Cryptococcosis in the era of AIDS--100 years after the discovery of Cryptococcus neoformans

Cryptococcal meningitis due to Cryptococcus neoformans VNI in a koala (Phascolarctos cinereus) with progressive neurological disease

Nearly all cases of cryptococcosis in koalas are caused by Cryptococcus gattii species complex. A rare case of meningitis due to Cryptococcus neoformans VNI/AFLP1 (abbreviated VNI) is described in a koala with nasal colonisation by both species complexes. An eight-year-old koala in a wildlife park presented for seizures and returned a positive latex cryptococcal antigen agglutination test. The koala was euthanased due to the severity of disease, and a post-mortem computed tomography study showed mild mucosal thickening of the right nasal turbinates. The necropsy also showed slightly turbid cisternal cerebrospinal fluid and meningeal opacity. Histology revealed severe granulomatous cryptococcal meningitis and paucireactive right cryptococcal rhinitis. Fungal cultures yielded heavy pure growths of C. neoformans from the brain and spinal cord, and comparable heavy growths of both C. neoformans and C. gattii from the nasal cavity. Cryptococcus species complexes were identified by mass spectrometry (MALDI-TOF) and multi-locus sequence typing (MLST). The C. neoformans isolates from the brain, spinal cord and nasal cavity were identical by MLST and classified as sequencing type (ST) 23 and molecular type (MT) VNI. The C. gattii isolates were classified as ST 51 and AFLP4/VGI (abbreviated VGI). This suggests that the meningitis developed as an extension of C. neoformans VNI from nasal cavity colonisation. This is the second documented case of central nervous system (CNS) cryptococcosis due to C. neoformans species complex in a koala and the first in Australia. Despite heavy nasal colonisation by C. gattii, only the C. neoformans isolate progressed to meningitis.

Vacuolar sterol β-glucosidase EGCrP2/Sgl1 deficiency in Cryptococcus neoformans: Dysfunctional autophagy and Mincle-dependent immune activation as targets of novel antifungal strategies

Cryptococcus neoformans (Cn) is a fungal pathogen responsible for cryptococcal meningitis, which accounts for 15% of AIDS-related deaths. Recent studies have shown that the absence of sterol β-glucosidase (EGCrP2, also known as Sgl1) in Cn significantly attenuates its virulence in a mouse infection model. However, the mechanisms underlying this virulence attenuation remain unclear. In this study, we observed a significant increase in dead cells after 3 days of culture of SGL1-deficient Cn (sgl1Δ, KO) at 37°C, compared with wild-type (WT) and SGL1-reconstituted Cn (sgl1Δ::SGL1, RE). qPCR analysis of WT, KO, and RE strains indicated that autophagy-related genes (ATGs) were significantly downregulated in KO strain. Atg8-dependent GFP translocation to the vacuole was significantly delayed in KO strain under starvation conditions. This autophagy dysfunction was identified as the primary cause of the increased cell death observed in KO strain under nitrogen starvation conditions at 37°C. EGCrP2/Sgl1 is predominantly localized in the vacuoles of Cn, and its deletion results in the accumulation of not only ergosterol β-glucoside (EG), as previously reported, but also acylated EGs (AEGs). AEGs were much more potent than EG in activating the C-type lectin receptor Mincle in mice, rats, and humans. AEGs were released from KO strain via extracellular vesicles (EVs). Chemically synthesized 18:1-EG and EVs derived from KO strain, but not WT or RE strains, enhanced cytokine production in murine and human dendritic cells. AEG-dependent cytokine production was markedly reduced in dendritic cells from Mincle-deficient mice, and the number of KO strain in lung tissue from Mincle-deficient mice was substantially higher than wild-type mice on day 3 after infection. Intranasal administration of acylated sitosterol β-glucoside increased Mincle expression and cytokine production and reduced the Cn burden in lung tissue of Cn-infected mice. These findings suggest that autophagy dysfunction in KO strain and the host innate immune response via the AEG-dependent Mincle activation are critical in reducing Cn virulence in mice.

Massive Gene Loss in the Fungus Sporothrix epigloea Accompanied a Shift to Life in a Glucuronoxylomannan-based Gel Matrix

Fungi are well-known for their ability to both produce and catabolize complex carbohydrates to acquire carbon, often in the most extreme of environments. Glucuronoxylomannan (GXM)-based gel matrices are widely produced by fungi in nature and though they are of key interest in medicine and pharmaceuticals, their biodegradation is poorly understood. Though some organisms, including other fungi, are adapted to life in and on GXM-like matrices in nature, they are almost entirely unstudied, and it is unknown if they are involved in matrix degradation. Sporothrix epigloea is an ascomycete fungus that completes its life cycle entirely in the short-lived secreted polysaccharide matrix of a white jelly fungus, Tremella fuciformis. To gain insight into how S. epigloea adapted to life in this unusual microhabitat, we compared the predicted protein composition of S. epigloea to that of 21 other Sporothrix species. We found that the genome of S. epigloea is smaller than that of any other sampled Sporothrix, with widespread functional gene loss, including those coding for serine proteases and biotin synthesis. In addition, many predicted CAZymes degrading both plant and fungal cell wall components were lost while a lytic polysaccharide monooxygenase with no previously established activity or substrate specificity, appears to have been gained. Phenotype assays suggest narrow use of mannans and other oligosaccharides as carbon sources. Taken together, the results suggest a streamlined machinery, including potential carbon sourcing from GXM building blocks, facilitates the hyperspecialized ecology of S. epigloea in the GXM-like milieu.

Disseminated Cryptococcal Gattii infection in a patient with anti-granulocyte-macrophage colony-stimulating-factor autoantibody: a case report

BACKGROUND

Cryptococcosis is an opportunistic fungal infection in immunocompromised patients. The major species include Cryptococcus grubii, Cryptococcus neoformans, and rarely, Cryptococcus gattii. Here we present a disseminated Cryptococcus gattii infection in a patient with elevated granulocyte-macrophage colony-stimulating-factor autoantibody which was successfully treated with antifungal therapy.

CASE PRESENTATION

A 61-year-old healthy man presented with a 3-week history of blurred vision, low-grade fever, headache, and a one-year history of low back pain following a fall on his farm. Physical examination revealed lower back tenderness and diplopia. He was tested negative for hepatitis B, C, and human immunodeficiency virus. Chest X-ray revealed a focal opacity in the right retrocardiac paraspinal region and pleural effusion. Magnetic resonance imaging showed a mass located at the L1 prevertebral region and multiple rim-enhancing lesions in bilateral cerebral hemispheres. Thoracoscopy demonstrated cystic lesions at the right costopleural angle. Pathology and microbiology studies confirmed the diagnosis of disseminated Cryptococcus gatti infection. Autoantibodies to granulocyte-macrophage colony-stimulating factor were detected and were considered to cause disseminated cryptococcosis. The patient was started on amphotericin B followed by fluconazole treatment. One month later, the symptoms ameliorated and repeated image studies after 1 year of follow-up showed the resolution of lesions.

CONCLUSION

This report describes the first case of disseminated Cryptococcus gattii infection involving the musculoskeletal system, respiratory system, and central nervous system with granulocyte-macrophage colony-stimulating-factor autoantibody by evidence of histology and microbiology.

Roles of Different Signaling Pathways in Cryptococcus neoformans Virulence

Cryptococcus neoformans is a widespread fungal pathogen that can infect the human central nervous system (CNS) and cause fungal meningitis, leading to hundreds of thousands of deaths worldwide each year. Previous studies have demonstrated that many signal transduction pathways are crucial for the morphological development and virulence of C. neoformans. In this review, data from over 116 research articles have been compiled to show that many signaling pathways control various characteristics of C. neoformans, individually or in association with other pathways, and to establish strong links among them to better understand C. neoformans pathogenesis. Every characteristic of C. neoformans is closely linked to these signaling pathways, making this a rich area for further research. It is essential to thoroughly explore these pathways to address questions that remain and apply a molecular mechanistic approach to link them. Targeting these pathways is crucial for understanding the exact mechanism of infection pathogenesis and will facilitate the development of antifungal drugs as well as the diagnosis and prevention of cryptococcosis.

Disseminated Cryptococcus infection presenting as lytic skeletal lesions suggesting bony metastatic disease

A 76-year-old male diagnosed with sarcoidosis presented with atraumatic left anterior knee pain. Initial imaging of the left lower extremity revealed an eccentrically-based lytic lesion in the mid-distal femur with cortical erosion and an additional lytic lesion in the proximal tibia. Magnetic resonance imaging (MRI) demonstrated an aggressive lesion in the proximal tibia with surrounding marrow edema, cortical breach, and erosion into the distal patellar tendon. Given concern for metastatic bone lesions, a18-fluorodeoxyglucose positron emission tomography/computed tomography scan (FDG PET/CT) was performed which demonstrated concordant hypermetabolic lytic lesions at the left mid-distal femur and the left proximal tibia, as well as hypermetabolic diffuse lymphadenopathy. The patient was presumed to have metastatic lung cancer based on the presence of lung nodules. Due to concern for impending pathologic fracture, the patient underwent open biopsy with a plan for prophylactic fixation of both lesions. Intra-operatively, however, both lesions were found to contain pus, from which cultures ultimately grew Cryptococcus neoformans. This is a case of disseminated skeletal cryptococcosis masquerading as metastatic cancer in a patient without classic risk factors for disseminated cryptococcosis (defined as extrapulmonary evidence of infection). Classically, disseminated cryptococcosis is thought to occur in severely immunocompromised patients, such as those with human immunodeficiency virus (HIV) or organ transplant recipients. This case highlights the need to maintain a high index of suspicion in patients with underlying immunocompromising conditions, including less common conditions such as sarcoid, who present with bony lesions. This case report then discusses the diagnostic evaluation and treatment of disseminated skeletal cryptococcosis.

With age comes resilience: how mitochondrial modulation drives age-associated fluconazole tolerance in Cryptococcus neoformans

Cryptococcus neoformans (Cn) is an opportunistic fungal microorganism that causes life-threatening meningoencephalitis. During the infection, the microbial population is heterogeneously composed of cells with varying generational ages, with older cells accumulating during chronic infections. This is attributed to their enhanced resistance to phagocytic killing and tolerance of antifungals like fluconazole (FLC). In this study, we investigated the role of ergosterol synthesis, ATP-binding cassette (ABC) transporters, and mitochondrial metabolism in the regulation of age-dependent FLC tolerance. We find that old Cn cells increase the production of ergosterol and exhibit upregulation of ABC transporters. Old cells also show transcriptional and phenotypic characteristics consistent with increased metabolic activity, leading to increased ATP production. This is accompanied by increased production of reactive oxygen species, which results in mitochondrial fragmentation. This study demonstrates that the metabolic changes occurring in the mitochondria of old cells drive the increase in ergosterol synthesis and the upregulation of ABC transporters, leading to FLC tolerance.

IMPORTANCE

Infections caused by Cryptococcus neoformans cause more than 180,000 deaths annually. Estimated 1-year mortality for patients receiving care ranges from 20% in developed countries to 70% in developing countries, suggesting that current treatments are inadequate. Some fungal cells can persist and replicate despite the usage of current antifungal regimens, leading to death or treatment failure. Aging in fungi is associated with enhanced tolerance against antifungals and resistance to killing by host cells. This study shows that age-dependent increase in mitochondrial reactive oxygen species drive changes in the regulation of membrane transporters and ergosterol synthesis, ultimately leading to the heightened tolerance against fluconazole in old C. neoformans cells. Understanding the underlying molecular mechanisms of this age-associated antifungal tolerance will enable more targeted antifungal therapies for cryptococcal infections.

The Role of Ficolins in Lung Injury

BACKGROUND

Respiratory diseases seriously threaten human health worldwide, and lung injury is an important component of respiratory disease. Complement activation is an important function of the innate immune system. Complement activation helps the body defend against invasion by external microorganisms, whereas excessive complement activation can exacerbate tissue damage or lead to unwanted side effects. Ficolins are a class of immune-related proteins in the lectin pathway that play important roles in the body's immune defense. Although individual ficolins are not well understood, current information suggests that ficolins may play an important regulatory role in lung injury.

SUMMARY

Several studies have shown that ficolins are involved in the immune response in the lung, particularly in the response to infectious and inflammatory processes.

KEY MESSAGES

This review summarizes the role of ficolins in lung injury. Ficolins may influence the development and repair of lung injury by recognizing and binding pathogenic microorganisms, modulating the inflammatory response, and promoting the clearance of immune cells. In addition, ficolins are associated with the development and progression of lung diseases (such as pneumonia and ARDS) and may have an important impact on the pathophysiological processes of inflammatory diseases.

Infectious factors in myocarditis: a comprehensive review of common and rare pathogens

BACKGROUND

Myocarditis is a significant health threat today, with infectious agents being the most common cause. Accurate diagnosis of the etiology of infectious myocarditis is crucial for effective treatment.

MAIN BODY

Infectious myocarditis can be caused by viruses, prokaryotes, parasites, and fungi. Viral infections are typically the primary cause. However, some rare opportunistic pathogens can also damage heart muscle cells in patients with immunodeficiencies, neoplasms and those who have undergone heart surgery.

CONCLUSIONS

This article reviews research on common and rare pathogens of infectious myocarditis, emphasizing the complexity of its etiology, with the aim of helping clinicians make an accurate diagnosis of infectious myocarditis.

Achieving Resilience in Aging: How Mitochondrial Modulation Drives Age-associated Fluconazole Tolerance in Cryptococcus neoformans

Cryptococcus neoformans ( Cn ) is an opportunistic fungal microorganism that causes life-threatening meningoencephalitis. During the infection, the microbial population is heterogeneously composed of cells with varying generational ages, with older cells accumulating during chronic infections. This is attributed to their enhanced resistance to phagocytic killing and tolerance of antifungals like fluconazole (FLC). In this study, we investigated the role of ergosterol synthesis, ATP-binding cassette (ABC) transporters, and mitochondrial metabolism in the regulation of age-dependent FLC tolerance. We find that old Cn cells increase the production of ergosterol and exhibit upregulation of ABC transporters. Old cells also show transcriptional and phenotypic characteristics consistent with increased metabolic activity, leading to increased ATP production. This is accompanied by increased production of reactive oxygen species (ROS), which results in mitochondrial fragmentation. This study demonstrates that the metabolic changes occurring in the mitochondria of old cells drive the increase in ergosterol synthesis and the upregulation of ABC transporters, leading to FLC tolerance.

IMPORTANCE

Infections caused by Cryptococcus neoformans cause more than 180,000 deaths annually. Estimated one-year mortality for patients receiving care ranges from 20% in developed countries to 70% in developing countries, suggesting that current treatments are inadequate. Some fungal cells can persist and replicate despite the usage of current antifungal regimens, leading to death or treatment failure. In replicative aging, older cells display a resilient phenotype, characterized by their enhanced tolerance against antifungals and resistance to killing by host cells. This study shows that age-dependent increase in mitochondrial reactive oxygen species drive changes in ABC transporters and ergosterol synthesis, ultimately leading to the heightened tolerance against fluconazole in old C. neoformans cells. Understanding the underlying molecular mechanisms of this age-associated antifungal tolerance will enable more targeted antifungal therapies for cryptococcal infections.

Recurrent Cryptococcal Meningitis in a Late Presenter of HIV: A Rare Case Report and Review of Literature

BACKGROUND The highly active antiretroviral treatment (HAART) and the primary prophylaxis in newly diagnosed people living with HIV (PLHIV) have reduced the incidence of opportunistic infections such as cryptococcal meningitis (CM). Relapse of CM is associated with increased morbidity and mortality. The aim of the present case presentation is to report the clinical progress relapse of CM in a man who was a late presenter PLHIV, 1 year after ART initiation with increased CD4 cell count, undetectable viral load, and excellent compliance after disruption of secondary antifungal prophylaxis. CASE REPORT One year after initial diagnosis of HIV and CM, the patient had no neurological or other symptoms, and viral suppression and increased CD4 cell count were achieved. After the completion of 12 months of secondary prophylaxis with fluconazole, an episode of partial seizure with secondary generalization occurred, followed by a short-term memory loss. Magnetic resonance imaging (MRI) indicated a focal lesion in right frontal-parietal brain region. Lumbar puncture was conducted and Cryptococcus neoformans non-resistant to fluconazole was isolated. He received antiepileptic treatment, induction antifungal treatment with liposomal amphotericin and fluconazole, consolidation treatment with fluconazole, and secondary prophylaxis with fluconazole, as in the first episode of CM. One year after the relapse, antiepileptic treatment and secondary prophylaxis with fluconazole continues and no new episode has been reported. The diagnosis of immune reconstitution inflammatory syndrome (IRIS)-related relapse of CM cannot be excluded. CONCLUSIONS Further studies are needed for the evaluation of parameters such as duration of secondary prophylaxis and treatment options for induction and consolidation therapy to reduce the relapse rate of CM.

Macropinocytosis as a potential mechanism driving neurotropism of Cryptococcus neoformans

Cryptococcus neoformans can invade the central nervous system by crossing the blood-brain barrier via a transcellular mechanism that relies on multiple host factors. In this narrative, we review the evidence that a direct interplay between C. neoformans and brain endothelial cells forms the basis for invasion and transmigration across the brain endothelium. Adherence and internalization of C. neoformans is dependent on transmembrane proteins, including a hyaluronic acid receptor and an ephrin receptor tyrosine kinase. We consider the role of EphA2 in facilitating the invasion of the central nervous system by C. neoformans and highlight experimental evidence supporting macropinocytosis as a potential mechanism of internalization and transcytosis. How macropinocytosis might be conclusively demonstrated in the context of C. neoformans is also discussed.

Direct antimicrobial effects of chemokines on Cryptococcus spp, with special emphasis on a 'CXC' chemokine

Cryptococcus species are ingenious human pathogens that are widespread globally. They continue to cause over 200,000 deaths per year. Presently due to the rise in resistance and therapy failure, it is necessary to shift the focus to an alternate therapeutic strategy against this pathogen. One promising approach is to emphasize the host defense system in order to develop more precise and customized treatment strategies. In this regard, research has revealed that interferon-γ-inducible CXCL10 chemokine, amongst other chemokines spanning both CXC and CC categories, has a direct killing effect in vitro against Cryptococcus neoformans and Cryptococcus gattii, with a significantly greater microbicidal effect against the former. Moreover, when CXCL10 is used in combination with CCL5, there is a significant reduction in the survival of C. gattii at normal-serum level concentration, indicating a previously unreported synergistic effect of these two chemokines. Confocal and STED microscopic studies have demonstrated that CXCL10 has both cell wall/membrane and intracellular targets against this fungus. These findings present new possibilities for developing chemokine-derived small molecule antifungals and may represent a step forward in creating precision medicine tailored to each patient.

Seasonality and meteorological factors of HIV-negative cryptococcal meningitis in Guangdong Province, China

OBJECTIVE

Information about the seasonal characteristics of human immunodeficiency virus (HIV)-negative cryptococcal meningitis (CM) is quite limited. The aim of this study was to explore the seasonality and meteorological factors of HIV-negative patients with CM.

METHODS

We performed a retrospective study of 469 HIV-negative CM patients admitted to the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong Province, China. Their initial onset symptoms of CM occurred from January 2011 to December 2020. The temperature, precipitation, sunlight, humidity and wind speed for the corresponding period and the associated topographic, ecological type and soil type parameters data were collected. The Poisson regression model was used to determine the meteorological factors associated with CM onset. The geographical detector method was used to detect other environmental factors associated with CM onset.

RESULTS

CM onset did not showed a seasonal fluctuation, but was strongly associated with mean temperature (β = .010, p = .028) and mean relative humidity (β = -.011, p = .006). In the rainy season, only mean wind speed remained significantly associated with CM onset (β = -.108, p = .041). In the dry season, mean temperature (β = .014, p = .016), mean relative humidity (β = -.016, p = .006) and hours of sunlight (β = -.002, p = .016) were significantly associated with CM onset. Topographic, ecological type and soil type factors did not add explanatory power.

CONCLUSIONS

Our findings add the knowledge about the environmental factors of HIV-negative CM. Meteorological factors, especially temperature and humidity, may be the main environmental factors affecting the onset of HIV-negative CM.

Inbred SJL mice recapitulate human resistance to Cryptococcus infection due to differential immune activation

IMPORTANCE

Cryptococcosis studies often utilize the common C57BL/6J mouse model. Unfortunately, infection in these mice fails to replicate the basic course of human disease, particularly hampering immunological studies. This work demonstrates that SJL/J mice can recapitulate human infection better than other mouse strains. The immunological response to Cryptococcus infection in SJL/J mice was markedly different from C57BL/6J and much more productive in combating this infection. Characterization of infected mice demonstrated strain-specific genetic linkage and differential regulation of multiple important immune-relevant genes in response to Cryptococcus infection. While our results validate many of the previously identified immunological features of cryptococcosis, we also demonstrate limitations from previous mouse models as they may be less translatable to human disease. We concluded that SJL/J mice more faithfully recapitulate human cryptococcosis serving as an exciting new animal model for immunological and genetic studies.

Pharmacodynamics of ATI-2307 in a rabbit model of cryptococcal meningoencephalitis

Cryptococcal meningoencephalitis (CM) is a devastating fungal disease with high morbidity and mortality. The current regimen that is standard-of-care involves a combination of three different drugs administered for up to one year. There is a critical need for new therapies due to both toxicity and inadequate fungicidal activity of the currently available antifungal drugs. ATI-2307 is a novel aryl amidine that disrupts the mitochondrial membrane potential and inhibits the respiratory chain complexes of fungi-it thus represents a new mechanism for direct antifungal action. Furthermore, ATI-2307 selectively targets fungal mitochondria via a fungal-specific transporter that is not present in mammalian cells. It has very potent in vitro anticryptococcal activity. In this study, the efficacy of ATI-2307 was tested in a rabbit model of CM. ATI-2307 demonstrated significant fungicidal activity at dosages between 1 and 2 mg/kg/d, and these results were superior to fluconazole and similar to amphotericin B treatment. When ATI-2307 was combined with fluconazole, the antifungal effect was greater than either therapy alone. While ATI-2307 has potent anticryptococcal activity in the subarachnoid space, its ability to reduce yeasts in the brain parenchyma was relatively less over the same study period. This new drug, with its unique mechanism of fungicidal action and ability to positively interact with an azole, has demonstrated sufficient anticryptococcal potential in this experimental setting to be further evaluated in clinical studies.

Development and validation of a machine learning model to predict prognosis in HIV-negative cryptococcal meningitis patients: a multicenter study

PURPOSE

To predict prognosis in HIV-negative cryptococcal meningitis (CM) patients by developing and validating a machine learning (ML) model.

METHODS

This study involved 523 HIV-negative CM patients diagnosed between January 1, 1998, and August 31, 2022, by neurologists from 3 tertiary Chinese centers. Prognosis was evaluated at 10 weeks after the initiation of antifungal therapy.

RESULTS

The final prediction model for HIV-negative CM patients comprised 8 variables: Cerebrospinal fluid (CSF) cryptococcal count, CSF white blood cell (WBC), altered mental status, hearing impairment, CSF chloride levels, CSF opening pressure (OP), aspartate aminotransferase levels at admission, and decreased rate of CSF cryptococcal count within 2 weeks after admission. The areas under the curve (AUCs) in the internal, temporal, and external validation sets were 0.87 (95% CI 0.794-0.944), 0.92 (95% CI 0.795-1.000), and 0.86 (95% CI 0.744-0.975), respectively. An artificial intelligence (AI) model was trained to detect and count cryptococci, and the mean average precision (mAP) was 0.993.

CONCLUSION

A ML model for predicting prognosis in HIV-negative CM patients was built and validated, and the model might provide a reference for personalized treatment of HIV-negative CM patients. The change in the CSF cryptococcal count in the early phase of HIV-negative CM treatment can reflect the prognosis of the disease. In addition, utilizing AI to detect and count CSF cryptococci in HIV-negative CM patients can eliminate the interference of human factors in detecting cryptococci in CSF samples and reduce the workload of the examiner.

Reduced Susceptibility to Azoles in Cryptococcus gattii Correlates with the Substitution R258L in a Substrate Recognition Site of the Lanosterol 14-α-Demethylase

Cryptococcus neoformans and Cryptococcus gattii cause cryptococcosis, a life-threatening fungal infection affecting mostly immunocompromised patients. In fact, cryptococcal meningitis accounts for about 19% of AIDS-related deaths in the world. Because of long-term azole therapies to treat this mycosis, resistance to fluconazole leading to treatment failure and poor prognosis has long been reported for both fungal species. Among the mechanisms implicated in resistance to azoles, mutations in the ERG11 gene, encoding the azole target enzyme lanosterol 14-α-demethylase, have been described. This study aimed to establish the amino acid composition of ERG11 of Colombian clinical isolates of C. neoformans and C. gattii and to correlate any possible substitution with the in vitro susceptibility profile of the isolates to fluconazole, voriconazole, and itraconazole. Antifungal susceptibility testing results showed that C. gattii isolates are less susceptible to azoles than C. neoformans isolates, which could correlate with differences in the amino acid composition and structure of ERG11 of each species. In addition, in a C. gattii isolate with high MICs for fluconazole (64 μg/mL) and voriconazole (1 μg/mL), a G973T mutation resulting in the substitution R258L, located in substrate recognition site 3 of ERG11, was identified. This finding suggests the association of the newly reported substitution with the azole resistance phenotype in C. gattii. Further investigations are needed to determine the exact role that R258L plays in the decreased susceptibility to fluconazole and voriconazole, as well as to determine the participation of additional mechanisms of resistance to azole drugs. IMPORTANCE The fungal species Cryptococcus neoformans and C. gattii are human pathogens for which drug resistance or other treatment and management challenges exist. Here, we report differential susceptibility to azoles among both species, with some isolates displaying resistant phenotypes. Azoles are among the most commonly used drugs to treat cryptococcal infections. Our findings underscore the necessity of testing antifungal susceptibility in the clinical setting in order to assist patient management and beneficial outcomes. In addition, we report an amino acid change in the sequence of the target protein of azoles, which suggests that this change might be implicated in resistance to these drugs. Identifying and understanding possible mechanisms that affect drug affinity will eventually aid the design of new drugs that overcome the global growing concern of antifungal resistance.

Toll-like receptor 4 and macrophage scavenger receptor 1 crosstalk regulates phagocytosis of a fungal pathogen

The opportunistic fungal pathogen Cryptococcus neoformans causes lethal infections in immunocompromised patients. Macrophages are central to the host response to cryptococci; however, it is unclear how C. neoformans is recognised and phagocytosed by macrophages. Here we investigate the role of TLR4 in the non-opsonic phagocytosis of C. neoformans. We find that loss of TLR4 function unexpectedly increases phagocytosis of non-opsonised cryptococci by murine and human macrophages. The increased phagocytosis observed in Tlr4-/- cells was dampened by pre-treatment of macrophages with oxidised-LDL, a known ligand of scavenger receptors. The scavenger receptor, macrophage scavenger receptor 1 (MSR1) (also known as SR-A1 or CD204) was upregulated in Tlr4-/- macrophages. Genetic ablation of MSR1 resulted in a 75% decrease in phagocytosis of non-opsonised cryptococci, strongly suggesting that it is a key non-opsonic receptor for this pathogen. We go on to show that MSR1-mediated uptake likely involves the formation of a multimolecular signalling complex involving FcγR leading to SYK, PI3K, p38 and ERK1/2 activation to drive actin remodelling and phagocytosis. Altogether, our data indicate a hitherto unidentified role for TLR4/MSR1 crosstalk in the non-opsonic phagocytosis of C. neoformans.

Comparative analysis of diagnostic methods for the detection of Cryptococcus neoformans meningitis

BACKGROUND

Cryptococcosis is a devastating opportunistic infection in immunocompromised individuals, primarily in people living with HIV/AIDS. This study evaluated a protocol for the early diagnosis of meningitis due to C. neoformans, utilizing established molecular techniques from serum and CSF samples.

METHODS

The 18S and 5.8S (rDNA-ITS) sequence-specific nested PCR assays were compared with direct India ink staining and the latex agglutination test for detection of C. neoformans in serum and cerebrospinal fluid (CSF) from 49 Brazilian suspected meningitis patients. Results were validated with samples obtained from 10 patients negative for cryptococcosis and HIV, and by analysis of standard C. neoformans strains.

PRINCIPAL FINDINGS

The 5.8S DNA-ITS PCR was more sensitive (89-100%) and specific (100%) than the 18S rDNA PCR and conventional tests (India ink staining and latex agglutination) for identification of C. neoformans. While the 18S PCR exhibited a sensitivity (72%) similar to that of the latex agglutination assay in serum samples, it was superior to the latex agglutination assay when testing CSF, with a sensitivity of 84%. However, the latex agglutination was superior to the 18SrDNA PCR in specificity in CSF (92%). The 5.8S DNA-ITS PCR yielded the highest levels of accuracy (96-100%) of any test for detection (serological and mycological) of C. neoformans in both serum and CSF.

CONCLUSION

Use of the nested 5.8S PCR was superior to other techniques for the diagnosis of cryptococcosis. The possibility of using serum, a non-invasively collected material, in a targeted 5.8S PCR analysis to identify Cryptococcus spp. is recommended, especially in immunosuppressed patients. Our results indicate that nested 5.8S PCR can increase the diagnostic capability of cryptococcosis, and we suggest its use to monitor patients in the future.

Trends of CNS Cryptococcosis during Pre- and Post-HIV era: A 38 years' retrospective cohort analysis from south India

OBJECTIVE

Central nervous system cryptococcosis (CNSc) is an AIDS defining opportunistic infection. This retrospective study aimed to analyze the changing epidemiology of CNSc cases from the period of pre- to post-emergence of HIV epidemic in south India.

METHODS

Confirmed cases of CNSc from 1978 to 2015 were analyzed for demographic and clinical details with special reference to the cases diagnosed in south India during the period 1952-1977. Geographical distribution, affected age groups, clinical aspects, and comorbidities in relation to immune status were analysed RESULTS: The highest number of CNSc cases (n = 125) were recorded in 2006, with 89.6% HIV positivity. The highest HIV-positivity (93.6%) was documented in the years 2002 and 2009. CNSc cases have majorly changed after the introduction and spread of HIV in terms of predisposing factors, comorbidities, severity, affected age groups and treatment. Notably, an overall rise was observed in non-HIV associated CNSc cases from 1997 (8.1%) to 2015 (16.9%).

CONCLUSION

The peak of CNSc had already reached in south India during 2005-2006. However, the number of new infections has slowly decreased in last ten years. Progressive awareness and, early diagnosis of HIV and cryptococcosis, adequate availability of HAART and potential antifungal therapy has played crucial roles in changing epidemiology of the CNSc and its associated mortality.

Cryptococcus neoformans Causing Meningoencephalitis in Adults and a Child from Lima, Peru: Genotypic Diversity and Antifungal Susceptibility

Cryptococcosis, caused predominantly by Cryptococcus neoformans, is a potentially fatal, opportunistic infection that commonly affects the central nervous system of immunocompromised patients. Globally, this mycosis is responsible for almost 20% of AIDS-related deaths, and in countries like Peru, its incidence remains high, mostly due to the annual increase in new cases of HIV infection. This study aimed to establish the genotypic diversity and antifungal susceptibility of C. neoformans isolates causing meningoencephalitis in 25 adults and a 9-year-old girl with HIV and other risk factors from Lima, Peru. To identify the genotype of the isolates, multilocus sequence typing was applied, and to establish the susceptibility of the isolates to six antifungals, a YeastOne® broth microdilution was used. From the isolates, 19 were identified as molecular type VNI, and seven as VNII, grouped in eight and three sequence types, respectively, which shows that the studied population was highly diverse. Most isolates were susceptible to all antifungals tested. However, VNI isolates were less susceptible to fluconazole, itraconazole and voriconazole than VNII isolates (p < 0.05). This study contributes data on the molecular epidemiology and the antifungal susceptibility profile of the most common etiological agent of cryptococcosis, highlighting a pediatric case, something which is rare among cryptococcal infection.

Cryptococcal Immune Reconstitution Inflammatory Syndrome: From Clinical Studies to Animal Experiments

Cryptococcus neoformans is an encapsulated pathogenic fungus that initially infects the lung but can migrate to the central nervous system (CNS), resulting in meningoencephalitis. The organism causes the CNS infection primarily in immunocompromised individuals including HIV/AIDS patients, but also, rarely, in immunocompetent individuals. In HIV/AIDS patients, limited inflammation in the CNS, due to impaired cellular immunity, cannot efficiently clear a C. neoformans infection. Antiretroviral therapy (ART) can rapidly restore cellular immunity in HIV/AIDS patients. Paradoxically, ART induces an exaggerated inflammatory response, termed immune reconstitution inflammatory syndrome (IRIS), in some HIV/AIDS patients co-infected with C. neoformans. A similar excessive inflammation, referred to as post-infectious inflammatory response syndrome (PIIRS), is also frequently seen in previously healthy individuals suffering from cryptococcal meningoencephalitis. Cryptococcal IRIS and PIIRS are life-threatening complications that kill up to one-third of affected people. In this review, we summarize the inflammatory responses in the CNS during HIV-associated cryptococcal meningoencephalitis. We overview the current understanding of cryptococcal IRIS developed in HIV/AIDS patients and cryptococcal PIIRS occurring in HIV-uninfected individuals. We also describe currently available animal models that closely mimic aspects of cryptococcal IRIS observed in HIV/AIDS patients.

Antifungal susceptibility and molecular characteristics of Cryptococcus spp. based on whole-genome sequencing in Zhejiang Province, China

Cryptococcus spp. is a complex species that often causes cryptococcosis, which is one of the most common opportunistic infections in adults living with HIV and has very high morbidity and mortality rates. This study aimed to investigate the antifungal susceptibility profiles and epidemiological characteristics of the Cryptococcus neoformans species complex (CNSC) and the Cryptococcus gattii species complex (CGSC) in Zhejiang Province, China. A total of 177 CNSC and 3 CGSC isolates were collected, and antifungal susceptibility was tested by FUNGUS 3 and verified with an E-test. Moreover, multiple classification methods and genomic analyses were performed. The majority of the isolates (96.11%) were C. neoformans (formerly C. neoformans var. grubii) (ST5-VNI-A-α). Our study highlights that most of the patients with cryptococcosis were non-HIV patients in China, and nearly half of them did not have underlying diseases that led to immune insufficiency. Most of the Cryptococcus spp. isolates in this study were sensitive to common antifungal drugs. Two 5-flucytosine (5-FC)-resistant strains were identified, and FUR1 mutation was detected in the 5-FC-resistant isolates. Typing based on whole-genome sequencing (WGS) showed better discrimination than that achieved with multilocus sequence typing (MLST) and indicated a clear population structure. A phylogenetic analysis based on WGS included more genomic information than traditional classification methods.

Analyses of the Global Multilocus Genotypes of the Human Pathogenic Yeast Cryptococcus neoformans Species Complex

Cryptococcus neoformans species complex (CNSC) is a globally distributed human opportunistic yeast pathogen consisting of five major molecular types (VNI, VNII, VNB, VNIII and VNIV) belonging to two species, C. neoformans (VNI, VNII and VNB, collectively called serotype A) and C. deneoformans (VNIV, commonly called serotype D), and their hybrids (VNIII, serotype AD). Over the years, many studies have analyzed the geographical distribution and genetic diversity of CNSC. However, the global population structure and mode of reproduction remain incompletely described. In this study, we analyze the published multilocus sequence data at seven loci for CNSC. The combined sequences at the seven loci identified a total of 657 multilocus sequence types (STs), including 296 STs with known geographic information, representing 4200 non-redundant isolates from 31 countries and four continents. Among the 296 STs, 78 and 52 were shared among countries and continents, respectively, representing 3643 of the 4200 isolates. Except for the clone-corrected serotype D sample among countries, our analysis of the molecular variance of the 4200 isolates revealed significant genetic differentiations among countries and continents in populations of CNSC, serotype A, and serotype D. Phylogenetic analyses of the concatenated sequences of all 657 STs revealed several large clusters corresponding to the major molecular types. However, several rare but distinct STs were also found, representing potentially novel molecular types and/or hybrids of existing molecular types. Phylogenetic incompatibility analyses revealed evidence for recombination within all four major molecular types-VNI, VNII, VNIV and VNB-as well as within two VNB subclades, VNBI and VNBII, and two ST clusters around the most common STs, ST5 and ST93. However, linkage disequilibrium analyses rejected the hypothesis of random recombination across most samples. Together, our results suggest evidence for historical differentiation, frequent recent gene flow, clonal expansion and recombination within and between lineages of the global CNSC population.

Diffuse Adrenal Gland and Pancreas Necrosis in a Patient with Disseminated Cryptococcosis-Case Report

(1) Background: Cryptococcus neoformans is mostly known for causing meningitis, with or without disseminated disease. (2) Case presentation: An immunocompromised 75-year-old gentleman presented post renal transplant with generalized weakness, altered mental status, hypoxemia, and hyponatremia, and was found to have disseminated cryptococcal infection. After an initial improvement, the patient became suddenly hypotensive, and passed away soon after. The autopsy revealed widespread cryptococcal involvement, with the most severely affected organs being the brain, lungs, pancreas, adrenal glands, and spleen. The pancreas and one of the adrenal glands revealed diffuse granulomatous cryptococcal infection, with large areas of necrosis. The spleen also showed a large area of cryptococcal necrosis. In addition, the patient had chylous ascites, without histologically identifiable organisms. (3) Conclusions: This is a rare case of disseminated cryptococcal infection with severe necrotizing adrenalitis and pancreatitis, in addition to significant spleen, lung, and central nervous system involvement. The early recognition and treatment of the adrenal gland and pancreas cryptococcosis with surgical interventions may lead to better outcomes in affected patients. Furthermore, steroid treatment and diabetes mellitus may be risk factors for adrenal gland involvement. Additionally, clinicians should keep cryptococcal infection in their differential diagnosis for isolated adrenal gland and pancreas lesions.

Cryptococcus neoformans Infection in the Central Nervous System: The Battle between Host and Pathogen

Cryptococcus neoformans (C. neoformans) is a pathogenic fungus with a global distribution. Humans become infected by inhaling the fungus from the environment, and the fungus initially colonizes the lungs. If the immune system fails to contain C. neoformans in the lungs, the fungus can disseminate to the blood and invade the central nervous system, resulting in fatal meningoencephalitis particularly in immunocompromised individuals including HIV/AIDS patients. Following brain invasion, C. neoformans will encounter host defenses involving resident as well as recruited immune cells in the brain. To overcome host defenses, C. neoformans possesses multiple virulence factors capable of modulating immune responses. The outcome of the interactions between the host and C. neoformans will determine the disease progression. In this review, we describe the current understanding of how C. neoformans migrates to the brain across the blood–brain barrier, and how the host immune system responds to the invading organism in the brain. We will also discuss the virulence factors that C. neoformans uses to modulate host immune responses.

Capsule-Deficient Cryptococcal Meningitis: A Diagnostic Conundrum

Cryptococcosis is a serious systemic mycosis. Its incidence has escalated in the past four decades. Cryptococcus neoformans causes localized or disseminated infection in immunocompromised and immunocompetent patients. The capsulated form is commonly encountered which can be diagnosed on an India ink preparation or antigen detection. However, the noncapsulated forms are very rare and require a high index of suspicion for correct diagnosis. Herein, we present a case of cryptococcal meningitis due to a noncapsulated strain in an apparently immunocompetent patient with no proven immunodeficiencies along with review of world literature. Such cases are a diagnostic challenge for the clinician as well as microbiologist.

Immunologic Diagnosis of Endemic Mycoses

The endemic mycoses blastomycosis, coccidioidomycosis, histoplasmosis, paracoccidioidomycosis, cryptococcosis, sporotrichosis, talaromycosis, adiaspiromycosis, and emergomycosis are mostly caused by geographically limited thermally dimorphic fungi (except for cryptococcosis), and their diagnoses can be challenging. Usual laboratory methods involved in endemic mycoses diagnosis include microscopic examination and culture of biological samples; however, serologic, histopathologic, and molecular techniques have been implemented in the last few years for the diagnosis of these mycoses since the recovery and identification of their etiologic agents is time-consuming and lacks in sensitivity. In this review, we focus on the immunologic diagnostic methods related to antibody and antigen detection since their evidence is presumptive diagnosis, and in some mycoses, such as cryptococcosis, it is definitive diagnosis.

Neuromeningeal cryptococcosis in a patient not infected with human immunodeficiency virus and without known risk factors: A case report

We report a 24-year-old female patient not infected with human immunodeficiency virus (HIV) and without other risk factors of immunosuppression, presenting with neuromeningeal cryptococcosis. Cerebrospinal fluid (CSF) analysis revealed the presence of Cryptococcus neoformans. The evolution was unfavorable and the patient died even after appropriate antifungal treatment.

Hemolymph of triatomines presents fungistatic activity against Cryptococcus neoformans and improves macrophage function through MCP-I/TNF-α increase

BACKGROUND

Triatomines are blood-feeding arthropods belonging to the subfamily Triatominae (Hemiptera; Reduviidae), capable of producing immunomodulatory and water-soluble molecules in their hemolymph, such as antimicrobial peptides (AMPs). In this work, we evaluated the antifungal and immunomodulatory activity of the hemolymph of Meccus pallidipennis (MPH) and Rhodnius prolixus (RPH) against Cryptococcus neoformans.

METHODS

We assessed the activity of the hemolymph of both insects on fungal growth by a minimum inhibitory concentration (MIC) assay. Further, RAW 264.7 macrophages were cultivated with hemolymph and challenged with C. neoformans. Then, their phagocytic and killing activities were assessed. The cytokines MCP-1, IFN-γ, TNF-α, IL-10, IL-12, and IL-6 were measured in culture supernatants 4- and 48-hours post-infection.

RESULTS

Both hemolymph samples directly affected the growth rate of the fungus in a dose-dependent manner. Either MPH or RPH was capable of inhibiting fungal growth by at least 70%, using the lowest dilution (1:20). Treatment of RAW 264.7 macrophages with hemolymph of both insects was capable of increasing the production of MCP-I and TNF-α. In addition, when these cells were stimulated with hemolymph in the presence of C. neoformans, a 2- and a 4-fold increase in phagocytic rate was observed with MPH and RPH, respectively, when compared to untreated cells. For the macrophage killing activity, MPH decreased in approximately 30% the number of viable yeasts inside the cells compared to untreated control; however, treatment with RPH could not reduce the total number of viable yeasts. MPH was also capable of increasing MHC-II expression on macrophages. Regarding the cytokine production, MCP-I and TNF-α, were increased in the supernatant of macrophages treated with both hemolymphs, 4 and 48 hours after stimulation.

CONCLUSION

These results suggested that hemolymph of triatomines may represent a source of molecules capable of presenting antifungal and immunomodulatory activity in macrophages during fungal infection.

Cryptococcus neoformans Genotypic Diversity and Disease Outcome among HIV Patients in Africa

Cryptococcal meningoencephalitis, a disease with poor patient outcomes, remains the most prevalent invasive fungal infection worldwide, accounting for approximately 180,000 deaths each year. In several areas of sub-Saharan Africa with the highest HIV prevalence, cryptococcal meningitis is the leading cause of community-acquired meningitis, with a high mortality among HIV-infected individuals. Recent studies show that patient disease outcomes are impacted by the genetics of the infecting isolate. Yet, there is still limited knowledge of how these genotypic variations contribute to clinical disease outcome. Further, it is unclear how the genetic heterogeneity of C. neoformans and the extensive phenotypic variation observed between and within isolates affects infection and disease. In this review, we discuss current knowledge of how various genotypes impact disease progression and patient outcome in HIV-positive populations in sub-Saharan African, a setting with a high burden of cryptococcosis.

Cryptococcus: History, Epidemiology and Immune Evasion

Cryptococcosis is a disease caused by the pathogenic fungi Cryptococcus neoformans and Cryptococcus gattii, both environmental fungi that cause severe pneumonia and may even lead to cryptococcal meningoencephalitis. Although C. neoformans affects more fragile individuals, such as immunocompromised hosts through opportunistic infections, C. gattii causes a serious indiscriminate primary infection in immunocompetent individuals. Typically seen in tropical and subtropical environments, C. gattii has increased its endemic area over recent years, largely due to climatic factors that favor contagion in warmer climates. It is important to point out that not only C. gattii, but the Cryptococcus species complex produces a polysaccharidic capsule with immunomodulatory properties, enabling the pathogenic species of Cryptococccus to subvert the host immune response during the establishment of cryptococcosis, facilitating its dissemination in the infected organism. C. gattii causes a more severe and difficult-to-treat infection, with few antifungals eliciting an effective response during chronic treatment. Much of the immunopathology of this cryptococcosis is still poorly understood, with most studies focusing on cryptococcosis caused by the species C. neoformans. C. gattii became more important in the epidemiological scenario with the outbreaks in the Pacific Northwest of the United States, which resulted in phylogenetic studies of the virulent variant responsible for the severe infection in the region. Since then, the study of cryptococcosis caused by C. gattii has helped researchers understand the immunopathological aspects of different variants of this pathogen.

Establishing Minimal Conditions Sufficient for the Development of Titan-like Cells in Cryptococcus neoformans/gattii Species Complex

Opportunistic pathogens of the anamorphic genus Cryptococcus are unique considering their virulence factors that in the context of pathogenesis allowed them to achieve evolutionary success. Morphological transformation into giant (Titan) cells is one of the factors contributing to cryptococcosis. Recently established in vitro protocols demonstrate that 5 or 10% fetal bovine serum (FBS) combined with 5% CO2, 37 °C, and sufficiently low cell density, triggers cellular enlargement (Serum protocols). However, the FBS components that promote this morphological transition remain incompletely characterized. In search of minimal conditions necessary for stimulating the formation of Titan cells, we performed a study where we eliminated serum from the protocol (Serum-free protocol) and instead systematically adjusted the amount of glucose, source of nitrogen (ammonium sulfate), and the pH. We found that exposing cells to PBS with adjusted pH to 7.3, and supplemented with 0.05% glucose, 0.025% ammonium sulfate, 0.004% K2HPO4, 0.0035% MgSO4, in the presence of 5% CO2 at 37 °C triggers Titan-like cell formation to the same degree as the previously established protocol that utilized 10% FBS as the sole nutrient source. Titan-like cells obtained according to this Serum-free protocol were characterized by cell body size over ten microns, a single enlarged vacuole, thick cell wall, extensive polysaccharide capsule, and changes in the level of cell ploidy, all currently known hallmarks of Titan cells found in vivo. Strikingly, we found that in both, Serum and Serum-free protocols, an optimal pH for Titan-like cell development is ~7.3 whereas relatively acidic pH (5.5) prevents this morphological transition and promotes robust proliferation, while alkaline pH (~8.0) has a profound growth inhibitory effect. Our study demonstrates a critical role of pH response to the formation of Titan cells and indicates that conditions that allow restricted proliferation in the presence of 5% CO2 are sufficient for this morphological transition to form enlarged cells in Cryptococcus neoformans and Cryptococcus gattii species complex.

Patel A, Patel D N, B. Sharath D, Mansouri B, Contreras C. Cutaneous cryptococcal infection: Initial manifestation of acquired T-cell immunodeficiency due to malignant thymoma

Background and Purpose

Cryptococcosis is a known opportunistic infection. Thymomas are known to cause immune dysregulation. We describe an atypical case of cutaneous cryptococcosis in a patient with acquired T cell immunodeficiency that has been found to be secondary to a type B3 thymoma with progression to carcinoma.

Case report

A 63-year-old male presented with a chronic skin lesion confirmed as Cryptococcus neoformans on biopsy and an incidental mediastinal mass found during infectious work-up for the notable cluster of differentiation 4 (CD4)+ lymphopenia. This led to the diagnosis of a type B3 thymoma requiring resection. The cryptococcal lesion was treated successfully with azole therapy.

Conclusion

C. neoformans is an opportunistic infection rarely associated with isolated T cell immunodeficiency due to thymomas. A multidisciplinary approach and understanding of the pathogenicity of cryptococcus and the immunological effect of thymic dysfunction are paramount to diagnosis and treatment.

A Fatal Fungal Infection of Cryptococcus gattii (VGI) Meningitis in Texas

Cryptococcus gattii is an under-recognized cause of meningitis, especially in non-endemic regions. This report details C. gattii disease progression from admission to autopsy in an otherwise healthy 40-year-old male in Texas. It brings awareness to an often unsuspected organism that can cause severe infection requiring early recognition and treatment in immunocompetent individuals.

More Than Just Cleaning: Ubiquitin-Mediated Proteolysis in Fungal Pathogenesis

Ubiquitin-proteasome mediated protein turnover is an important regulatory mechanism of cellular function in eukaryotes. Extensive studies have linked the ubiquitin-proteasome system (UPS) to human diseases, and an array of proteasome inhibitors have been successfully developed for cancer therapy. Although still an emerging field, research on UPS regulation of fungal development and virulence has been rapidly advancing and has generated considerable excitement in its potential as a target for novel drugs. In this review, we summarize UPS composition and regulatory function in pathogenic fungi, especially in stress responses, host adaption, and fungal pathogenesis. Emphasis will be given to UPS regulation of pathogenic factors that are important for fungal pathogenesis. We also discuss future potential therapeutic strategies for fungal infections based on targeting UPS pathways.

Phenotypic Plasticity in the Productions of Virulence Factors Within and Among Serotypes in the Cryptococcus neoformans Species Complex

The Cryptococcus neoformans species complex (CNSC) is a common opportunistic human fungal pathogen and the most frequent cause of fungal meningitis. There are three major serotypes in CNSC: A, D, and their hybrids AD, and they have different geographic distributions and medical significance. Melanin pigment and a polysaccharide capsule are the two major virulence factors in CNSC. However, the relationships between serotype and virulence factor production and how environmental factors might impact their relationships are not known. This study investigated the expressions of melanin and capsular polysaccharide in a genetically diverse group of CNSC strains and how their phenotypic expressions were influenced by oxidative and nitrosative stress levels. We found significant differences in melanin and capsular polysaccharide productions among serotypes and across stress conditions. Under oxidative stress, the laboratory hybrids exhibited the highest phenotypic plasticity for melanin production while serotype A showed the highest for capsular polysaccharide production. In contrast, serotype D exhibited the highest phenotypic plasticity for capsular polysaccharide production and clinical serotype AD the highest phenotypic plasticity for melanin production under nitrosative stress. These results demonstrated that different serotypes have different environmental condition-specific mechanisms to modulate the expression of virulence factors.

Epitope-Based Immunoinformatic Approach on Heat Shock 70 kDa Protein Complex of Cryptococcus neoformans var. grubii

INTRODUCTION

Cryptococcosis is a ubiquitous opportunistic fungal disease caused by Cryptococcus neoformans var. grubii. It has high global morbidity and mortality among HIV patients and non-HIV carriers with 99% and 95%, respectively. Furthermore, the increasing prevalence of undesired toxicity profile of antifungal, multidrug-resistant organisms and the scarcity of FDA-authorized vaccines were the hallmark in the present days. This study was undertaken to design a reliable epitope-based peptide vaccine through targeting highly conserved immunodominant heat shock 70 kDa protein of Cryptococcus neoformans var. grubii that covers a considerable digit of the world population through implementing a computational vaccinology approach.

MATERIALS AND METHODS

A total of 38 sequences of Cryptococcus neoformans var. grubii's heat shock 70 kDa protein were retrieved from the NCBI protein database. Different prediction tools were used to analyze the aforementioned protein at the Immune Epitope Database (IEDB) to discriminate the most promising T-cell and B-cell epitopes. The proposed T-cell epitopes were subjected to the population coverage analysis tool to compute the global population's coverage. Finally, the T-cell projected epitopes were ranked based on their binding scores and modes using AutoDock Vina software. Results and Discussion. The epitopes (ANYVQASEK, QSEKPKNVNPVI, SEKPKNVNPVI, and EKPKNVNPVI) had shown very strong binding affinity and immunogenic properties to B-cell. (FTQLVAAYL, YVYDTRGKL) and (FFGGKVLNF, FINAQLVDV, and FDYALVQHF) exhibited a very strong binding affinity to MHC-I and MHC-II, respectively, with high population coverage for each, while FYRQGAFEL has shown promising results in terms of its binding profile to MHC-II and MHC-I alleles and good strength of binding when docked with HLA-C∗12:03. In addition, there is massive global population coverage in the three coverage modes. Accordingly, our in silico vaccine is expected to be the future epitope-based peptide vaccine against Cryptococcus neoformans var. grubii that covers a significant figure of the entire world citizens.

A Fragile Balance: Does Neutrophil Extracellular Trap Formation Drive Pulmonary Disease Progression?

Neutrophils act as the first line of defense during infection and inflammation. Once activated, they are able to fulfil numerous tasks to fight inflammatory insults while keeping a balanced immune response. Besides well-known functions, such as phagocytosis and degranulation, neutrophils are also able to release "neutrophil extracellular traps" (NETs). In response to most stimuli, the neutrophils release decondensed chromatin in a NADPH oxidase-dependent manner decorated with histones and granule proteins, such as neutrophil elastase, myeloperoxidase, and cathelicidins. Although primarily supposed to prevent microbial dissemination and fight infections, there is increasing evidence that an overwhelming NET response correlates with poor outcome in many diseases. Lung-related diseases especially, such as bacterial pneumonia, cystic fibrosis, chronic obstructive pulmonary disease, aspergillosis, influenza, and COVID-19, are often affected by massive NET formation. Highly vascularized areas as in the lung are susceptible to immunothrombotic events promoted by chromatin fibers. Keeping this fragile equilibrium seems to be the key for an appropriate immune response. Therapies targeting dysregulated NET formation might positively influence many disease progressions. This review highlights recent findings on the pathophysiological influence of NET formation in different bacterial, viral, and non-infectious lung diseases and summarizes medical treatment strategies.

Titan cell formation is unique to Cryptococcus species complex

Members of the Cryptococcus species complex stand out by unique virulence factors that allowed evolutionary transition to pathogenesis. Among the factors contributing to cryptococcosis is a morphological transformation into giant (Titan) cells. It remains unclear whether species outside of the C. neoformans/C. gattii species complex are capable of titanization. We utilized two recently developed protocols that allow obtaining Titan cells in vitro to test if titanization occurs in non-C. neoformans/C. gattii species. We find that none of the tested strains, representing 10 species of basidiomycetous yeasts and the ascomycetous yeast Saccharomyces cerevisiae, undergo significant titanization under conditions that promote robust Titan cell formation in C. neoformans/C. gattii species complex. C. terreus formed occasional enlarged cells through a mechanism potentially similar to that of titanization. Our findings suggest that titanization is a rare phenomenon among basidiomycetous yeasts that occurs mostly in members of the C. neoformans/C. gattii species complex.

A 34-Year-Old Man With HIV/AIDS and a Cavitary Pulmonary Lesion

A 34-year-old man presented to a community hospital with fever and fatigue for 3 days and was found to be febrile and tachycardic with a cavitary pulmonary lesion and paratracheal adenopathy on CT imaging. One month before, he had presented to his primary care provider with a palmar rash; he had been diagnosed and treated for syphilis and was also diagnosed with HIV. He had a CD4 count of 106 cells/μL and an HIV viral load of 1,290,000 copies/mL. Pneumocystis prophylaxis with trimethoprim-sulfamethoxazole and antiretroviral treatment with only tenofovir and emtricitabine therapy were started 2 weeks before presentation.

Cryptococcosis

Cryptococcosis is an invasive fungal infection of global significance caused by yeasts of the genus Cryptococcus. The prevalence of HIV in certain areas of the world and the expanding population of immunocompromised patients contribute to the ongoing global disease burden. Point-of-care serologic testing has allowed for more rapid diagnosis and implementation of screening programs in resource-limited settings. Management involves therapy aimed at reduction in fungal burden, maintenance of intracranial pressure, and optimization of host immunity. Despite diagnostic and therapeutic advances, cryptococcosis continues to be a disease with unacceptably high incidence and mortality, particularly in resource-limited settings.

Initial diagnosis of HIV/AIDS in patients presenting to the emergency department: Imaging and clinical findings at a single institution

PURPOSE

To evaluate the clinical, laboratory, and imaging findings along with treatment and outcomes associated with patients presenting to the emergency department (ED) who were subsequently diagnosed with HIV/AIDS.

METHODS

591 patients with HIV and available imaging studies presenting to our hospital's ED between 2004 and 2019 were identified in the medical record. Following initial review, we identified 19 patients who were diagnosed with HIV within one week after an initial ED visit and also had received CT imaging during the ED visit. Demographic, clinical, treatment, imaging, and outcome data were reviewed and recorded for each patient.

RESULTS

Among this 19-patient cohort, the most common indication for HIV testing was oral/esophageal candidiasis (n = 8, 42%). 12 patients presented with an AIDS-defining illness upon initial diagnosis; the most common were esophageal candidiasis (4) and Pneumocystis jiroveci pneumonia (PJP) (3). 10 patients (59%) presented with CD4+ counts <200 cells/L. The most common imaging findings were liver abnormalities (n = 9, 47%). Five of the 19 patients were confirmed deceased at the time of this study, with the median time from diagnosis to death of 5.6 months (range 8 days-14 months).

CONCLUSION

Our series demonstrates the breadth of potential imaging findings and clinical presentations of late-stage HIV in the emergency setting, including common AIDS-defining illnesses such as PJP and PML. Although the incidence of these conditions is decreasing, maintaining awareness of their clinical and imaging findings, as well as the potential for multi-organ involvement, is essential due to the possibility of rapid decline in these patients.

Clinical characteristics and evaluation of the incidence of cryptococcosis in Finland 2004-2018

BACKGROUND

Cryptococcosis is one of the major causes of mortality among HIV patients worldwide. Though most often associated with late stage HIV infection/AIDS, a significant number of cases occur in other immunocompromised patients such as solid organ transplant recipients and patients with hematological malignancies. Immunocompromised patients are a heterogeneous group and their number increases constantly. Since little is known about the incidence and the clinical features of cryptococcosis in Northern Europe, our aim was to investigate the clinical characteristics of cryptococcosis patients in Finland.

METHODS

We retrospectively reviewed the laboratory confirmed cryptococcosis cases in Finland during 2004-2018. Only those who were treated for cryptococcosis were included in the study. Initial laboratory findings and medical records were also collected.

RESULTS

A total of 22 patients with cryptococcosis were included in our study. The annual incidence of cryptococcosis was 0.03 cases per 100,000 population. Ten patients were HIV-positive and 12 out of 22 were HIV-negative. Hematological malignancy was the most common underlying condition among HIV-negative patients.

CONCLUSIONS

To our knowledge, this is the first study of the clinical presentation and incidence of cryptococcosis in Finland. We demonstrate that invasive cryptococcal infection occurs not only in HIV/AIDS patients or otherwise immunocompromised patients but also in immunocompetent individuals. Even though cryptococcosis is extremely rare in Finland, its recognition is important since the prognosis depends on rapid diagnostics and early antifungal therapy.

Clinicopathological features of isolated pulmonary cryptococcosis in HIV-negative patients

Objective

To analyse the clinicopathological features of isolated pulmonary cryptococcosis in human immunodeficiency virus (HIV)-negative patients.

Methods

This retrospective study analysed the following data from HIV-negative patients diagnosed with pulmonary cryptococcosis: demographics, underlying diseases, clinical manifestations on admission, laboratory tests, imaging data, results of histopathology, treatment options and outcomes. Sputum samples from all patients were collected and assessed for the presence of yeast or fungi. Cryptococcal antigen testing was performed for some patients. Histopathological analysis was also undertaken for some samples of lung tissue.

Results

The study analysed 37 patients (22 males). Thirteen (35.14%) patients were asymptomatic, 24 (64.86%) were symptomatic and 17 (45.95%) patients had no underlying disease. Out of 25 tested patients, 23 (92.00%) tested positive on the serum cryptococcal capsular polysaccharide antigen test. During 6 to 24 months of follow-up, all 37 patients that were either treated with or without antifungal therapy alone or combined with surgical resection showed complete recovery. One patient made a full recovery without any treatment.

Conclusion

Early identification of pulmonary cryptococcosis in HIV-negative patients and timely detection of cryptococcal antigens in serum or respiratory specimens may help to improve diagnosis, prognosis and treatment of the disease.

Ibrexafungerp: A First-in-Class Oral Triterpenoid Glucan Synthase Inhibitor

Ibrexafungerp (formerly SCY-078 or MK-3118) is a first-in-class triterpenoid antifungal or “fungerp” that inhibits biosynthesis of β-(1,3)-D-glucan in the fungal cell wall, a mechanism of action similar to that of echinocandins. Distinguishing characteristics of ibrexafungerp include oral bioavailability, a favourable safety profile, few drug–drug interactions, good tissue penetration, increased activity at low pH and activity against multi-drug resistant isolates including C. auris and C. glabrata. In vitro data has demonstrated broad and potent activity against Candida and Aspergillus species. Importantly, ibrexafungerp also has potent activity against azole-resistant isolates, including biofilm-forming Candida spp., and echinocandin-resistant isolates. It also has activity against the asci form of Pneumocystis spp., and other pathogenic fungi including some non-Candida yeasts and non-Aspergillus moulds. In vivo data have shown IBX to be effective for treatment of candidiasis and aspergillosis. Ibrexafungerp is effective for the treatment of acute vulvovaginal candidiasis in completed phase 3 clinical trials.