Cryptococcosis in Acquired Immunodeficiency Syndrome Patients Clinically Confirmed and/or Diagnosed at Necropsy in a Teaching Hospital in Brazil

Determining Potential Link between Environmental and Clinical Isolates of Cryptococcus neoformans/Cryptococcus gattii Species Complexes Using Phenotypic and Genotypic Characterisation

Opportunistic infections due to Cryptococcus neoformans and C. gattii species complexes continue to rise unabated among HIV/AIDS patients, despite improved antifungal therapies. Here, we collected a total of 20 environmental and 25 presumptive clinical cryptococcal isolates from cerebrospinal fluid (CSF) samples of 175 patients enrolled in an ongoing clinical trial Ambition 1 Project (Botswana-Harvard Partnership). Identity confirmation of the isolates was done using MALDI-TOF MS and PCR. We describe the diversity of the isolates by PCR fingerprinting and sequencing (Oxford Nanopore Technology) of the intergenic spacer region. Mating types of the isolates were determined by amplification of the MAT locus. We report an unusual prevalence of 42.1% of C. neoformans x C. deneoformans hybrids Serotype AD (n = 16), followed by 39.5% of C. neoformans Serotype A (n = 15), 5.3% of C. deneoformans, Serotype D (n = 2), 7.9% of C. gattii (n = 3), and 5.3% of C. tetragattii (n = 2) in 38 representative isolates that have been characterized. Mating type-specific PCR performed on 38 representative environmental and clinical isolates revealed that 16 (42.1%) were MATa/MATα hybrids, 17 (44.7%) were MATα, and five (13.2%) possessed MATa mating type. We used conventional and NGS platforms to demonstrate a potential link between environmental and clinical isolates and lay a foundation to further describe mating patterns/history in Botswana.

CRYPTOCOCCOSIS: A bibliographic narrative review on antifungal resistance

Cryptococcosis is an infectious fungal disease widely studied for its epidemiological importance in the context of public health, given the high morbidity and mortality associated with this invasive fungal infection. Many cases of the disease present clinical resistance and progress to death, even in the presence of antifungal therapy. The prolonged use of triazole drugs to maintain the treatment of cryptococcosis in AIDS patients, can lead to selective pressure from mutant strains, among other resistance mechanisms, justifying the poor clinical evolution of some cases. In this study, a narrative review of the literature on the occurrence of antifungal resistance in cryptococcosis agents was performed. Publications from 2010 to 2022 that address this topic were selected using Google Scholars and Scopus website. Data from the studies were analyzed for the values of minimum inhibitory concentration (MIC) of drugs used in the management of cryptococcosis. The review showed that the highest MIC values occurred for voriconazole, especially against C. neoformans. It is concluded that there is a lack of studies with statistical analysis of the data obtained, in order to provide a better dimensioning of the resistance rates of cryptococcosis agents to different antifungal agents, both in geographical and temporal context.

Chronic disseminated cryptococcosis without meningeal involvement in a severely immunosuppressed HIV-infected patient successfully treated with fluconazole

A 43-year-old female with advanced HIV infection presented with two chronic skin lesions. Cutaneous cryptococcosis was confirmed and pulmonary cryptococcosis was suspected. The patient was neurologically asymptomatic and the cerebrospinal fluid cryptococcal antigen lateral flow assay was negative. She received oral fluconazole and had resolution of the skin lesions and significant improvement of the lung lesions. We report a person with AIDS with chronic disseminated cryptococcosis without meningeal involvement successfully treated with oral fluconazole.

Cryptococcus spp. and Cryptococcosis: focusing on the infection in Brazil

Cryptococcosis is a global fungal infection caused by the Cryptococcus neoformans/Cryptococcus gattii yeast complex. This infection is acquired by inhalation of propagules such as basidiospores or dry yeast, initially causing lung infections with the possibility of progressing to the meninges. This infection mainly affects immunocompromised HIV and transplant patients; however, immunocompetent patients can also be affected. This review proposes to evaluate cryptococcosis focusing on studies of this mycosis in Brazilian territory; moreover, recent advances in the understanding of its virulence mechanism, animal models in research are also assessed. For this, literature review as realized in PubMed, Scielo, and Brazilian legislation. In Brazil, cryptococcosis has been identified as one of the most lethal fungal infections among HIV patients and C. neoformans VNI and C. gattii VGII are the most prevalent genotypes. Moreover, different clinical settings published in Brazil were described. As in other countries, cryptococcosis is difficult to treat due to a limited therapeutic arsenal, which is highly toxic and costly. The presence of a polysaccharide capsule, thermo-tolerance, production of melanin, biofilm formation, mechanisms for iron use, and morphological alterations is an important virulence mechanism of these yeasts. The introduction of cryptococcosis as a compulsory notification disease could improve data regarding incidence and help in the management of these infections.

Disseminated Cryptococcal Infection in HIV-Infected Patients: A Retrospective Clinicopathological Review of 4 Autopsy Cases

Cryptococcosis is an opportunistic infection with high mortality if not diagnosed and treated in time. The objective of this study was to review the clinicopathological information of decendents with final autopsy diagnosis of disseminated cryptococcal infection. This study collected data from 4 decendents who presented to an academic hospital/laboratory between 1 January 2015 to 31 December 2018. Their clinical, radiological and pathological findings including treatment were reviewed. Two decendents presented with respiratory symptoms whilst the other 2 presented with meningeal symptoms. Three were confirmed HIV positive. One decendent was on ART, one had defaulted treatment and one was ART naïve. Two decendents were diagnosed with cryptococcal meningitis, one with bacterial pneumonia and one with pulmonary tuberculosis. Three decendents died in emergency unit and one in the ward whilst on antifungal therapy. The autopsy findings confirmed disseminated cryptococcal infection in all cases. A high index of suspicion should be maintained in the right clinical context. Multi-organ involvement should be suspected in all patients and be actively sought out.

Should we perform the serum cryptococcal antigen test in people living with HIV hospitalized due to a community-acquired pneumonia episode?

Community-acquired pneumonia (CAP) is a common cause of hospitalization among people living with human immunodeficiency virus (PLWH), particularly those with severe immunosuppression. Pulmonary disease due to cryptococcosis is uncommonly reported and likely under-diagnosed. There is scarce information about cryptococcal antigen (CrAg) prevalence in PLWH with CAP. The objectives of this study were to identify among PLWH who were hospitalized with CAP: (i) the prevalence of serum CrAg positivity, (ii) the proportion with asymptomatic vs. symptomatic cryptococcosis; and (iii) the prevalence of serum CrAg positivity in CD4+ T-cell count <100 cells/mm3. We performed a sub-analysis of a prospective cohort of hospitalized adults enrolled into a randomized clinical trial testing therapy for CAP. We included 202 participants who had serum CrAg testing performed. We found a 3.5% prevalence of serum CrAg-positivity overall, being higher (5.7%) in CD4+ T-cell count <100 cells/mm3. Overall, asymptomatic and symptomatic cryptococcosis were present in 2.0% and 1.5%, respectively. This study identifies a target population for CrAg testing: PLWH hospitalized with diagnosis of CAP, particularly those with CD4+ T-cell count <100 cells/mm3 where the number needed to test was 18 to detect 1 CrAg-positive person. This approach may facilitate the detection of asymptomatic cryptococcal infection and allow a timely diagnosis of symptomatic cryptococcal disease.

Clinical characteristics and cerebro-spinal fluid cytokine changes in patients with acquired immunodeficiency syndrome and central nervous system infection

Clinical characteristics and the cerebro-spinal fluid (CSF) cytokine changes in acquired immunodeficiency syndrome (AIDS) patients with tuberculous meningitis and cryptococcal meningitis in central nervous system (CNS) infections before and after treatment were investigated. The clinical records of 80 AIDS patients with CNS infections and 40 non-CNS infection patients hospitalized in the Infection Department of the First Hospital of Changsha from February 2013 to March 2016 were retrospectively analyzed. Forty-one cases of AIDS complicated with tuberculous meningitis were enrolled as group A, 39 cases of AIDS complicated with cryptococcal meningitis as group B, and 40 cases of non-CNS infection with lumbar puncture indication as group C. The general data, clinical symptoms, CSF examination and prognosis of the three groups of patients were collected. Of the 80 patients, 56 patients were discharged from hospital (improvement group) and 24 died (death group) after treatment. The concentrations of interferon-γ (IFN-γ), interleukin-6 (IL-6), interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α) in CSF were detected by enzyme-linked immunosorbent assay. There were significant differences in clinical manifestations, CSF pressure, CSF leucocyte count, CSF glucose, CSF chloride and CSF protein between group A, group B and group C (P<0.05). The concentrations of IFN-γ, IL-6, IL-10 and TNF-α in CSF of group A and group B increased significantly compared with group C (P<0.001). The IL-6, IL-10 and TNF-α levels in CSF in the improvement group were significantly lower than those in the death group (P<0.001), while the concentration of IFN-γ increased significantly (P<0.001). CSF biochemistry is characterized by increased pressure, leucocyte count and protein, and decreased chloride and glucose. IFN-γ, IL-6, IL-10 and TNF-α in CSF have certain predictive value for poor prognosis of AIDS patients with CNS infection.

Mortality due to Cryptococcus neoformans and Cryptococcus gattii in low-income settings: an autopsy study

Cryptococcosis is a major opportunistic infection and is one of the leading causes of death in adults living with HIV in sub-Saharan Africa. Recent estimates indicate that more than 130,000 people may die annually of cryptococcal meningitis in this region. Although complete diagnostic autopsy (CDA) is considered the gold standard for determining the cause of death, it is seldom performed in low income settings. In this study, a CDA was performed in 284 deceased patients from Mozambique (n = 223) and Brazil (n = 61). In depth histopathological and microbiological analyses were carried out in all cases dying of cryptococcosis. We determined the cryptococcal species, the molecular and sero-mating types and antifungal susceptibility. We also described the organs affected and reviewed the clinical presentation and patient management. Among the 284 cases included, 17 fatal cryptococcal infections were diagnosed. Cryptococcus was responsible for 16 deaths among the 163 HIV-positive patients (10%; 95%CI: 6-15%), including four maternal deaths. One third of the cases corresponded to C. gattii (VGI and VGIV molecular types, Bα and Cα strains) and the remaining infections typed were caused by C. neoformans var. Grubii (all VNI and Aα strains). The level of pre-mortem clinical suspicion was low (7/17, 41%), and 7/17 patients (41%) died within the first 72 hours of admission. Cryptococcosis was responsible for a significant proportion of AIDS-related mortality. The clinical diagnosis and patient management were inadequate, supporting the need for cryptococcal screening for early detection of the disease. This is the first report of the presence of C. gattii infection in Mozambique.

The status of cryptococcosis in Latin America

Cryptococcosis is a life-threatening fungal infection caused by the encapsulated yeasts Cryptococcus neoformans and C. gattii, acquired from the environment. In Latin America, as occurring worldwide, C. neoformans causes more than 90% of the cases of cryptococcosis, affecting predominantly patients with HIV, while C. gattii generally affects otherwise healthy individuals. In this region, cryptococcal meningitis is the most common presentation, with amphotericin B and fluconazole being the antifungal drugs of choice. Avian droppings are the predominant environmental reservoir of C. neoformans, while C. gattii is associated with several arboreal species. Importantly, C. gattii has a high prevalence in Latin America and has been proposed to be the likely origin of some C. gattii populations in North America. Thus, in the recent years, significant progress has been made with the study of the basic biology and laboratory identification of cryptococcal strains, in understanding their ecology, population genetics, host-pathogen interactions, and the clinical epidemiology of this important mycosis in Latin America.

Challenges in the Diagnosis of Invasive Fungal Infections in Immunocompromised Hosts

Purpose of review

The expanding population of immunocompromised patients coupled with the recognition of a growing number of different species of fungi responsible for diseases in such hosts makes the diagnosis of invasive fungal infection (IFI) a challenging task. The recent advances and challenges in the diagnosis of IFI in the setting of immunocompromised hosts are reviewed. The advantages and limitations of histopathology and the role of culture-independent methods, such as those based on the use of nucleic acids applied to fresh and formalin-fixed, paraffin-embedded sections, besides culture- and non-culture-based diagnostic methods, to obtain a timely and correct diagnosis of IFI are highlighted.

Recent findings

The therapeutic implications of identifying the genus and species of the fungus present in the specimen with the molecular diagnostics applied to tissue specimens are reviewed. No method alone is efficient in correctly identifying fungi and it is essential to combine the traditional histochemical staining with molecular methods to achieve a rapid and genus-/species-specific diagnosis of IFI.

Summary

We review the recent findings and challenges in the hystopathologic diagnosis of IFI in the setting of immunocompromised hosts. Non method alone is efficient in correctly identify fungi and pathologists should combine classic staining with molecular methods to achieve a rapid and genus/species fungal diagnosis.

Infective capacity of Cryptococcus neoformans and Cryptococcus gattii in a human astrocytoma cell line

Pathogenesis of cryptococcosis in the central nervous system (CNS) is a topic of ongoing research, including the mechanisms by which this fungus invades and infects the brain. Astrocytes, the most common CNS cells, play a fundamental role in the local immune response. Astrocytes might participate in cryptococcosis either as a host or by responding to fungal antigens. To determine the infectivity of Cryptococcus neoformans var. grubii and Cryptococcus gattii in a human astrocytoma cell line and the induction of major histocompatibility complex (MHC) molecules. A glioblastoma cell line was infected with C. neoformans var. grubii and C. gattii blastoconidia labelled with FUN-1 fluorescent stain. The percentage of infection and expression of HLA class I and II molecules were determined by flow cytometry. The interactions between the fungi and cells were observed by fluorescence microscopy. There was no difference between C. neoformans var. grubii and C. gattii in the percentage infection, but C. neoformans var. grubii induced higher expression of HLA class II than C. gattii. More blastoconidia were recovered from C. neoformans-infected cells than from C. gattii infected cells. Cryptococcus neoformans var. grubii may have different virulence mechanisms that allow its survival in human glia-derived cells.