Applicability of the Platelia EIA® Aspergillus test for the diagnosis of aspergilosis in penguins.

A L Cabana,M C A Meireles,M O Xavier,J F Mendes,A M Martins,R P Silva-Filho,A J Teles

doi:10.1590/1519-6984.171140

A L Cabana, M C A Meireles + Show 5 more

Open Access

https://doi.org/10.1590/1519-6984.171140

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Abstract

Even today, an effective diagnostic test for aspergillosis in penguins is unknown, being the gold standard post-mortem examinations. The fungal antigen galactomannan (GM) has been used as a biomarker of disease in humans and is detected by the Platelia Aspergillus EIA (BioRad)®, a commercial kit based on the sandwich ELISA technique. It is standardized for use in neutropenic patients, however studies have demonstrated its usefulness also possible for birds. The aim of our study was to evaluate the effectiveness of Platelia Aspergillus EIA® test (BioRad-US) in the diagnosis of aspergillosis in Magellanic penguins, determining sensitivity, specificity, and positive and negative predictive values for different cut-off points. Were included in the study, blood serum samples (n = 29) Magellanic penguins in captivity that died by aspergillosis. Detection of GM was performed following manufacturer's instructions and the GM index was obtained by dividing the average value of OD of the duplicate of the clinical sample by duplicate OD of the average value of the cut-off sample provided by the kit. Through information database results were obtained for the presence of anti-Aspergillus fumigatus antibodies detected by agar gel immunodiffusion (AGID) for all serum samples. Results were analyzed using chi-square test and Kruskal-Wallis from SPSS 20.0, IBM®. ROC curve was obtained and from this, rates of sensitivity, specificity, positive and negative predictive values were also calculated based on four different cutoff points (0.5, 1.0, 1.5 and 2.0). The serum GM index did not differ between animals of the case and control group (pkw =0.097). In determining the ROC curve for serum GM detection the value of area under the curve was 0.635. From the values determined by the coordinate of the curve, four different cut points (0.5, 1.0, 1.5 and 2.0) were analyzed, resulting in sensitivity rates ranging from 86.2 to 34.5% % and specificity between 87% and 26.1%. By comparing the serum GM index in group case as the presence or absence of antibodies detected by AGID was found p=0.503. The detection of GM the Platelia Aspergillus EIA® test seems is not be useful for the diagnosis of aspergillosis in naturally infected penguins.

Highlights

Due to the high incidence of aspergillosis in penguins determining high mortality rates in these animals in captivity as well as the difficulty of the definitive diagnosis of ante-mortem disease in this species, this study aim to evaluate the effective of Platelia Aspergillus EIA test (Bio-Rad-US) the diagnosis of aspergillosis in naturally infected Magellanic penguins, determining sensitivity, specificity, and positive and negative predictive values for different cutoff points
This study evaluated for the first time the applicability of the commercial Aspergillus EIA Platelia kit for the diagnosis of aspergillosis in Magellanic penguins naturally infected, finding no significant difference in GM ratios
A single study the this population with a similar was described by Cray et al (2009b), the authors included 56 birds with aspergillosis, of which only three were penguins, it is not possible to extrapolate the test efficacy results obtained by the authors for Sphenisciformes family

Summary

Introduction

Aspergillus species have been known for decades as important pathogens of birds, leading to high mortality rates, including the Spheniscidae family, being about 90-95% of the cases of aspergillosis caused by Aspergillus section Fumigati (Cray et al, 2009b; Cabana, 2013; Xavier et al, 2011).The diagnosis ante-mortem of invasive aspergillosis (IA) in birds is limited and traditional techniques, such as blood tests, biochemical tests and imaging studies may reveal only nonspecific changes (Xavier et al, 2011; 2008; 2007).Mycological classic tests have low sensitivity and / or specificity, and use of serological tests, indicated in the literature (Cabana et al, 2015; Tell, 2005) it is not in routine use, as the gold standard is still restricted to histopathological and mycological post-mortem (Cray et al, 2009a, b).Modern techniques for the diagnosis of aspergillosis by direct detection of antigen galactomannan (GM) in clinical samples have been increasingly used for the diagnosis of IA in humans from different species. The GM is a polysaccharide present in the fungal cell wall of the genus Aspergillus, a family of derivatives galactofuranose antigens Their release into the bloodstream occurs during the growth of hyphae in tissue invasion process (Mennink-Kersten et al, 2004; Nucci and Colombo, 2012). This molecule can be considered as an important biomarker for the determination of invasive fungal infections by Aspergillus spp. in different clinical samples to be water soluble (Maertens et al, 2007; Xavier et al, 2011)

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