Galactomannan

M. Hoenigl

Author address: 

Medizinische Universitaet Graz, Graz, Austria

Abstract: 

Galactomannan (GM) is a polysaccharide component of the cell wall of Aspergillus spp. that is released into bloodstream by growing hyphae and germinating spores/conidia. In patients with invasive aspergillosis GM is measurable in peripheral blood (serum and plasma), bronchoalveolar lavage fluid (BALF), urine, cerebral spinal fluid, or pleural fluid (1-3). The test, however, has important limitations in the presence of antimould prophylaxis and empirical treatment, where sensitivity of GM decreases significantly (4-5). Sensitivity of GM may be decreased in particular in serum samples also when reducing the cutoff of 0.5 ODI, which is currently recommended in revised EORTC/MSG criteria. Studies have shown that although the performance of diagnostic tests for invasive aspergillosis are superior in BALF compared to blood (6), the sensitivities of all diagnostic tests are substantially reduced in the presence of mold-active antifungal prophylactic or empirical treatment also in BALF. Reinwald et al. prospectively evaluated GM levels in BAL samples from 29 patients being treated for probable or proven IA and found a GM cut-off of 0.5 ODI to be more sensitive (79%) but equally specific (96%) to a 1.0 ODI cut-off (7). Subsequently, Eigl and colleagues showed that a GM cut-off in BAL samples of 0.5 ODI provided 71% sensitivity in patients receiving mold-active antifungal therapy at the time of sampling compared to 95% in untreated patients (4). A 1.0 ODI cut-off gave sensitivities of 52% and 81%, respectively (4). Thus, in patients receiving mold-active antifungal agents, a 0.5 ODI cut-off for BAL GM seems reasonable—but sensitivity is still impaired compared to untreated individuals. Importantly, the sensitivity of BAL GM is likely to have been overestimated in those studies since GM was used as a mycological criterion for defining probable IPA, which represented the majority of cases in those studies. References: (1) Reischies FM, Raggam RB, Prattes J et al. Urine galactomannancreatinine ratio for detection of invasive aspergillosis in patients with hematologic malignancies. J Clin Microbiol. 2016; 54: 771-774. (2) Prattes J, Flick H, Pruller F et al. Novel tests for diagnosis of invasive aspergillosis in patients with underlying respiratory diseases. Am J Respir Crit Care Med. 2014; 190: 922-929. (3) White PL, Jones T, Whittle K et al. Comparison of galactomannan enzyme immunoassay performance levels when testing serum and plasma samples. Clin Vaccine Immunol. 2013; 20: 636-638. (4) Eigl S, Prattes J, ReinwaldMet al. Influence of mould-active antifungal treatment on the performance of the Aspergillus-specific bronchoalveolar lavage fluid lateral-flow device test. Int J Antimicrob Agents. 2015; 46: 401-405. (5) Marr KA, Laverdiere M, Gugel A et al. Antifungal therapy decreases sensitivity of the Aspergillus galactomannan enzyme immunoassay. Clin Infect Dis. 2005; 40: 1762-1769. (6) Eigl S, Hoenigl M, Spiess B et al. Galactomannan testing and Aspergillus PCR in same-day brochoalveolar lavage and blood samples for diagnosis of invasive aspergillosis. Med Mycol. 2016; Epublication ahead of print. (7) https://www.ncbi.nlm.nih.gov/pubmed/?term=Reinwald%20M% 5BAuthor%5D{00AMP00}cauthor=true{00AMP00}cauthor_uid= 22740590, https://www.ncbi.nlm.nih.gov/pubmed/?term=Humme l%20M%5BAuthor%5D{00AMP00}cauthor=true{00AMP00}cauthor_ uid=22740590, https://www.ncbi.nlm.nih.gov/pubmed/?term= Kovalevskaya%20E%5BAuthor%5D{00AMP00}cauthor=true {00AMP00}cauthor_uid=22740590, et al. Therapy with antifungals decreases the diagnostic performance of PCR for diagnosing invasive aspergillosis in bronchoalveolar lavage samples of patients with haematological malignancies. https://www.ncbi.nlm.nih.gov/pubmed/ 22740590 2012; 67 (9): 2260-2267. 

2017

abstract No: 

S13.1

Full conference title: 

8th Trends in Medical Mycology, Organised under the auspices of EORTC-IDG and ECMM, 6-9 October 2017, Belgrade, Serbia
    • TIMM 8th (2017)