Features of cryptococcosis among 652 HIV-seronegative individuals in France: a cross-sectional observational study (2005-2020)

OBJECTIVES

We aimed to describe features and outcomes of cryptococcosis among HIV-seronegative individuals in a large surveillance network for cryptococcosis in France.

METHODS

We included incident cases of cryptococcosis in HIV-seronegative individuals from 2005 to 2020. We compared patient characteristics, disease presentations, cryptococcal antigen results, and induction antifungal treatments according to underlying disease. We examined factors associated with 90-day mortality. Among patients with disseminated infections, we investigated whether receipt of flucytosine and polyene combination was associated with lower mortality.

RESULTS

Among 652 individuals, 209 (32.1%) had malignancy, 130 (19.9%) were solid-organ transplant recipients, 204 (31.3%) had other immunocompromising conditions, and 109 (16.7%) had no reported underlying factor. The commonest presentations were disseminated infections (63.3%, 413/652) and isolated pulmonary infections (25.3%, 165/652). Solid-organ transplant patients were most likely to have disseminated infections and a positive serum cryptococcal antigen result. Patients with malignancy were older and less likely to receive a flucytosine-containing regimen for disseminated infections than others (58.7%, 78/133 vs. 73.2%, 194/265; p 0.029). The crude 90-day case-fatality ratio was 27.2% (95% CI, 23.5%-31.1%). Age ≥60 years (aOR: 2.75 [1.78-4.26]; p < 0.001), meningitis/fungaemia (aOR: 4.79 [1.80-12.7]; p 0.002), and malignancy (aOR: 2.4 [1.14-5.07]; p 0.02) were associated with higher 90-day mortality. Receipt of flucytosine and polyene combination was associated with lower 90-day mortality (aOR: 0.40 [0.23-0.71]; p 0.002) in multivariable analysis and inverse probability of treatment weighted analysis (aOR: 0.45 [0.25-0.80]; p 0.006).

DISCUSSION

HIV-seronegative individuals with cryptococcosis comprise a wide range of underlying conditions with different presentations and outcomes, requiring a tailored approach to diagnosis and management.

Is the C-Terminal Domain an Effective and Selective Target for the Design of Hsp90 Inhibitors against Candida Yeast?

Improving the armamentarium to treat invasive candidiasis has become necessary to overcome drug resistance and the lack of alternative therapy. In the pathogenic fungus Candida albicans, the 90-kDa Heat-Shock Protein (Hsp90) has been described as a major regulator of virulence and resistance, offering a promising target. Some human Hsp90 inhibitors have shown activity against Candida spp. in vitro, but host toxicity has limited their use as antifungal drugs. The conservation of Hsp90 across all species leads to selectivity issues. To assess the potential of Hsp90 as a druggable antifungal target, the activity of nine structurally unrelated Hsp90 inhibitors with different binding domains was evaluated against a panel of Candida clinical isolates. The Hsp90 sequences from human and yeast species were aligned. Despite the degree of similarity between human and yeast N-terminal domain residues, the in vitro activities measured for the inhibitors interacting with this domain were not reproducible against all Candida species. Moreover, the inhibitors binding to the C-terminal domain (CTD) did not show any antifungal activity, with the exception of one of them. Given the greater sequence divergence in this domain, the identification of selective CTD inhibitors of fungal Hsp90 could be a promising strategy for the development of innovative antifungal drugs.

Neurocysticercosis Diagnosis in a Non-Endemic Country: France

Diagnosing neurocysticercosis (NCC) is difficult due to its variable clinical presentations and the different imaging techniques used to detect brain damage. This study aimed to evaluate the use of cerebrospinal fluid serology and PCR for diagnosing biological neurocysticercosis in a non-endemic country. We tested samples from patients living in France with suspected NCC and confirmed that 45 of the patients presented with the disease. A total of 89% of patients had previously traveled to countries where the disease was endemic. The sensitivity of Western blots compared to ELISA was not significantly different (80% vs. 60%) (p > 0.05), and neither was the sensitivity of Western blots vs. PCR (78% vs. 56%) (p > 0.05). The PCR sensitivity was 78% and 47% in definitive NCC and in probable NCC. PCR tests using cerebrospinal fluid should be considered as a diagnostic criterion for identifying NCC.

In vitro immune responses of human PBMCs against Candida albicans reveals fungal and leucocyte phenotypes associated with fungal persistence

Although there is a growing understanding of immunity against Candida albicans, efforts need to be pursued in order to decipher the cellular mechanisms leading to an uncontrolled immune response that eventually oppose disease eradication. We describe here significant intra- and inter-subject variations in immune response patterns of major human leucocyte subsets following an in vitro challenge with C. albicans clinical isolates. We also observed that there are Candida isolate-dependent changes in leucocyte phenotypes. Through a combination of multiple fungal growth and flow cytometric measurements, coupled to the tSNE algorithm, we showed that significant proliferation differences exist among C. albicans isolates, leading to the calculation of a strain specific persistent index. Despite substantial inter-subject differences in T cells and stability of myeloid cells at baseline, our experimental approach highlights substantial immune cell composition changes and cytokine secretion profiles after C. albicans challenge. The significant secretion of IL-17 by CD66+ cells, IFN-γ and IL-10 by CD4+ T cells 2 days after C. albicans challenge was associated with fungal control. Fungal persistence was associated with delayed secretion of IFN-γ, IL-17, IL-4, TNF-α and IL-10 by myeloid cells and IL-4 and TNF-α secretion by CD4+ and CD8+ T cells. Overall, this experimental and analytical approach is available for the monitoring of such fungal and human immune responses.