. Twelve of 16 patients with confirmed or suspected IA were ELISA positive on two or more occasions, compared with 10 of 15 who were LA positive. ELISA was positive before LA in five patients (range, 2-14 days), and became positive on the same day in the remainder. Aspergillus antigen was detected by ELISA a median of 15 days before death (range, 4-233). Clinical and/or radiological evidence of IA was noted in all patients, and a positive ELISA was never the sole criterion for introduction of antifungal treatment. Two samples (one from each of two patients without IA) gave false positive results.

CONCLUSIONS

The aspergillus ELISA is a specific indicator of invasive aspergillosis if the criterion of two positive samples is required to confirm the diagnosis. However, the test is insufficiently sensitive to diagnose aspergillosis before other symptoms or signs are apparent, and hence is unlikely to lead to earlier initiation of antifungal treatment. It is therefore unsuitable for screening of asymptomatic patients at risk of invasive aspergillosis, but does have a useful role in confirming the diagnosis in symptomatic patients.

Comparison of commercial latex agglutination and sandwich enzyme immunoassays with a competitive binding inhibition enzyme immunoassay for detection of antigenemia and antigenuria in a rabbit model of invasive aspergillosis

A commercial latex agglutination assay (LA) and a sandwich enzyme immunoassay (SEIA) (Sanofi Diagnostics Pasteur, Marnes-la-Coquette, France) were compared with a competitive binding inhibition assay (enzyme immunoassay [EIA]) to determine the potential uses and limitations of these antigen detection tests for the sensitive, specific, and rapid diagnosis of invasive aspergillosis (IA). Toward this end, well-characterized serum and urine specimens were obtained by using a rabbit model of IA. Serially collected serum or urine specimens were obtained daily from control rabbits or from rabbits immunosuppressed and infected systemically with Aspergillus fumigatus. By 4 days after infection, EIA, LA, and SEIA detected antigen in the sera of 93, 93, and 100% of A. fumigatus-infected rabbits, respectively, whereas antigen was detected in the urine of 93, 100, and 100% of the rabbits, respectively. False-positive results for non-A. fumigatus-infected rabbits for EIA, LA, and SEIA were as follows: for serum, 14, 11, and 23%, respectively; for urine, 14, 84, and 90%, respectively. Therefore, although the sensitivities of all three tests were similar, the specificity was generally greater for EIA than for LA or SEIA. Infection was also detected earlier by EIA, by which the serum of 53% of A. fumigatus-infected rabbits was positive as early as 1 day after infection, whereas the serum of only 27% of the rabbits tested by LA was positive. Although the serum of 92% of A. fumigatus-infected rabbits was positive by SEIA as early as 1 day after infection, the serum of a high percentage (50%) was false positive before infection. The urine of 21% of A. fumigatus-infected rabbits was positive by EIA as early as 1 day after infection, and the urine of none of the rabbits was false positive before infection. When EIA results for urine specimens were combined with those for serum, sensitivity was improved (i.e., 67% of rabbits were positive by 1 day after infection and only one rabbit gave a false-positive result). A total of 93% of A. fumigatus-infected rabbits were positive for antigen in urine as early as 1 day after infection and the urine of 100% of the rabbits was positive by SEIA. However, before infection, 79% of A. fumigatus-infected rabbits were false positive for antigen in urine by LA and 90% were false positive for antigen in urine by SEIA. These data indicate that the EIA has the potential to be used to diagnose IA with both serum and urine specimens and to detect a greater number of infections earlier with greater specificity than the specificities achieved with the commercial tests.

Autopsy-controlled prospective evaluation of serial screening for circulating galactomannan by a sandwich enzyme-linked immunosorbent assay for hematological patients at risk for invasive Aspergillosis

Efforts to improve the diagnosis of invasive aspergillosis (IA) have been directed towards the detection of fungal antigens, including galactomannan (GM). However, previous evaluations of GM detection have been hampered by a lack of proven cases of IA and by a nonserial study design. This prospective study assessed the diagnostic value of serial screening for circulating GM by using a recently developed sandwich enzyme-linked immunosorbent assay (ELISA) for prolonged-neutropenic and/or steroid-treated patients with hematological disorders. Serum GM levels were monitored twice weekly for 186 consecutive patients at increased risk for IA. The patients were stratified according to the likelihood of IA (proven, probable, possible, and no evidence of IA) by using stringent criteria. Proven IA was defined by characteristic histopathological findings together with a positive culture for Aspergillus species. Autopsy and culture from autopsy specimens was used to verify both positive and negative test results. A total of 2,172 serum samples were tested from 243 episodes (mean, 9 samples/episode). Based on the analysis of 71 patients with confirmed disease status (culture and histology), the sensitivity and specificity of serial GM monitoring were 92.6 and 95.4%, respectively. The positive predictive value was almost 93%, the negative predictive value was 95%, and the efficacy was 94%. False-positive reactions occurred at a rate of nearly 8%, although this figure might have been overestimated. Less than 1% of all tested sera were considered inconclusive. In more than half of the cases, antigenemia was detected before clinical suspicion of IA (median, 6 days before). Serial determination of serum GM by the sandwich ELISA technique is a sensitive tool for the diagnosis of IA in hematological patients at risk. This approach may substantially influence clinical management with regard to preemptive and empirical antifungal therapy.

A polymerase chain reaction enzyme immunoassay for diagnosing infection caused by Aspergillus fumigatus

AIM

To develop a polymerase chain reaction enzyme immunoassay (PCR-EIA) to measure levels of circulating aspergillus DNA in invasive aspergillosis caused by Aspergillus fumigatus.

METHODS

The PCR reaction was based on primers from the 18s rRNA gene. Binding of the product to a streptavidin coated microtitration plate was mediated by a biotinylated capture probe. The product was digoxigenylated during PCR and this was the tag to which antibody was bound in the subsequent EIA.

RESULTS

The optical density (OD) endpoint was < 0.1 in 10 sera from neutropenic patients with no evidence of invasive aspergillosis, and in 10 sera from nonneutropenic patients with bacterial pneumonia (group 1). The OD from five of 12 patients with allergic bronchopulmonary aspergillosis (ABPA) (group 2), three with an aspergilloma (group 3), and five with possible invasive aspergillosis (group 4) was > or = 0.1. In 63 sera from 33 cases of proven invasive aspergillosis (group 5) an OD > or = 0.1 was achieved in 48 sera from 30 patients. The maximum OD was 0.510. The level fell in survivors and gradually rose in fatal cases.

CONCLUSIONS

This assay validated the concept of diagnosing invasive aspergillosis by measuring levels of circulating fungal DNA in serum.

Systemic mycoses during prophylactical use of liposomal amphotericin B (Ambisome) after liver transplantation

We investigated the prophylactical administration of liposomal amphotericin B (Ambisome) in the early phase after liver transplantation (LTx). Fifty-eight patients received Ambisome prophylactically after LTx. Ambisome (1 mg kg-1 day-1) was given intravenously for 7 days after LTx. Immunosuppressive prophylaxis was cyclosporin A (CsA) based in 11 patients. Forty-seven patients had a tacrolimus-based immunosuppressive regimen. CsA and tacrolimus dosages were adjusted to trough levels of 150-250 ng ml-1 (EMIT) and 5-15 ng ml-1 (MEIA II) respectively. Three patients died from sepsis due to Aspergillus fumigatus infection. Reasons for a fatal outcome were foudroyant Aspergillus pneumonia in a patient transplanted for fulminant hepatic failure on post-operative day (pod) 8; Aspergillus sepsis with severe endocardidtis in a patient with two retransplantations for graft non/dysfunction on pod 24; and disseminated aspergillosis due to Aspergillus fumigatus in a patient retransplanted for primary non-function (pod 19). All three patients underwent haemofiltration for renal failure. One patient with Candida albicans sepsis (pod 4) recovered under increased dosage of Ambisome (3 mg kg-1 per day). Ambisome (1 mg kg-1 per day) seems to be beneficial against systemic Candida infections. However, the onset of systemic Aspergillus infections could not be prevented. Obviously, higher Ambisome doses appear to be necessary against Aspergillus. We recommend the use of Ambisome (3 mg kg-1 per day) for patients with risk factors such as graft dys-/non-function, retransplantation, haemofiltration and complicated acute liver failure to prevent invasive aspergillosis.

Detection of Aspergillus fumigatus PCR products by a microtitre plate based DNA hybridisation assay

AIMS

To develop a DNA based plate hybridisation assay for the detection of polymerase chain reaction (PCR) products amplified from Aspergillus fumigatus DNA; and to determine the sensitivity of this technique and compare it with Southern blotting.

METHODS

A half-log dilution series of DNA extracted from A fumigatus was amplified with specific primers, one of which was 5' end labelled with biotin. PCR products were subsequently detected by agarose gel electrophoresis, Southern blotting, and binding of the products to a streptavidin coated microtitre well, followed by non-radioactive colorimetric detection. Amplification was carried out 10 times for each DNA dilution and a plot of initial DNA concentration against signal intensity was made.

RESULTS

A DNA concentration of 1.5 pg could be detected by agarose gel electrophoresis and Southern blotting with a non-radioactively labelled aspergillus specific probe; 1.5 pg was detectable by streptavidin binding of the PCR products to a microtitre plate. The signal from the microtitre plate detection was proportional to the amount of DNA in the PCR reaction on a log-log scale between 100 and 1 pg of DNA.

CONCLUSIONS

A DNA based plate hybridisation assay for the detection of A fumigatus PCR products is as sensitive as Southern blotting. However, results are obtained in three hours rather than the three days required for agarose gel electrophoresis, blotting, hybridisation, and detection.

Detection of antigen in sera of patients with invasive aspergillosis: intra- and interlaboratory reproducibility. The Dutch Interuniversity Working Party for Invasive Mycoses

The intra- and interlaboratory reproducibilities of a commercial sandwich enzyme-linked immunosorbent assay (ELISA) for the detection of Aspergillus galactomannan in serum (Platelia Aspergillus; Sanofi Diagnostics Pasteur, Marnes-La-Coquette, France) were evaluated in six laboratories of university hospitals. Twenty serum samples were obtained from 12 neutropenic patients including 6 with invasive aspergillosis. These samples were blinded and sent to each center together with eight blinded ELISA-negative serum samples spiked with known concentrations of galactomannan. The centers were provided with ELISA microtiter plates from a single batch and a detailed protocol. Ten clinical samples showed ELISA reactivity, while 10 samples were ELISA negative. The mean coefficient of variation (CV) of the optical density values was 4.24% within a single assay and 25.6% between runs. The interassay CV of the ratios for the serum samples tested was 18.6%. Analysis of ordinal interpretation of the ELISA result (i.e., negative, gray zone, or positive) showed excellent reproducibility. Recalculation of the cutoff values for positive and negative samples suggested that the cutoff level recommended by the manufacturer could be lowered from 1.0 to 0.8 for negative samples and from 1.5 to 1.0 for positive samples. The intra- and interlaboratory reproducibilities were excellent when the ELISA results were interpreted as ordinal data, but considerable variation in optical density values and, to a lesser extent, in the ratios for the serum samples tested, was observed between runs. High assay variability was also found for serum samples spiked with known concentrations of galactomannan. Therefore, antigen titers in serum samples from a single patient, measured in different runs, should be compared with caution.

Serum Aspergillus galactomannan antigen testing by sandwich ELISA: practical use in neutropenic patients

The double sandwich ELISA detecting Aspergillus galactomannan (GM) was prospectively evaluated for the diagnosis of invasive aspergillosis (IA) in 50 haematological patients at risk for IA. Serum samples were collected once weekly as long as the risk factors persisted. Six patients had proven or probable IA (3 A. fumigatus, 1 A. flavus, 1 A. niger, 1 A. ustus) and the GM titres were parallel to the clinical evolution of IA. Six of nine patients with suspected IA had at least two consecutive serum GM titres above 1 ng/ml and died with increasing titres, whereas the GM-negative patients survived. Positive GM titres did not anticipate the isolation of fungi. Unfortunately, positive GM titres did not anticipate the initiation of antifungal therapy, based on clinical suspicion. Moreover, if a true-positive result was defined as two consecutive positive serum samples, four patients out of 35 without proven, probable or suspected IA were positive. Then, the rate of false-positive results was high (12%) in the range previously reported. Nevertheless, the GM ELISA appears useful to assess IA and to follow the efficacy of antifungal treatment.

Guidelines for the investigation of invasive fungal infections in haematological malignancy and solid organ transplantation. British Society for Medical Mycology

Invasive fungal infections are increasing in incidence and now affect as many as 50% of neutropenic/bone marrow transplant patients and 5 to 20% of solid organ transplant recipients. Unfortunately, many of the diagnostic tests available have a low sensitivity. The guidelines presented here have been produced by a working party of the British Society for Medical Mycology in an attempt to optimise the use of these tests. The yield of fungi from blood cultures can be increased by ensuring that at least 20 ml of blood are taken for aerobic culture, by using more than one method of blood culture, and by employing terminal subculture if continuous monitoring systems are used with a five-day incubation protocol. Skin lesions in febrile neutropenic patients should be biopsied and cultured for fungi. The detection of galactomannan in blood or urine is of value in diagnosing invasive aspergillosis only if tests are performed at least twice weekly in high-risk patients. Antigen detection tests for invasive candidiasis are less valuable. Computed tomography scanning is particularly valuable in diagnosing invasive pulmonary fungal infection when the chest radiograph is negative or shows only minimal changes. Bronchoalveolar lavage is most useful in patients with diffuse changes on computed tomography scan. The major advances in the diagnosis of invasive fungal infection in patients with haematological malignancy or solid organ transplantation have been in the use of imaging techniques, rather than in the development of new mycological methods in the routine laboratory.

Postmortem analysis of invasive aspergillosis in a tertiary care hospital

To estimate the incidence of fatal invasive aspergillosis in a 1500-bed tertiary-care hospital and to investigate the utility of laboratory diagnostic approaches, necropsy protocols and microbiological data from 1994 and 1995 were reviewed. Among 694 necropsies from 1693 patients who died in these two years, 27 (4%) cases of invasive aspergillosis were identified. Twelve cases of invasive aspergillosis were found after transplantation of solid organs, three after bone marrow transplantation, four in patients with haematological malignancies, and five in patients with solid tumours. In 15 cases (56%) invasive aspergillosis was not suspected before death. In patients in whom serum sampling was performed seven days antemortem, the Aspergillus latex agglutination test had a sensitivity of 53% (9/17). Culture of tracheal secretions or bronchoalveolar lavage fluid from patients with pulmonary aspergillosis yielded Aspergillus fumigatus in 88% (14/16).

Comparison of an enzyme immunoassay and latex agglutination test for detection of galactomannan in the diagnosis of invasive aspergillosis

Aspergillus antigenemia was followed up in 215 consecutively observed bone marrow transplant (BMT) patients over a period of two years, using both a latex agglutination test and a sandwich immunocapture enzyme immunoassay (EIA) with a rat antigalactomannan monoclonal antibody as capture and detector antibody. For each patient, sequential sera (3 to 20) were obtained before and after BMT. No positivity was observed before BMT. After BMT, the EIA and latex agglutination test were positive in 19 and 4 patients respectively of 25 patients with confirmed aspergillosis and 14 and 7 of 15 patients with probable aspergillosis. In 19 of 25 patients with confirmed aspergillosis and 9 of 15 patients with probable aspergillosis, the EIA was more sensitive and detected infection earlier than the latex test. In all positive cases, antigenemia rapidly increased in sequential samples and remained strongly positive. In 31 of 169 (19%) BMT patients without clinical signs of aspergillosis, the EIA was occasionally positive in samples taken within the first month after BMT, giving a specificity of 81% in these patients. In non-BMT patients suffering from other diseases (n = 77), the specificity was 98.7%. The overall positive and negative predictive values for the EIA were 54% and 95% respectively. These results favour the use of EIA for early diagnosis and monitoring of aspergillosis in BMT patients, although the predictive value of transient positivity remains to be ascertained.

Comparison of antigen detection and PCR assay using bronchoalveolar lavage fluid for diagnosing invasive pulmonary aspergillosis in patients receiving treatment for hematological malignancies

The performance of a sandwich enzyme-linked immunosorbent assay (ELISA) which detects Aspergillus galactomannan (GM) was evaluated in bronchoalveolar lavage (BAL) fluid samples from 19 patients who were treated for hematological malignancies and who were suspected of having invasive pulmonary aspergillosis (IPA). All patients had fever and pulmonary infiltrates on the chest roentgenogram on the day that the BAL fluid was obtained. The ELISA results were compared with the results of culture and Aspergillus genus-specific PCR analysis of BAL fluid samples. ELISA was also performed with serum samples. Aspergillus species were detected by PCR or ELISA with BAL fluid samples from five of seven patients who had radiological evidence of IPA. Serum ELISA results were positive for all patients with ELISA-positive BAL fluid, and for four patients the serum ELISA was positive before the BAL fluid was obtained. PCR and ELISA were positive for 2 and 1 of 10 BAL fluid samples, respectively, obtained from patients without radiological evidence of IPA, and 5 and 2 of 35 BAL fluid samples, respectively, obtained from nonneutropenic patients. This preliminary investigation suggests that GM may be detected by ELISA in BAL fluid samples from patients at risk of IPA, but that monitoring of serum GM levels may allow for the earlier diagnosis of IPA. However, further evaluation in prospective studies is required.

Sandwich enzyme-linked immunosorbent assay compared with Pastorex latex agglutination test for diagnosing invasive aspergillosis in immunocompromised patients

The performance of a direct sandwich enzyme-linked immunosorbent assay (ELISA) for detecting Aspergillus galactomannan was compared with that of the Pastorex Aspergillus antigen latex agglutination (LA) test by using 532 serum samples from 61 patients at risk for invasive aspergillosis. The ELISA gave positive results earlier in the course of infection than did the LA test. A sensitivity of 70% and a specificity of 86% were obtained for the LA test and corresponding values of 90 and 84% were obtained for the ELISA when a series of serum samples was employed.