Most cited article - PubMed ID 35942851
Siderophores: a potential role as a diagnostic for invasive fungal disease
Advances in the early diagnosis of systemic mycoses are urgently needed, given the morbidity and mortality of such infections and the correlation between delays in treatment and poor outcomes. We demonstrated the prospective application of liquid chromatography-mass spectrometry in the diagnosis of a mixed fungal infection. In this study, we compared the performance of chest radiography, galactomannan (sGM), and beta-d-glucan (sBDG) serology with a novel diagnostic method based on creatinine-indexed microbial siderophores in urine. A woman with angioblastic T-cell lymphoma presented with neutropenia following allogeneic transplantation. sGM and sBDG remained positive throughout the 28-day intensive care unit stay. A. fumigatus DNA was detected in the induced sputum samples on sampling days 0 and 18. On day 18, a CT scan showed a typical nest sign, and R. microsporus DNA was detected in sputum. The patient was discharged from the hospital on day 28 and expired 7 days later. With our novel strategy based on mass spectrometry, A. fumigatus was consistently detected in the urine from day 0 to the end of the stay by the detection of triacetylfusarinine C (uTafC), an A. fumigatus-specific hydroxamate siderophore. An additional invasive R. microsporus infection was revealed by the detection of a mucoromycete-specific carboxylate siderophore in urine, rhizoferrin (uRhf), from day seven onward. Both creatinine-normalized siderophore indices (uTafC/Cr, uRhf/Cr) were sensitive to antifungal therapy and correlated with fast relapses of the invasive disease in time. This study illustrates how such an early and specific new approach can unravel the complexities of dual fungal infections.
- Publication type
- Journal Article MeSH
Scedosporium apiospermum and Lomentospora prolificans secrete siderophores (iron scavengers) during hyphal proliferation. Siderophores are virulence factors and potential clinical biomarkers of invasive scedosporiosis and lomentosporiosis. Both strains secreted a uniform spectrum of siderophores, including coprogen B (CopB), N α-methyl-coprogen B, dimethyl-coprogen, and ferricrocin, with N α-methyl-coprogen B being the fastest secreted and most abundant coprogen. Under iron and zinc restriction, reflecting a nutrient-limited host environment, L. prolificans secreted 45 times more CopB than did S. apiospermum, presumably contributing to its higher virulence. This robust mobilization of CopB was further enhanced by zinc surplus. Additionally, two novel cyclic peptides, Scedocyclin A and B, were characterized inScedosporium boydii using the de novo sequencing tool CycloBranch. Utilizing matrix-assisted laser desorption/ionization, the portfolio of coprogens detected had limits of detection and quantitation of 4.9 and 14.6 fmol/spot in complex matrices, respectively, making them strong candidates for the next-generation, routine diagnosis of invasive scedosporiosis and lomentosporiosis through the Biotyper siderotyping.
- Publication type
- Journal Article MeSH
Aspergillus fumigatus has been designated by the World Health Organization as a critical priority fungal pathogen. Some commercially available diagnostics for many forms of aspergillosis rely on fungal metabolites. These encompass intracellular molecules, cell wall components, and extracellular secretomes. This review summarizes the shortcomings of antibody tests compared to tests of fungal products in body fluids and highlights the application of β-d-glucan, galactomannan, and pentraxin 3 in bronchoalveolar lavage fluids. We also discuss the detection of nucleic acids and next-generation sequencing, along with newer studies on Aspergillus metallophores.
- Keywords
- PCR, aspergillosis, bronchoalveolar lavage fluid, galactomannan, lateral flow, metagenomic next-generation sequencing, metallophore, serum assays, siderophore, β-d-glucan,
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- Journal Article MeSH
- Review MeSH
Germination from conidia to hyphae and hyphal propagation of Aspergillus fumigatus are the key pathogenic steps in the development of invasive pulmonary aspergillosis (IPA). By applying in vitro observations in a clinical study of 13 patients diagnosed with probable IPA, here, we show that the transition from colonization to the A. fumigatus invasive stage is accompanied by the secretion of triacetylfusarinine C (TafC), triacetylfusarinine B (TafB), and ferricrocin (Fc) siderophores into urine, with strikingly better sensitivity performance than serum sampling. The best-performing index, the TafC/creatinine index, with a median value of 17.2, provided 92.3% detection sensitivity (95% confidence interval [CI], 64.0 to 99.8%) and 100% specificity (95% CI, 84.6 to 100%), i.e., substantially better than the corresponding indications provided by galactomannan (GM) and β-d-glucan (BDG) serology. For the same patient cohort, the serum GM and BDG sensitivities were 46.2 and 76.9%, respectively, and their specificities were 86.4 and 63.6%, respectively. The time-dependent specific appearance of siderophores in the host's urine represents an impactful clinical diagnostic advantage in the early discrimination of invasive aspergillosis from colonization. A favorable concentration of TafC in a clinical specimen distant from a deep infection site enables the noninvasive sampling of patients suffering from IPA. IMPORTANCE The importance of this research lies in the demonstration that siderophore analysis can distinguish between asymptomatic colonization and invasive pulmonary aspergillosis. We found clear associations between phases of fungal development, from conidial germination to the proliferative stage of invasive aspergillosis, and changes in secondary metabolite secretion. The critical extracellular fungal metabolites triacetylfusarinines C and B are produced during the polarized germination or postpolarized growth phase and reflect the morphological status of the proliferating pathogen. False positivity in Aspergillus diagnostics is minimized as mammalian cells do not synthesize Aspergillus siderophore or mycotoxin molecules.
- Keywords
- Aspergillus fumigatus, colonization, invasive pulmonary aspergillosis, iron metabolism, mass spectrometry, noninvasive diagnosis, siderophore, urine analysis,
- Publication type
- Journal Article MeSH
Invasive pulmonary aspergillosis (IPA) may be a rare cause of granulomatous pneumonia in horses. The mortality of IPA is almost 100%; direct diagnostic tools in horses are needed. Bronchoalveolar lavage fluid (BALF) and serum samples were collected from 18 horses, including individuals suffering from IPA (n = 1), equine asthma (EA, n = 12), and 5 healthy controls. Serum samples were collected from another 6 healthy controls. Samples of BALF (n = 18) were analyzed for Aspergillus spp. DNA, fungal galactomannan (GM), ferricrocin (Fc), triacetylfusarinin C (TafC), and gliotoxin (Gtx). Analysis of 24 serum samples for (1,3)-β-D-glucan (BDG) and GM was performed. Median serum BDG levels were 131 pg/mL in controls and 1142 pg/mL in IPA. Similar trends were observed in BALF samples for GM (Area under the Curve (AUC) = 0.941) and DNA (AUC = 0.941). The fungal secondary metabolite Gtx was detected in IPA BALF and lung tissue samples (86 ng/mL and 2.17 ng/mg, AUC = 1).
