Detection of circulating galactomannan by Pastorex Aspergillus in experimental invasive aspergillosis

Rhodococcus induced false-positive galactomannan (GM), a biomarker of fungal presentation, in patients with peritoneal dialysis: case reports

BACKGROUND

Galactomannan index (GMI) at a level higher than 0.5 provides high sensitivity and specificity for the diagnosis of fungal peritonitis. Here, we report the false-positive of GMI in peritoneal dialysis (PD) effluent (PDE) due to Rhodococcus peritonitis in PD patients.

CASE PRESENTATION

GMI in PDE of case #1 and case #2 were 1.53 and 0.76, respectively, while serum GMI of both cases was less than 0.5. In addition, GMI from the specimens obtained directly from the stationary phase of Rhodococcus colonies were 1.27 and 1.56, which were isolated from case #1 and #2, accordingly.

CONCLUSION

High GMI in PDE of PD patients is not specific just for fungal infections but may also be secondary to other infections, such as Rhodococcus spp., especially in endemic areas.

Aspergillus-specific antibodies - Targets and applications

Aspergillus is a fungal genus comprising several hundred species, many of which can damage the health of plants, animals and humans by direct infection and/or due to the production of toxic secondary metabolites known as mycotoxins. Aspergillus-specific antibodies have been generated against polypeptides, polysaccharides and secondary metabolites found in the cell wall or secretions, and these can be used to detect and monitor infections or to quantify mycotoxin contamination in food and feed. However, most Aspergillus-specific antibodies are generated against heterogeneous antigen preparations and the specific target remains unknown. Target identification is important because this can help to characterize fungal morphology, confirm host penetration by opportunistic pathogens, detect specific disease-related biomarkers, identify new candidate targets for antifungal drug design, and qualify antibodies for diagnostic and therapeutic applications. In this review, we discuss how antibodies are raised against heterogeneous Aspergillus antigen preparations and how they can be characterized, focusing on strategies to identify their specific antigens and epitopes. We also discuss the therapeutic, diagnostic and biotechnological applications of Aspergillus-specific antibodies.

Rodent Models of Invasive Aspergillosis due to Aspergillus fumigatus: Still a Long Path toward Standardization

Invasive aspergillosis has been studied in laboratory by the means of plethora of distinct animal models. They were developed to address pathophysiology, therapy, diagnosis, or miscellaneous other concerns associated. However, there are great discrepancies regarding all the experimental variables of animal models, and a thorough focus on them is needed. This systematic review completed a comprehensive bibliographic analysis specifically-based on the technical features of rodent models infected with Aspergillus fumigatus. Out the 800 articles reviewed, it was shown that mice remained the preferred model (85.8% of the referenced reports), above rats (10.8%), and guinea pigs (3.8%). Three quarters of the models involved immunocompromised status, mainly by steroids (44.4%) and/or alkylating drugs (42.9%), but only 27.7% were reported to receive antibiotic prophylaxis to prevent from bacterial infection. Injection of spores (30.0%) and inhalation/deposition into respiratory airways (66.9%) were the most used routes for experimental inoculation. Overall, more than 230 distinct A. fumigatus strains were used in models. Of all the published studies, 18.4% did not mention usage of any diagnostic tool, like histopathology or mycological culture, to control correct implementation of the disease and to measure outcome. In light of these findings, a consensus discussion should be engaged to establish a minimum standardization, although this may not be consistently suitable for addressing all the specific aspects of invasive aspergillosis.

Serological Approaches

The diagnosis of invasive fungal diseases (IFD) based on clinical, radiological, and conventional microbiological findings is not reliable and is often delayed. Non-culture-based methods with higher sensitivity and specificity may reduce diagnostic time and result in decreased IFD morbidity and mortality. These methods are now increasingly used to manage patients at risk of IFD. Among available biomarkers, fungal antigens have been investigated as an aid to early diagnosis and are predominantly used as screening tests to prompt antifungal treatment mainly in patients with hematological malignancies. The revised version of the European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) consensus definitions includes some of these biological markers (galactomannan, 1,3-beta-D-glucan, cryptococcus antigen).

Fungal infections of the gastrointestinal tract in the immunocompromised host: an update

Fungal infections are one of the most significant causes of morbidity and mortality in immunocompromised patients. The incidence of invasive fungal infections, including those of the gastrointestinal tract, has increased significantly as numbers of immunocompromised patients have increased. The diagnosis of fungal infections in immunocompromised patients may be particularly problematic as these patients may present with atypical clinical features. Although Candida and Aspergillus species represent the majority of fungi diagnosed in the immunocompromised patient population, other fungi are emerging as increasingly common pathogens, and this review will focus on several important emerging fungal infections in immunocompromised patients.

False-positive Aspergillus antigenemia due to blood product conditioning fluids

The presence of Aspergillus antigens in blood transfusion components from different manufacturers was analyzed. Galacomannans were found in transfused patients, pooled platelet concentrates, fresh frozen plasma, and packed red cells collected using Fresenius Kabi bags. Galacomannans were also found in blood collection anticoagulant and platelet additive solution from this manufacturer.

Disseminated Penicillium marneffei Sepsis in a HIV-positive Thai Woman in Denmark

We report the first case of disseminated Penicillium marneffei infection, in a 32-y-old HIV positive Thai woman, in Denmark. Untreated it is a life-threatening infection. Therefore it is extremely important to consider P. marneffei in patients who are immunocompromized and who have been travelling to Southeast Asia or China.

Comparison of the value of measurement of serum galactomannan and Aspergillus-specific antibodies in the diagnosis of canine sino-nasal aspergillosis

Serology is currently used for the diagnosis of canine sino-nasal aspergillosis (SNA). However, the accuracy of serological testing using commercially available, standardized purified antigen preparations of Aspergillus (CAPurAspAg) has only been poorly documented. The aim of the present study was to assess the diagnostic value of an agar-gel double immunodiffusion (AGDD) test and an anti-Aspergillus IgG ELISA, using CAPurAspAg and the commercially available Platelia test for the detection of serum galactomannan. Sera from 17 dogs with SNA, 18 dogs with a nasal tumour (NT), 11 dogs with lymphoplasmacytic rhinitis (LPR) and 33 control dogs were tested with the 3 methods. AGDD result was positive in 76.5% of dogs with SNA, whereas all sera from dogs with non-fungal nasal disease and control dogs were negative. A positive IgG ELISA result was obtained in 88% of dogs with SNA and in 18% of dogs with LPR. All patients with NT and control dogs had a negative IgG ELISA result. The Platelia test was positive in 24% of dogs with SNA, 11% of dogs with NT, 9% of dogs with LPR and 24% of control dogs. The results of this study suggest that (1) the detection of serum Aspergillus-specific antibodies with AGDD or ELISA, using CAPurAspAg, provides excellent specificity and good sensitivity, (2) the specificity is higher for AGDD (100%) than for ELISA (96.8%) while sensitivity is higher for ELISA (88.2%) than for AGDD (76.5%) and (3) serum galactomannan quantification with the Plateliat test is unreliable for the diagnosis of canine SNA.

Fungal Infections

The incidence of invasive fungal infections has increased dramatically over the past two decades, mostly due to an increase in the number of immunocompromised patients.1–4 Patients who undergo chemotherapy for a variety of diseases, patients with organ transplants, and patients with the acquired immune deficiency syndrome have contributed most to the increase in fungal infections.5 The actual incidence of invasive fungal infections in transplant patients ranges from 15% to 25% in bone marrow transplant recipients to 5% to 42% in solid organ transplant recipients.6,7 The most frequently encountered are Aspergillus species, followed by Cryptococcus and Candida species. Fungal infections are also associated with a higher mortality than either bacterial or viral infections in these patient populations. This is because of the limited number of available therapies, dose-limiting toxicities of the antifungal drugs, fewer symptoms due to lack of inflammatory response, and the lack of sensitive tests to aid in the diagnosis of invasive fungal infections.1 A study of patients with fungal infections admitted to a university-affiliated hospital indicated that community-acquired infections are becoming a serious problem; 67% of the 140 patients had community-acquired fungal pneumonia.8

Detection of circulating galactomannan in serum samples for diagnosis of Penicillium marneffei infection and cryptococcosis among patients infected with human immunodeficiency virus

Galactomannan (GM) is a heteropolysaccharide in the cell walls of most Aspergillus and Penicillium species. Cross-reactivity of Cryptococcus neoformans galactoxylomannan in an Aspergillus GM test has also been reported. In this study, we used a Platelia Aspergillus enzyme immunoassay kit (Bio-Rad) to test serum samples obtained from 48 human immunodeficiency virus (HIV)-infected patients (15 with penicilliosis [7 with fungemia alone, 4 with cavitary lung lesions alone, 3 with both fungemia and cavitary lung lesions, and 1 with disseminated disease], 22 with cryptococcosis [11 with fungemia alone, 5 with cavitary lung lesions, 3 with both, and 3 with meningitis alone], and 11 without any invasive fungal infection [control]) for GM levels. None of the patients had aspergillosis or concurrent use of piperacillin-tazobactam or amoxicillin-clavulanate. The median time between diagnosis of fungal infection and collection of serum samples was 0 days for penicilliosis and 1.5 days for cryptococcosis. Of patients with penicilliosis, cryptococcosis, and controls, 73.3%, 13.6%, and 9%, respectively, had GM optical density (OD) indices of >0.5 (P = 0.0001). GM OD indices were higher for penicilliosis (median OD index, 4.419; range, 0.158 to >20) than for cryptococcosis (median, 0.247; range, 0.112 to 3.849) cases (P < 0.001). Patients with fungemic penicilliosis had higher OD indices (median, 10.628; range, 0.401 to >20) than patients with nonfungemic penicilliosis (median, 0.378; range, 0.158 to 4.419) and patients with cryptococcemia (median, 0.231; range, 0.112 to 1.168) (P < 0.001). Of the 15 patients with cavitary lung lesions, those with penicilliosis had higher antigen levels (median OD index, 1.641; range, 0.247 to >20) than those with cryptococcosis (median, 0.227; range, 0.112 to 3.849) (P = 0.011). This study showed that the GM OD index was significantly elevated for HIV patients with penicilliosis. The use of the GM antigen assay may facilitate earlier diagnosis of Penicillium marneffei infection for HIV-infected patients in areas of endemicity.

Advances in the serological diagnosis of invasive Aspergillus infections in patients with haematological disorders

A reliable diagnosis of invasive aspergillosis in patients with haematological malignancies is seldom achieved antemortem. Conventional laboratory diagnostic methods are insensitive and time-consuming, resulting in late diagnosis and treatment and contributing to unacceptably high mortality. As a result, routine antifungal prophylaxis and early empirical treatment have been recommended. However, overtreatment associated with these strategies results in increased toxicity and cost. The use of sensitive and rapid non-culture-based diagnostic assays, such as detection of Aspergillus antigens (galactomannan, beta-D-glucan) or detection of genomic DNA sequences may allow a shift in emphasis from empirical to pre-emptive therapy, especially when substantiated by suggestive radiological findings. These new tools may be used to confirm a presumed diagnosis of invasive aspergillosis, or, when used to screen high-risk patients, may identify an infection at the early stage of disease. The excellent negative predictive value of these assays should convince clinicians to withhold antifungal therapy in persistently febrile neutropenic patients with no other signs of fungal infection. On the other hand, consecutive positive results in a high-risk population should at least trigger a complete diagnostic work-up. This review will focus on the diagnostic utility as well as on the pitfalls of serial screening for the presence of circulating fungal antigens in haematology patients.

Galactoxylomannan does not exhibit cross-reactivity in the platelia Aspergillus enzyme immunoassay

Given the recent report of a false-positive result in the Platelia Aspergillus enzyme immunoassay in a patient with cryptococcosis and in yeast extracts and purified galactoxylomannan of Cryptococcus neoformans, we evaluated culture extracts, purified polysaccharides, clinical specimens, and specimens from animals following experimental infection. Our results revealed no cross-reactions.

High concentration of (1-->3)-beta-D-glucan in BAL fluid in patients with acute eosinophilic pneumonia

Our aim in the study was to investigate the pathogenesis of eosinophilic inflammation in patients with acute eosinophilic pneumonia (AEP), and to determine the levels of (1-->3)-beta-D-glucan, which is one of the major components of the cell wall of most fungi, in the BAL fluid (BALF) of those patients with AEP. Six patients with AEP and five patients with chronic eosinophilic pneumonia (CEP) that was in the acute stage and had been newly diagnosed, and nine healthy subjects from the Kurume University School of Medicine and the Social Institute Tagawa Hospital between 1995 and 2001 were entered into the study. In AEP patients, (1-->3)-beta-D-glucan was detected in BALF, and these findings were compared with BALF findings in patients with CEP as well as with those in healthy subjects. In the BALF of AEP patients, the mean concentration of (1-->3)-beta-D-glucan was significantly higher (p < 0.05) than that of CEP patients as well as healthy subjects. In patients with AEP, the mean concentration of (1-->3)-beta-D-glucan in BALF was significantly higher (p < 0.05) than that in the blood. In four of six patients with AEP, we measured serial changes in (1-->3)-beta-D-glucan levels, and the level of (1-->3)-beta-D-glucan in the BALF decreased with clinical improvement at follow-up. We concluded that inhaled (1-->3)-beta-D-glucan may be involved in the mechanisms of pulmonary inflammation in patients with AEP.

Antigen detection assay for identification of Penicillium marneffei infection

Two recently produced monoclonal antibodies were used to develop an antigen capture enzyme-linked immunosorbent assay (ELISA) for rapid diagnosis of Penicillium marneffei. The method was evaluated with 53 patients with culture-confirmed penicilliosis and 240 controls. The diagnostic sensitivity, specificity, and accuracy of the ELISA were 92.45, 97.5, and 96.59%, respectively.

Differences in clinical and laboratory diagnostic characteristics of penicilliosis marneffei in human immunodeficiency virus (HIV)- and non-HIV-infected patients

We compared the clinical and laboratory features of human immunodeficiency virus (HIV)- and non-HIV-infected patients with penicilliosis marneffei. HIV-infected patients had a higher incidence of fungemia. A total of 85.7% of the HIV-negative patients had underlying diseases including hematologic malignancies or had received therapy with corticosteroids or cytotoxic agents. By a Penicillium marneffei-specific mannoprotein Mp1p enzyme-linked immunosorbent assay, serum antigen titers were found to be higher in HIV-positive patients, whereas serum antibody levels were found to be higher in HIV-negative patients.

Aspergillus Fumigatus antigen detection in sera from patients at risk for invasive aspergillosis

We have developed an inhibition enzyme immunoassay (inhibition-EIA) to monitor for the occurrence of invasive aspergillosis (IA) in sera from 45 immunocompromised (IC) patients. The test uses rabbit polyclonal antibodies and a mixture of components from Aspergillus fumigatus, containing three predominant antigens with molecular weights of 18,000, 33,000, and 56,000. Circulating antigens were found in five of seven proven cases of IA due to A. fumigatus. In two of the five positive cases, antigenemia was detected with inhibition-EIA earlier than with X ray or other biological methods. No antigens were detected in the sera from two patients with proven IA due to Aspergillus flavus and Aspergillus terreus nor in the sera from four patients with probable IA. Circulating antigens were not detected in the control group, composed of 30 healthy adult blood donors. Four of the 32 at-risk patients examined, though they displayed no definite evidence of IA, gave a positive result in this test. The sensitivity, specificity, and positive predictive value of inhibition-EIA were 71.4, 94.4, and 71.2%, respectively. The data were compared with those obtained by a latex agglutination assay of galactomannan (GM) that was positive in only one patient with probable IA. The higher sensitivity obtained by inhibition-EIA may well be due to its ability to detect circulating antigens other than GM in the sera of IC patients with IA. Detecting these antigens may improve the diagnosis of IA, as they may serve as markers of this infection.

Bronchocentric granulomatosis due to Aspergillus terreus in an immunocompetent and non-asthmatic woman

This is the first report of bronchocentric granulomatosis due to Aspergillus terreus in a healthy and non-asthmatic 74-year-old Japanese woman. Following identification of the fungus, oral itraconazole therapy was begun after intrabronchial infusion of amphotericin B. No recurrence has occurred after treatment for 24 months. We should consider the possibility of bronchocentric granulomatosis including Aspergillus terreus, when an intrabronchial lesion is found even in a healthy and non-asthmatic person. Oral itraconazole after intrabronchial infusion of amphotericin B seems to be effective in such cases.

Diagnosis of Penicillium marneffei infection by quantitation of urinary antigen by using an enzyme immunoassay

Penicillium marneffei is a major cause of opportunistic infection in patients with AIDS in north and northeastern Thailand. A method for the quantitation of P. marneffei antigen in urine was developed by using fluorescein isothiocyanate-labelled purified rabbit hyperimmune immunoglobulin G in an enzyme-linked immunosorbent assay. This method was evaluated with 33 patients with culture-proven penicilliosis and 300 controls (52 healthy subjects, 248 hospitalized patients without penicilliosis) from the same area in which penicilliosis is endemic. Urinary antigen was found in all 33 (100%) patients with penicilliosis, with a median titer of 1:20,480. With undiluted samples, 67 (27%) of 248 hospital patients and 3 (6%) of 52 healthy controls were reactive. At a cutoff titer of 1:40, the urine antigen detection assay had a diagnostic sensitivity of 97% and specificity of 98% (positive predictive value, 84%; negative predictive value, 99.7%). This test offers a valuable and rapid method for the diagnosis of penicilliosis in patients with AIDS and could be a useful addition to conventional diagnostic methods in areas in which penicilliosis is endemic.

Evaluation of PCR for detection of DNA specific for Aspergillus species in sera of patients with various forms of pulmonary aspergillosis

Pulmonary aspergillosis is classified into invasive, saprophytic, and allergic forms. In this study, we evaluated the usefulness of PCR for differentiating between different forms of aspergillosis or in monitoring disease activity during treatment by detecting DNA specific for Aspergillus species in the serum. Nested PCR was used to detect Aspergillus DNA in the sera of 30 patients with various forms of pulmonary aspergillosis. The results were compared with those of latex agglutination tests for detecting galactomannan antigen. We also examined the serial changes in the results of nested PCR during and after treatment of a subgroup of patients with invasive pulmonary aspergillosis with amphotericin B. The highest proportion of positive nested PCR results were in patients with invasive aspergillosis (10 of 12; 83%), while patients with pulmonary aspergilloma had the lowest frequency of positive tests (1 of 9; 11%). These results suggested that the sensitivity of the nested PCR depends on the extent of invasion by Aspergillus species. Serial assays showed that the results of nested PCR became negative shortly after commencement of antifungal treatment and that such changes did not correlate with clinical responsiveness to treatment. Our results indicate the potential usefulness of nested PCR with serum samples for the diagnosis of invasive aspergillosis and the detection of a shift in the status of infection from a noninvasive type to invasive aspergillosis. However, the results of the nested PCR did not correlate with the response to antifungal treatment.

Detection of specific antibodies to an antigenic mannoprotein for diagnosis of Penicillium marneffei penicilliosis

The disseminated and progressive fungal disease Penicillium marneffei penicilliosis is one of the most common infectious diseases in AIDS patients in Southeast Asia. To diagnose systemic penicilliosis, we developed an enzyme-linked immunosorbent assay (ELISA)-based antibody test with Mp1p, a purified recombinant antigenic mannoprotein of P. marneffei. Evaluation of the test with guinea pig sera against P. marneffei and other pathogenic fungi indicated that this assay was specific for P. marneffei. Clinical evaluation revealed that high levels of specific antibody were detected in two immunocompetent penicilliosis patients. Furthermore, approximately 80% (14 of 17) of the documented penicilliosis patients with human immunodeficiency virus tested positive for the specific antibody. No false-positive results were found for serum samples from 90 healthy blood donors, 20 patients with typhoid fever, and 55 patients with tuberculosis, indicating a high specificity of the test. Thus, this ELISA-based test for the detection of anti-Mp1p antibody can be of significant value as a diagnostic for penicilliosis.

Outbreak of systemic aspergillosis in a neonatal intensive care unit

Small pre-term neonates are susceptible to cutaneous aspergillosis because of their immature immune system and because of the vulnerability of their skin. In addition, the common therapy with broad-spectrum antibiotic drugs and corticoids creates a favourable milieu for fungal superinfections. We present four pre-term neonates who succumbed to cutaneous aspergillosis that subsequently developed into a systemic infection. The source of the infection proved to be contaminated latex finger stalls. Three of the four patients died. The poor prognosis for systemic aspergillosis can only be improved by an early therapy with amphotericin B, possibly in liposomal form.

Usefulness of a microimmunodiffusion test for the detection of Penicillium marneffei antigenemia, antibodies, and exoantigens

Eight sera from culturally-proven cases of penicilliosis marneffei and their corresponding isolates were examined for circulating antibody(ies) and antigen, and exoantigens, respectively, using a microimmunodiffusion (MID) test. Two of the 8 sera produced strong precipitins (1-2) when reacted against control Penicillium marneffei antigen (5-week-old shaken cultures at 25 C) in the presence of control rabbit anti-P. marneffei serum. Five of the 8 sera produced a strong precipitin line when reacted against control hyperimmune serum to P. marneffei. These five sera, and one additional serum, which tested negative for antibody to P. marneffei, demonstrated the presence of antigen by reacting only against the anti-P. marneffei serum. Serological evaluations of the sera revealed that the MID test is capable of detecting antibody and antigen in AIDS patients having penicilliosis marneffei infections. Exoantigen analysis of the 8 P. marneffei isolates, which were previously identified using the conventional and time-consuming macro- and micro-morphological characteristics, showed the presence of 1 to 4 specific exoantigens in MID. With the exoantigen analysis, the identity of all of the isolates was confirmed as P. marneffei. Our studies indicated that the serological tests are useful for detecting circulating antibody and/or antigen in patients' sera, and that the exoantigen test is reliable for confirming the identity of P. marneffei cultures.

Lack of utility of the lysis-centrifugation blood culture method for detection of fungemia in immunocompromised cancer patients

We retrospectively compared the utility of a fungal isolation device (Isolator) versus conventional techniques for recovering fungal organisms from blood cultures obtained from neutropenic cancer patients. Positive cultures were deemed true pathogens, possible pathogens, or contaminants according to laboratory and clinical criteria. Fifty-three patients had 66 positive blood cultures for fungi, nine on multiple occasions. In 20 episodes true pathogens were recovered, 6 from broth medium alone, 4 from the Isolator system alone, and 10 from both systems. False-negative cultures were noted in 4 of 20 (20%) cases in which broth medium was used and in 6 of 20 (30%) cases in which the Isolator system was used. Possible pathogens were detected in 4 of 66 blood culture-positive cases. Forty-two positive cultures were considered contaminants, 1 collected from standard medium and 41 of 42 (98%) which grew only in Isolators. Eleven of 18 patients with true fungal infections expired as a result of infection, while 4 of 33 patients with a contaminant expired, none from a fungal cause. We do not advocate the routine use of Isolator tubes in the evaluation of the febrile, neutropenic patient due to the high rates of false positives and of contamination.

NMR study of the galactomannans of Trichophyton mentagrophytes and Trichophyton rubrum

Around 90% of chronic dermatophyte infections are caused by the fungi Trichophyton mentagrophytes and Trichophyton rubrum. One of the causes of the chronic infection resides in the immunosuppressive effects of the cell-wall components of these organisms. Therefore we have attempted to identify the chemical structure of galactomannan, one of the major cell-wall components. The cell-wall polysaccharides secreted by T. mentagrophytes and T. rubrum were isolated from the culture medium and fractionated into three subfractions by DEAE-Sephadex chromatography. Analysis of each subfraction by NMR indicated that there are two kinds of polysaccharides present, i.e. mannan and galactomannan. The mannan has a linear backbone consisting of alpha1,6-linked mannose units, with alpha1,2-linked mannose units as side chains. The core mannan moiety of the galactomannan was analysed by a sequential NMR assignment method after removing the galactofuranose units by acid treatment. The result indicates that the mannan moiety has a linear repeating structure of alpha1,2-linked mannotetraose units connected by an alpha1,6 linkage. The H-1 signals of the two intermediary alpha1, 2-linked mannoses of the tetraose unit showed a significant upfield shift (Deltadelta=0.05-0.08 p.p.m.), due to the steric effect of an alpha1,6-linked mannose unit. The attachment point of the galactofuranose units was determined at C-3 of the core mannan by the assignment of the downfield-shifted 13C signals of the galactomannan compared with those of the acid-modified product. In these galactomannans there were no polygalactofuranosyl chains which have been found in Penicillium charlesii and Aspergillus fumigatus.

Detection of galactomannan and complement activation in the pregnant mouse during experimental systemic aspergillosis

Foeto-placental infections are obtained when pregnant mice are challenged intravenously with conidial suspensions of Aspergillus fumigatus. This experimental model, which is used without any immuno-suppressive pretreatment, can be employed to screen for differences in foeto-placental infectivity of A. fumigatus strains when the number of colony-forming units (CFUs) in conidial suspensions used for infection is from 1 x 10(5) to 1 x 10(6). In the foeto-placental unit, hyphal growth was initiated at the periphery of the placental disc from which infection spread to the central parts of the placenta, the extrafoetal membranes and the foetus. Complement activation was noticed as a consequence of pregnancy and conidial inoculation, but was neither dose-dependent nor related to the extent of infection. Galactomannan was present in the plasma of infected mice and, in contrast to the situation in bovine placental aspergillosis, can be used as a good marker of foeto-placental aspergillosis.

Diagnostic antigenemia tests for penicilliosis marneffei

Disseminated penicilliosis marneffei is an emerging opportunistic mycosis seen in severely immunocompromised human immunodeficiency virus (HIV)-infected patients and is caused by the dimorphic fungus Penicillium marneffei. Early diagnosis and treatment improve clinical outcome. Proper diagnosis is complicated by nonspecific signs and symptoms and by difficulties in histologic recognition and species identification of the pathogen. Since no established immunodiagnostic methods for penicilliosis marneffei are available, we attempted to develop separate immunodiffusion tests to detect P. marneffei antigens and antibodies in patient serum specimens and a latex agglutination test for antigenemia. Antigens consisted of 2-week-old fission arthroconidial filtrates produced in Pine's broth at 37 degrees C. Rabbit antisera were prepared against the 10 x -concentrated filtrate antigens. Studies were carried out with 17 serum specimens from HIV-seropositive adult Thai patients with penicilliosis marneffei and 15 control serum specimens from Thai persons free of HIV and P. marneffei infection. The immunodiffusion tests detected P.marneffei antigenemia in 10 (58.8%) of 17 patients, whereas the latex agglutination test detected antigenemia in 13 (76.5%) of the 17 patients. Antibody was demonstrated in only 2 of the 17 patient sera. All of the tests appeared to be highly specific, since none were positive with sera from 15 Thai control patients, six serum samples containing cryptococcal antigen, or six urine specimens positive for Histoplasma polysaccharide antigens.

Plasma (1-->3)-beta-D-glucan and fungal antigenemia in patients with candidemia, aspergillosis, and cryptococcosis

(1-->3)-beta-D-Glucan is one of the major structural components of fungi, and it seems that it can be detected by the fractionated (1-->3)-beta-D-glucan-sensitive component from a Limulus lysate, factor G. We evaluated the concentration of (1-->3)-beta-D-glucan by using factor G and other fungal antigens in 24 patients with clinical evidence of mycosis and 36 healthy subjects. The mean concentration of (1-->3)-beta-D-glucan in the plasma of the healthy subjects was found to be 2.7 +/- 1.9 pg/ml (range, < 6.9 pg/ml), and it was found to be substantially higher in all 11 patients with candidemia (mean, 2,207.4 pg/ml; range, 325.4 to 8,449.0 pg/ml). Eight of those 11 patients with candidemia (73%) were positive for the Cand-Tec heat-labile candida antigen and only 3 patients (27%) were positive for mannan antigen. Three patients with invasive pulmonary aspergillosis were positive for galactomannan and had, in addition, high concentrations of (1-->3)-beta-D-glucan (mean, 323.3 pg/ml; range, 27.0 to 894.0 pg/ml). All 10 patients with cryptococcosis (including 2 patients with probable cryptococcosis) were positive for cryptococcal antigen by the Eiken latex test; however, (1-->3)-beta-D-glucan levels were not elevated in these patients (mean, 7.0 pg/ml; range, < 16.5 pg/ml). Our results indicated that (1-->3)-beta-D-glucan levels are elevated in patients with candidiasis and aspergillosis but not in those with cryptococcosis.

Invasive aspergilloma of the frontal base causing internal carotid artery occlusion

BACKGROUND

Aspergilloma of the nasal cavity or paranasal sinuses rarely extends through the skull base into the intracranial space.

PATIENT

The patient was a 79-year-old man in a nonimmunosuppressive state who had an invasive aspergilloma of the base of the frontal lobe.

CLINICAL COURSE

The patient, whose initial symptom was a visual disturbance, eventually developed an occlusion of the right internal carotid artery and died. The diagnosis was established by a transsphenoidal biopsy.

CONCLUSIONS

A rare case of invasive aspergilloma of the frontal base is described with emphasis on the findings of low-intensity mass on the T2-weighted magnetic resonance imaging (MRI). The prognosis in this disease is very poor. Early diagnosis and surgical treatment, combined with postoperative antifungal drug therapy, would have improved the outcome.

Development of specific fluorescent-antibody test for tissue form of Penicillium marneffei

The diagnosis of penicilliosis marneffei can be difficult because the clinical manifestations mimic those of tuberculosis, histoplasmosis, and other mycotic infections. Furthermore, the tissue form of Penicillium marneffei can be confused with those of Histoplasma capsulatum and Cryptococcus neoformans. To facilitate the rapid detection and identification of P. marneffei in clinical materials, we sought to develop a specific indirect fluorescent-antibody (IFA) reagent for this dimorphic pathogen. Preliminary IFA studies with yeast-like cells (fission arthroconidia) of P. marneffei indicated that these cellular elements stained with antiglobulins against culture filtrate antigens and whole yeast-like cellular antigens. Both types of antiglobulins reacted with the yeast-like cells of P. marneffei and with H. capsulatum, but not with their respective mycelial forms. The antiglobulins also failed to react with the yeast and hyphal forms of a variety of other heterologous fungi. Specific antiglobulins useful in an IFA test for identifying P. marneffei yeast-like cells in culture or in clinical materials were produced by adsorptions with yeast-form cells of H. capsulatum. The yeast-like culture filtrate antigens of P. marneffei are preferred for use in the production of the specific antiglobulins because they stained P. marneffei yeast-like elements more intensely than antiglobulins produced against intact yeast-like cells.

Highly sensitive detection of fungal antigens by ultrasound-enhanced latex agglutination

Treatment with ultrasound has been employed to greatly enhance the sensitivity of commercially available latex agglutination tests for fungal antigens. This 5 min procedure detects 40 pg ml-1 of Candida albicans mannan and 70 pg ml-1 of Aspergillus fumigatus galactomannan, a 250 and 500-fold improvement respectively over conventional agglutination test sensitivities. The ultrasound-enhanced test offers the possibility of improved diagnosis and management of patients with systemical candidosis or invasive aspergillosis.

Detection of (1-3)-beta-D-glucan in a rat model of aspergillosis

The G test containing factor G, fractioned from the Limulus lysate, was used to detect (1-3)-beta-D-glucan in a rat model of aspergillosis. Aspergillus fumigatus strain MF-13, 1 x 10(4) conidia, were inoculated transtracheally into rats treated with cortisone acetate (100 mg/kg) and fed a low-protein (8%) diet. Increased serum (1-3)-beta-D-glucan was found on the sixth day after inoculation in concentrations of 370 +/- 178 pg/ml (mean +/- SD) in untreated controls, and 154 +/- 43 pg/ml in rats treated with 0.5 mg/kg of amphotericin B. On day 11 (1-3)-beta-D-glucan concentrations were 2,590 +/- 2,940 pg/ml and 448 +/- 442 pg/ml, respectively. The elevation in levels of (1-3)-beta-D-glucan increased in correlation with the elevation of galactomannan antigen titers; (1-3)-beta-D-glucan is thus measurable during experimental aspergillosis in rats.

Value of antigen and antibody detection in the serological diagnosis of invasive aspergillosis in patients with hematological malignancies

In a study to determine the value of antigen and antibody detection in the serological diagnosis of invasive aspergillosis in patients with hematological malignancies, 436 sequential serum samples from 79 neutropenic patients were tested. Circulating galactomannan antigen was detected with a latex agglutination method (Pastorex Aspergillus) and antibody to Aspergillus fumigatus with an immunodiffusion test on agar gel. Among the 79 patients 18 cases of invasive aspergillosis were detected (4 proven, 6 highly probable, 3 probable, 5 suspected). Antigen was detected in 7 of these 18 patients. The sensitivity of the antigen test was 38.8% and the specificity 95%. The antibody test showed 55.5% sensitivity and 100% specificity. In this study the antigen test was less sensitive than previously reported but highly specific and might serve as a supplementary diagnostic test.

Retrospective evaluation of a latex agglutination test for diagnosis of invasive aspergillosis in immunocompromised patients

A commercial latex agglutination (LA) test for the detection of circulating Aspergillus galactomannan was evaluated in sera obtained from 121 immunocompromised patients, including 19 with proven invasive pulmonary aspergillosis. Patient urine (the specimen of choice for detection of galactomannan) was not tested with the LA test as 34 of 81 specimens from controls gave false-positive results. The sensitivity (95%), specificity (90%) and negative predictive value (99%) of the LA test were similar to previously published results obtained with two EIAs. However, the positive predictive value was only 67% compared to > or = 95% obtained with the EIAs. In addition, the LA test was also of less value than the EIAs in predicting the onset of invasive pulmonary aspergillosis. It was the earliest indicator of infection in only 1 of 19 proven cases.

Specific detection of Aspergillus and Penicillium species from respiratory specimens by polymerase chain reaction (PCR)

A polymerase chain reaction (PCR) method capable of detecting both Aspergillus fumigatus infections, pulmonary non-fumigatus Aspergillus species (spp.) and Penicillium spp. from clinical specimens was established. The primer pair was designed on the basis of the sequence of the 18S-ribosomal RNA gene of A. fumigatus and P. notatum. A 385 bp product was successfully amplified by this PCR method from all of 12 medically important Aspergillus spp. and Penicillium spp. (38 strains), but not from human, calf, Escherichia coli, methicillin-resistant Staphylococcus aureus (MRSA), any of 14 medically important yeastlike fungal species tested (32 strains) including Candida albicans, several non-albicans Candida and Saccharomyces cerevisiae, Cryptococcus neoformans, Mucor spp. or Pneumocystis carinii. This specificity was subsequently confirmed by Southern hybridization analysis. The established PCR can detect such a small amount as 1 pg of A. fumigatus DNA by staining the PCR product with ethidium bromide. With sputum specimens from clinically diagnosed aspergilloma patients, this PCR technique was demonstrated to be a more sensitive diagnostic method for Aspergillus infections than conventional culture techniques.

Variability of Aspergillus nidulans antigens with media and time and temperature of growth

The influence of culture medium and time and temperature of growth on the appearance of Aspergillus nidulans antigens was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, followed by silver staining or Western blot (immunoblot), of the proteins present in total cellular extracts or culture supernatants. Samples in the exponential, deceleration, and stationary growth phases were selected by biochemical, morphological, and ultrastructural criteria. Protein and antigen patterns (detected with rabbit antibodies) from total extracts were very similar in all cases, and the major differences observed seemed to depend on the age of the cultures. Culture supernatant patterns were highly dependent on the type of medium (complex or defined) and the age of the culture. Temperature did not significantly influence these results. The reproducible reactivity of selected human sera from aspergilloma-affected individuals was strictly associated with the use of defined media, especially Czapek Dox-AOAC, in both total extracts and culture supernatants. Extended growth times were necessary in the case of metabolic antigens (those obtained from culture supernatants). Screening of a battery of 10 selected human serum samples from patients with aspergilloma or invasive aspergillosis demonstrated that two of the antigens (96 to 98 and 45 kDa) from stationary-phase culture supernatants in Czapek Dox-AOAC medium were consistently reactive. When considered together as one unit, both antigens reacted with more than 50% of the sera, and at least one or the other of the antigens reacted with more than 90% of the sera. Less consistent results were obtained for two somatic antigens (from total cell extracts) of 45 to 50 and 20 to 22 kDa.

Experimental aspergillosis in guinea pigs: influence of itraconazole on fungaemia and invasive fungal growth

The guinea pig model of experimental aspergillosis was used to evaluate the efficacy of itraconazole 2.5 and 5 mg kg-1 in preventing the invasive phase of the disease when animals were already loaded with Aspergillus conidia. Evaluations were made by recording the survival rates, culturing fragments of nine organs, examining seven organs by means of histochemistry and immunohistochemistry (mAb EB-A1 to Aspergillus galactomannan) and by serological titration of galactomannan. The data indicate that itraconazole is highly effective in preventing true invasive aspergillosis. Serological evaluations of antigenaemia suggest that low titres may only reflect fungaemia, while titres of 1:8 and above are suggestive of invasive disease.

Monoclonal antibodies against a 97-kilodalton antigen from Aspergillus flavus

We prepared a panel of five monoclonal antibodies (MAbs) directed against Aspergillus flavus that all reacted against one 97-kDa antigen by western blot (immunoblot). Flow cytometry demonstrated that these antibodies bound (in increasing degrees) to all morphologic stages of A. flavus growth: conidia, swollen conidia, and hyphae. Cross-reactivity among species was examined by enzyme-linked immunosorbent assay of fungal culture filtrates. Four MAbs reacted with 10 of 11 A. flavus isolates, and the fifth one reacted with 9 of them. One MAb also reacted with A. fumigatus, two reacted with A. niger, A. wentii, and A. nidulans, and all five reacted with A. ochraceus. None reacted with A. terreus, A. glaucus, A. versicolor, or a Penicillium species. Each MAb bound to A. flavus hyphae in formalin-fixed paraffin sections of a muscle biopsy from a confirmed human case of invasive aspergillosis. In summary, these MAbs identified a 97-kDa antigen found on A. flavus that is both surface bound and an exoantigen. Either the same or a cross-reacting antigen is present in A. fumigatus and other Aspergillus species.

Fungal polysaccharides

Fungal polysaccharides are cell wall components which may act as antigens or as structural substrates. As antigens, the role of mannans in Saccharomyces cerevisiae and Candida albicans, and of glycoproteins in Aspergillus fumigatus are discussed. Analyses on beta-glucan synthetase in Paracoccidioides brasiliensis and the inhibitory effect of Hansenula mrakii killer toxin on beta-glucan biosynthesis are also considered.

New cause for false-positive results with the Pastorex Aspergillus antigen latex agglutination test

The Pastorex Aspergillus antigen test for detection of Aspergillus galactomannan antigen in the sera of patients with invasive aspergillosis is used in many clinical laboratories. A serum sample contaminated with Penicillium chrysogenum gave a strongly positive reaction (1:128) which was heat stable, was not eliminated by pronase treatment, and was not detected by a normal rabbit globulin control. This observation was shown to be due to cross-reactions of the monoclonal antibody EB-A2 used by the kit with several airborne fungi likely to contaminate serum samples, including Penicillium chrysogenum, Cladosporium herbarum, Acremonium species, Alternaria alternata, Fusarium oxysporum, Wangiella dermatitidis, and Rhodotorula rubra.

Detection of galactomannan and the 18 kDa antigen from Aspergillus fumigatus in serum and urine from cattle with systemic aspergillosis

Serum and urine samples from cattle with experimental and spontaneous systemic mycotic infections were tested for the presence of galactomannan and the 18 kDa antigen from Aspergillus fumigatus by an inhibition ELISA and immunoblotting, respectively. High levels of galactomannan (approximately 80 ng/ml.) were detected in serum from two of three calves experimentally infected with A. fumigatus. In two out of three cows with spontaneous acquired aspergillosis a similar amount of galactomannan was detected. Galactomannan was not found in serum samples of 20 cows which aborted due to either experimental or spontaneous placental aspergillosis. Twenty-four of forty urine samples from normal cattle reacted positively in the ELISA, consequently, the assay was not applicable on bovine urine. The 18 kDa antigen from A. fumigatus was detected in the urine from one calf out of three calves experimentally infected with aspergillosis and in the urine from one cow with spontaneous aspergillosis. It is concluded that detection of galactomannan in serum and the 18 kDa antigen in urine may be used as an aid for the diagnosis of disseminated bovine aspergillosis with the exception of placental and probably gastrointestinal localization.

Experimental systemic bovine zygomycosis with reference to pathology and secretion of antigen into urine

ELISA and immunoblotting were applied for the characterization of somatic antigens from Absidia corymbifera. Immunoblotting revealed major antigenic bands at 11 to 81 kDa. The ELISA showed some crossreactivity towards somatic antigens from other fungi. However, the crossreactivity was especially observed with somatic antigens from other fungi of the zygomycetes. The ELISA and immunoblotting assays were applied to urine samples from two groups of 3 calves each systemically infected with A. corymbifera and Aspergillus fumigatus, respectively. The immunoreactivity of the urine samples was similar by the two assays. Somatic antigens were demonstrated in the urine of all three calves infected with A.corymbifera, whereas only one of the calves with systemic aspergillosis was antigen positive. The level of antigen in the positive urine samples varied from 50 to 210 ng/ml.