Katrien Lagrou

Optimization of the Cutoff Value for the Aspergillus Double-Sandwich Enzyme Immunoassay

BACKGROUND Many health care centers worldwide use the Platelia Aspergillus enzyme immunoassay (PA-EIA; Bio-Rad Laboratories) for diagnosis of invasive aspergillosis (IA). A cutoff optical density (OD) index of 1.5 was originally recommended by the manufacturer, but in practice, most institutions use lower cutoff values. Moreover, a cutoff OD index of 0.5 was recently approved in the United States. In the present study, we set out to optimize the cutoff level by performing a retrospective analysis of PA-EIA values for samples that had been obtained prospectively from adult patients at risk for IA at 2 European health care centers. METHODS In total, 239 treatment episodes were included of which there were 19 episodes of proven IA and 19 episodes of probable IA. Per-episode and per-test analyses and receiver operating characteristic curves were used to determine the optimal cutoff value. RESULTS In the per-episode analysis, lowering the cutoff OD index for positivity from 1.5 to 0.5 increased the overall sensitivity by 21% (from 76.3% to 97.4%) but decreased the overall specificity by 7% (from 97.5% to 90.5%). Requiring 2 consecutive samples with an OD index > or = 0.5 resulted in the highest test accuracy, with an improved positive predictive value. At a cutoff OD index of 0.5, the antigen test result was positive during the week before conventional diagnosis in 65% of cases and during the week of diagnosis in 79.5% of cases. CONCLUSIONS A cutoff OD index of 0.5--identical to the approved cutoff in the United States--improves the overall performance of the PA-EIA for adult hematology patients.

ECIL guidelines for the diagnosis of Pneumocystis jirovecii pneumonia in patients with haematological malignancies and stem cell transplant recipients

The Fifth European Conference on Infections in Leukaemia (ECIL-5) convened a meeting to establish evidence-based recommendations for using tests to diagnose Pneumocystis jirovecii pneumonia (PCP) in adult patients with haematological malignancies. Immunofluorescence assays are recommended as the most sensitive microscopic method (recommendation A-II: ). Real-time PCR is recommended for the routine diagnosis of PCP ( A-II: ). Bronchoalveolar lavage (BAL) fluid is recommended as the best specimen as it yields good negative predictive value ( A-II: ). Non-invasive specimens can be suitable alternatives ( B-II: ), acknowledging that PCP cannot be ruled out in case of a negative PCR result ( A-II: ). Detecting β-d-glucan in serum can contribute to the diagnosis but not the follow-up of PCP ( A-II: ). A negative serum β-d-glucan result can exclude PCP in a patient at risk ( A-II: ), whereas a positive test result may indicate other fungal infections. Genotyping using multilocus sequence markers can be used to investigate suspected outbreaks ( A-II: ). The routine detection of dihydropteroate synthase mutations in cases of treatment failure is not recommended ( B-II: ) since these mutations do not affect response to high-dose co-trimoxazole. The clinical utility of these diagnostic tests for the early management of PCP should be further assessed in prospective, randomized interventional studies.

A unifying hypothesis and a single name for a complex globally emerging infection: hantavirus disease.

In the January 2011 issue of this journal, Swedish authors described three severe cases of predominantly pulmonary infection with the European hantavirus Puumala virus (PUUV), leading to death due to refractory shock in two of these patients [1]. Of note, the kidneys in these two fatal cases had, on autopsy, no prominent inflammatory infiltrates or haemorrhages, in contrast with the lungs which showed extensive interstitial oedema and mononuclear cell infiltrates, mainly CD8 T lymphocytes. As the authors justly point out, even in the title of their communication, it is now, perhaps, time to revise the sacro-saint paradigm existing since 1994 of two “different” infectious diseases caused by the same genus of rodent-borne hantaviruses of the Old and the New World, respectively. The former would target mainly the human kidney, and the latter mainly the human lung, resulting in the so-called “haemorrhagic fever with renal syndrome” (HFRS) [2] or the “hantavirus pulmonary syndrome” (HPS) [3]. When it appeared that the failing heart was, in fact, the most direct cause of death in refractory shock in HPS, yet another name, “hantavirus cardio-pulmonary syndrome” (HCPS), was added to the already bewildering list of over 60 mostly exotic synonyms for a disease described already in 1913 by Russian doctors in Vladivostok. On the other side of the Eurasian landmass and in 1934, Swedish doctors described an epidemic renal affection which they called “nephropathia epidemica” (NE), which was proven in 1979 to be, in fact, a milder variant of HFRS, caused by PUUV [4]. To date, 23 distinct species of hantaviruses have been recognized, each carried by their more or less specific rodent or insectivore reservoir. The most important pathogens are Hantaan (HTNV) and Seoul virus (SEOV) in the Far-East (where >90% of worldwide hantavirus infections occur), PUUV and Dobrava-Belgrade virus (DOBV) in Europe and Russia, and Sin Nombre (SNV) and Andes virus (ANDV) in the Americas [5]. The first HPS report that appeared in 1994 [3] described “a newly recognized disease” which was of paramount importance for a better understanding of an emerging viral infection in the New World, and generated an explosive surge in hantavirus research. However, H(C)PS was, and remains, a rare disease, with only 560 confirmed cases in the USA during the 1993–2010 period [6] (meaning 30 cases/year) and about 2,500 cases in the entire Americas, albeit with a much higher case fatality rate (CFR) of 35% [7]. This is in stark contrast with the current 0.1–0.2% CFR for PUUV infections with high morbidity in the Old World, with now over 50,000 registered NE cases in Europe, and even over 175,000 in Western Russia. In some peak years, Russia witnessed more than 10,000 cases/year (e.g. 11,413 in 1985), whereas registered NE numbers in Western Europe recently took epidemic proportions (e.g. 3,259 in Finland, 2008, and 1,874 in Germany, 2010), probably as a result of global warming [8]. Thus, it should not come as a surprise that Russian or European clinicians had or have now identified clinical characteristics claimed as being specific for “American HPS”. The Centers for Disease J. Clement (*) : P. Maes :K. Lagrou :M. Van Ranst National Reference Laboratory for Hantavirus Infections, University Hospital Gasthuisberg, Herestraat 49, 3000 Leuven, Belgium e-mail: jan.clement@uzleuven.be

Zoonotic transmission of Cryptococcus neoformans from a magpie to an immunocompetent patient

Abstract.  Lagrou K, Van Eldere J, Keuleers S, Hagen F, Merckx R, Verhaegen J, Peetermans WE, Boekhout T (University Hospital Leuven, Leuven, Belgium; and Centraalbureau voor Schimmelcultures, CT Utrecht, the Netherlands) Zoonotic transmission of Cryptococcus neoformans from a magpie to an immunocompetent patient (Case report). J Intern Med 2005; 257: 385–388.

Clinical Predictive Value of Real-Time PCR Quantification of Human Cytomegalovirus DNA in Amniotic Fluid Samples

The aim of this study was to evaluate the diagnostic reliability and prognostic significance of the quantification of cytomegalovirus (CMV) DNA in amniotic fluid (AF). We retrospectively reviewed the results for 282 amniotic fluid samples that had been tested for CMV by a quantitative real-time PCR. We observed three cases in which no CMV genomes were detected in the AF but in which the children were nevertheless congenitally infected. Hence, we conclude that a negative result by PCR for CMV in AF cannot rule out the possibility of congenital infection. No false-positive PCR results were observed. A correlation between the CMV viral load in AF and the fetal and neonatal outcomes could not be demonstrated in our study. Instead, a correlation was found between the CMV viral load and the gestational age at the time of amniocentesis.

Evaluation of the New Architect Cytomegalovirus Immunoglobulin M (IgM), IgG, and IgG Avidity Assays

ABSTRACT A panel of new cytomegalovirus (CMV) assays for use on the Architect instrument has been developed, including a CMV avidity assay based on a new technology. The purpose of this study was to compare the performance characteristics of the fully automated CMV immunoglobulin M (IgM), IgG, and IgG avidity tests on the Architect instrument with those of other available assays. A total of 503 consecutive fresh patient serum specimens (routine serum specimens) and 96 serum specimens from 33 pregnant women with a recent CMV primary infection (seroconversion serum specimens) were tested for CMV IgM and IgG by the Architect (Abbott), Vidas (BioMérieux), and Enzygnost (Siemens) assays. The seroconversion sera and 100 preselected serum specimens IgM negative and IgG positive by the AxSYM assay were also tested by the IgG avidity tests on the Architect and Vidas instruments. The relative agreements for CMV IgM determination with routine sera between the Architect assay and the Vidas, Enzygnost, and AxSYM assays were 97%, 94%, and 93%, respectively, for the CMV IgM tests and 99%, 98%, and 98%, respectively, for the CMV IgG tests. The specificities of the CMV IgG avidity test were 98% for the Architect assay and 76% for the Vidas assay. No high CMV IgG avidity test results were found within the first 3 months after seroconversion by either of those assays. The correlation between the results of the newly developed CMV IgM and IgG tests on the Architect instrument with the Vidas and Enzygnost assays was excellent (≥94%). The CMV IgG avidity test reliably excluded patients with recent infections and showed an excellent specificity (98%).

Nationwide Surveillance of Azole Resistance in Aspergillus Diseases

ABSTRACT Aspergillus disease affects a broad patient population, from patients with asthma to immunocompromised patients. Azole resistance has been increasingly reported in both clinical and environmental Aspergillus strains. The prevalence and clinical impact of azole resistance in different patient populations are currently unclear. This 1-year prospective multicenter cohort study aimed to provide detailed epidemiological data on Aspergillus resistance among patients with Aspergillus disease in Belgium. Isolates were prospectively collected in 18 hospitals (April 2011 to April 2012) for susceptibility testing. Clinical and treatment data were collected with a questionnaire. The outcome was evaluated to 1 year after a patients inclusion. A total of 220 Aspergillus isolates from 182 patients were included. The underlying conditions included invasive aspergillosis (n = 122 patients), allergic bronchopulmonary aspergillosis (APBA) (n = 39 patients), chronic pulmonary aspergillosis (n = 10 patients), Aspergillus bronchitis (n = 7 patients), and aspergilloma (n = 5 patients). The overall azole resistance prevalence was 5.5% (95% confidence interval [CI] 2.8 to 10.2%) and was 7.0% (4/57; 95% CI, 2.3 to 17.2%) in patients with APBA, bronchitis, aspergilloma, or chronic aspergillosis and 4.6% in patients with invasive aspergillosis (5/108; 95% CI, 1.7 to 10.7%). The 6-week survival in invasive aspergillosis was 52.5%, while susceptibility testing revealed azole resistance in only 2/58 of the deceased patients. The clinical impact of Aspergillus fumigatus resistance was limited in our patient population with Aspergillus diseases.

Burden of serious fungal infections in Belgium

We aimed to estimate the total number of serious fungal infections occurring yearly in Belgium. The number of cryptococcal infections was retrieved from the National Reference Center for Mycosis. Populations at risk and fungal infections frequencies in these populations were used to estimate incidence or prevalence of other fungal infections. The Belgian population consists of 11.10 million people. Cryptococcal meningitis is rare. In all, 15 of the 1227 newly diagnosed HIV/AIDS cases presented with Pneumocystis jirovecii pneumonia. This accounts for ±14% of total PCP cases (n = 120). The incidence of candidaemia is estimated as 5/100 000 resulting in 555 cases and 213 deaths. A total number of 675 invasive aspergillosis cases and ≥169 deaths attributed to this infection were calculated. Chronic pulmonary aspergillosis is estimated to be prevalent in 662 cases. Allergic bronchopulmonary aspergillosis cases were estimated to be 23 119 applying a 2.5% and 15% rate in adult asthma and cystic fibrosis patients respectively. Severe asthma with fungal sensitisation cases was estimated to be 30 402. There were 174 760 women with recurrent Candida vaginitis assuming a 6% rate in women aged between 15 and 50. Approximately 233 000 people of the Belgian population (2.1%) are estimated to suffer from a fungal infection on a yearly basis.

Increasing candidemia incidence from 2004 to 2015 with a shift in epidemiology in patients pre-exposed to antifungals

Candidaemia is an important health problem in immunocompromised patients with an epidemiology varying with region, period and patient population involved. The occurrence of candidaemia and the associated species distribution over a 12‐year period at a large tertiary care centre in Belgium were analysed. The trend in incidence in the intensive care units (ICUs) and non‐ICUs was investigated as well as the influence of antifungal exposure on the species distribution. From 2004 until 2015, 865 candidaemia episodes occurred in 826 patients at the University Hospitals Leuven. Candida albicans (59%) remained the most important cause of candidaemia, followed by C. glabrata (22.4%) and C. parapsilosis (8%). The mean incidence in the whole hospital was 1.48 per 10 000 patient days (PD). The incidence in ICUs increased reaching up to 10.7 per 10 000 PD whereas in the non‐ICUs, the incidence decreased. Prior exposure to fluconazole and echinocandins was associated with candidaemia caused by less susceptible species. Candidaemia incidence increased in the whole hospital, driven by ICUs. Surveillance of candidaemia epidemiology on a local scale is of high value to guide empirical treatment strategies.

Letter to the Editor: Leptospirosis versus hantavirus infections in the Netherlands and in Belgium, 2000 to 2014

J Clement (jan.clement@uzleuven.be)1, M Van Esbroeck2, K Lagrou3, J Verschueren2, N P Sunil-Chandra4, M Van Ranst1 1. National Reference Centre for Hantaviruses, Clinical and Epidemiological Virology, University Hospitals of Leuven, Leuven, Belgium 2. National Reference Laboratory for Leptospirosis, Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium 3. Department of Microbiology & Immunology, Catholic University Leuven, and Clinical Department of Laboratory Medicine, University Hospitals of Leuven, Leuven, Belgium 4. Department of Medical Microbiology, Faculty of Medicine, University of Kelaniya, Sri-Lanka