Metagenomic Next-Generation Sequencing of Cerebrospinal Fluid for the Diagnosis of Cerebral Aspergillosis

Abstract

Purpose: Cerebral aspergillosis (CA) is a rare but often fatal, difficult-to-diagnose, opportunistic infection. The utility of metagenomic next-generation sequencing (mNGS) for diagnosis of CA is unclear. We evaluated the usefulness of mNGS of the cerebrospinal fluid (CSF) for the diagnosis of CA. Methods: This prospective study involved seven consecutive patients with confirmed CA in whom CSF mNGS was performed. Serum (1→3)-β-D-glucan and galactomannan levels were determined, and histopathological examination and mNGS of the CSF were conducted. CSF specimens from three non-infected patients were used as positive controls. Results: mNGS of the CSF was positive in six of the seven confirmed CA cases (85.71% sensitivity). In the cryptococcal meningitis group (control), mNGS of the CSF was positive for Aspergillus in two patients (84.62% specificity). The positive likelihood ratio, negative likelihood ratio, and Youden's index of mNGS for CA in the CSF were 5.565, 0.169, and 0.7, respectively. Among the six mNGS-positive cases, more than two Aspergillus species were found in four (4/6, 66.67%). In the positive controls, the addition of one A. fumigatus spore yielded a standardised species-specific read number (SDSSRN) of 25.45 by mNGS; the detection rate would be 0.98 if SDSSRN was 2. Conclusion: mNGS facilitates the diagnosis of CA and may reduce the need for cerebral biopsy in patients with suspected CA. Trial Registration Number: Chinese Clinical Trial Registry, ChiCTR1800020442.

Keywords: cerebral aspergillosis; cerebrospinal fluid; diagnosis; metagenomic next-generation sequencing; pathogens.

FIGURE 1

Neuroimaging, mNGS results, and histopathological findings of case 4. T1-weighted MRI with contrast depicting a space-occupying lesion in the left sphenoid sinus and nasopharynx (A,B). The species-specific read numbers of Aspergillus versicolor and Aspergillus sydowii genomes were 20 and 11, with coverages of 0.0030 and 0.0015%, respectively (C,D). PAS stain demonstrating Aspergillus hyphae branching at 45°. Magnification, ×200 (E), ×400 (F).

FIGURE 2

Linear regression of SDSSRN versus the number of spores added. The linear regression has the function SDSSRN = 25.45 × (number of spores); the grey area corresponds to the 95% confidence level.

FIGURE 3

Detection probability with increasing SDSSRN. Bars were calculated as (1–0.15^SDSSRN).