Cryptococcus deuterogattii VGIIa Infection Associated with Travel to the Pacific Northwest Outbreak Region in an Anti-Granulocyte-Macrophage Colony-Stimulating Factor Autoantibody-Positive Patient in the United States

Abstract

The region encompassing the Pacific Northwest (PNW), Vancouver Island, Oregon, and Washington has been the location of an ongoing Cryptococcus gattii outbreak since the 1990s, and there is evidence that the outbreak is expanding along the West Coast into California. Here we report a clinical case of a 69-year-old, HIV-negative man from North Carolina who was diagnosed with a fungal brain mass by magnetic resonance imaging (MRI) and pathology. He had traveled to Seattle and Vancouver 3 years earlier and to Costa Rica 4 months prior to presentation. Phenotypic evidence showed that the fungal mass isolated from the patient's brain represented C. gattii In agreement with the phenotypic results, multilocus sequence typing (MLST) provided genotypic evidence that assigned the infecting organism within the C. gattii species complex and to the C. deuterogattii VGIIa clade. Whole-genome sequencing revealed >99.99% identity with the C. deuterogattii reference strain R265, indicating that the infecting strain is derived from the highly clonal outbreak strains in the PNW. We conclude that the patient acquired the C. gattii infection during his travel to the region 3 years prior and that the infection was dormant for an extended period of time before causing disease. The patient tested positive for anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) autoantibodies, supporting earlier reports that implicate these autoantibodies as a risk factor associated with C. gattii infection.IMPORTANCE Mortality rates associated with C. gattii infections are estimated to be between 13% and 33%, depending on an individual's predisposition, and C. gattii has caused at least 39 deaths in the PNW region. There have been four other international travel cases reported in patients from Europe and Asia with travel history to the PNW, but this report describes the first North American traveler who acquired C. deuterogattii infection presenting within the United States and the first case of a C. deuterogattii outbreak infection associated with anti-GM-CSF autoantibodies. Early and accurate diagnoses are important for disease prevention and treatment and for control of infectious diseases. Continual reporting of C. deuterogattii infections is necessary to raise awareness of the ongoing outbreak in the PNW and to alert travelers and physicians to the areas of endemicity with potential risks.

Keywords: Cryptococcus deuterogattii; anti-GM-CSF autoantibodies; travel-acquired cryptococcal meningitis.

FIG 1

Changes in parietal lobe lesions on brain MRI over the course of treatment. The top panels represent post-gadolinium T1-weighted images, and the bottom panels represent post-gadolinium T2-weighted images. (A) MRI at initial presentation. Circumferential ring enhancement on the post-gadolinium T1-weighted axial image and increased signal surrounding the lesion on the axial T2-fluid attenuation inversion recovery (FLAIR) image represent marked vasogenic edema (arrow). The heterogeneously increased signal within the cavity of the lesions represents necrosis. (B) MRI following 1 month of induction therapy. Increased T2 signal within the lesion cavity on the FLAIR sequence and increased surrounding edema and the overall size of the right parietal lesion indicate an interval of worsening with likely progressive necrosis of brain tissue (arrow). A leftward midline shift was noted. (C) MRI following resection of the right parietal lesion. Note improvement in the edema surrounding the lesion on the FLAIR sequence and an interval of decrease in the size of the right parietal lesion (arrow). (D) Subsequent MRI imaging after a total of 10 months of treatment. Improved T2/FLAIR signal abnormality with a decrease in the size of the resection cavity (arrow) as well as decrease in the size of the other visible lesions was observed.

FIG 2

Cryptococcal organisms can be visualized within the brain parenchyma of both intraoperative and fixed tissues. (A) Intraoperative touch preparation/smear depicting classic “soap bubble” lesions comprised of yeast cells within clear gelatinous capsules infiltrating the brain parenchyma. An absence of inflammatory cells was noted; the lack of an appreciable inflammatory response is characteristic of many cryptococcal infections. The scale bar represents 100 μm. (B) An intraoperative frozen section demonstrated spherical-to-oval, variably sized, encapsulated yeast cells. The organisms were refractile, and many had circumferential halos. The scale bar represents 100 μm. (C) Low-magnification image of periodic acid-Schiff (PAS) staining showing infiltration of brain parenchyma by positively staining yeast cells, morphologically consistent with Cryptococcus. The scale bar represents 200 μm. (D) Higher magnification of the image in panel C highlighting the refractile appearance and the intensely stained mucopolysaccharide capsule of the yeast forms in tissue sections. Of note, mucicarmine and alcian blue also showed positive staining in the capsule of cryptococcal organisms (not shown). The scale bar represents 100 μm. (E) Low-magnification image of Grocott-Gomori’s methenamine silver (GMS) staining showing a representative field with innumerable yeast cells, some with narrow-based budding. The scale bar represents 500 μm. (F) Higher magnification of the image in panel E illustrating the intense staining of organisms within the brain parenchyma (stained light green by the counterstain). The scale bar represents 100 μm.

FIG 3

The clinical isolate displays phenotypes consistent with a C. gattii MATα isolate. (A) Phenotypic testing of the isolate on YPD; niger seed; Christensen’s agar; and canavanine, glycine, and bromothymol blue (CGB) media. Section 1, S1 (Saccharomyces cerevisiae); section 2, H99 (C. neoformans); section 3, R265 (C. deuterogattii); section 4, clinical isolate thick streak (SEC744); section 5, clinical isolate single colony 1; section 6, clinical isolate single colony 2; section 7, clinical isolate single colony 3. (B) Capsule staining with India ink. Scale bars represent 5 μm. (C) Imaging of mating patches of the clinical isolate (SEC744) tested against R265 MATa and R265 MATα. R265 MATa × MATα served as a positive control. Arrows indicate mating structures visible by light microscopy at ×20 magnification. Scale bars represent 100 μm.

FIG 4

Genotyping places the clinical isolate in the C. deuterogattii VGIIa major lineage. (A) Representative MLST tree of TEF1. The scale bar represents the number of substitutions per site. (B) Allele designations for the SEC744 clinical isolate and the C. deuterogattii VGIIa, VGIIb, and VGIIc lineages. (C) FACS analysis of C. deuterogattii R265 (haploid control), RBB59 (C. gattii diploid), and the SEC744 clinical isolate. PI-A, propidium iodide area. (D) Testing for hypermutator phenotype in R265, the msh2Δ mutant, and the SEC744 clinical isolate.

FIG 5

Phylogenetic analysis suggests that the clinical isolate originated in the PNW. (A) Phylogenetic tree depicting association of the SEC744 clinical isolate with other C. deuterogattii VGIIa outbreak strains from the PNW. Numbers on branches represent the number of SNPs distinguishing the groups. (B) Venn diagram illustrating the SNPs found in the SEC744 clinical isolate compared to the outbreak VGIIa R265 reference strain. (C) Table classifying the location and nature of the 10 private SNPs in the SEC744 clinical isolate. CoA, coenzyme A; ID, identifier.