Central nervous system candidiasis in the high-risk neonate

A novel inherited CARD9 deficiency in an otherwise healthy woman with CNS candidiasis

Patients with caspase-associated recruitment domain-9 (CARD9) deficiency are more likely to develop invasive fungal disease that affect CNS. However, the understanding of how Candida invades and persists in CNS is still limited. We here reported a 24-year-old woman who were previously immunocompetent and diagnosed with CNS candidiasis. A novel autosomal recessive homozygous CARD9 mutation (c.184 + 5G > T) from this patient was identified using whole genomic sequencing. Furthermore, we extensively characterized the impact of this CARD9 mutation on the host immune response in monocytes, neutrophils and CD4 + T cells, using single cell sequencing and in vitro experiments. Decreased pro-inflammatory cytokine productions of CD14 + monocyte, impaired Th17 cell differentiation, and defective neutrophil accumulation in CNS were found in this patient. In conclusion, this study proposed a novel mechanism of CNS candidiasis development. Patients with CNS candidiasis in absence of known immunodeficiencies should be analyzed for CARD9 gene mutation as the cause of invasive fungal infection predisposition.

Candida albicans causes brain regional invasion and necrosis, and activation of microglia during lethal neonatal neurocandidiasis

Neurocandidiasis is a fungal infection that primarily affects neonates, which is associated with 70% case fatality rates, while pediatric patients who survive infection often have long-term neurological sequelae, making it a clinical requirement to understand the pathogenesis of neonatal neurocandidiasis. Currently, the brain regions to Candida albicans invasion during the neonatal period are not characterized. In this study, 0-day-old mice were infected with C. albicans intravenously to determine dissemination and invasion into the brain at different times post-infection by fungal burden assay and histopathological analysis, additionally cellular death and microglial activation were evaluated by flow cytometry. The results evidenced the dissemination of C. albicans within the first hour of infection in the brain. The meninges were the initial site of invasion during the first 6 hours post infection and then filamentous structures into the brain parenchyma increases during infection, the anatomic regions most susceptible to invasion being the cerebral cortex, thalamus, hypothalamus, midbrain, pons, and medulla oblongata. Furthermore, C. albicans invasion of brain tissue results in cell necrosis and activation of microglia as a consequence of fungal invasion.

Clinical characteristics of central nervous system candidiasis due to Candida albicans in children: a single-center experience

BACKGROUND

Central nervous system candidiasis due to Candida albicans (CNSC) in children is easily misdiagnosed and is associated with poor outcomes and a high mortality rate. There is no big data research or systematic review of CNSC.

METHODS

Patients diagnosed as CNSC with positive culture results of Candida albicans in Beijing Children's Hospital affiliated to Capital Medical University from March 2010 to March 2019 were included. Patients receiving immunosuppressive therapy or transplantation, or with malignant tumours were excluded. We analysed the clinical characteristics, follow-up results, drug susceptibility tests and whole-exome sequencing (WES) results.

RESULTS

Thirty-three definitive patients were enrolled, including 22 males and 11 females. Twenty-five patients suffered from CNSC when they were less than 1 year old, and a total of 29 patients had high-risk factors. The main clinical manifestations were fever, convulsions, and positive neurological signs. Twenty-two patients had CNS infections alone, and 11 patients had CNS infections combined with invasive infections involving multiple sites. Twenty-seven cases had a positive CSF and/or blood culture at our hospital. All strains were susceptible to fluconazole, and 2 strains had intermediate susceptibility to voriconazole. As for amphotericin B, all the strains were wild type (WT). WES of 16 patients revealed 2 cases with CARD9 mutations, who suffered from recurrent onychomycosis or thrush before.

CONCLUSION

CNSC mostly existed in children younger than 1 year old, who all had underlying risk factors. CNSC patients with onset at an older age or with recurrent superficial fungal infections might have primary immunodeficiency.

Antimicrobial activity and acetylcholinestrase inhibition of novel synthesized pyrimidine derivatives versus Candida albicans trafficking to brain and kidney

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The current study interested by treatment of Candida albicans in case of invading the fungi into brain and kidney.

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Investigating novel synthesized compounds as antifungal agents then determining their efficiency and safety margin.

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Assessment molecular biochemical parameters specific for inflammation.

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Comparing their antifungal effect to Diflucan in case of invading the fungi to kidney and brain tissue.

The expedient fungi Candida albicans (C. albicans) is able to thrive in many host niches including blood stream, skin, mucosal surfaces, and different body organs. Herein, the assessment of novel synthesized pyrimidine derivatives as anti fungal agent was investigated. Female albino mice were injected intraperitoneally by C. albicans (1.5 × 10⁶ CFU). infected Mice then subjected to treatment with two different doses which was low (50 mg/kg) and high one (200 mg/kg) of diflucan in addition to the newly synthestic compounds (2-(4- (Pyridine- 2- yl) aminosulfonyle phenylamino) - 6 -(naphthalene-2- yl)-4-(pyridine-2- yl) n - 3 carbonitril) and (2-(4-(Pyrimidine-2- yl) aminosulfonyle phenylamino)- 6 -(naphthalene-2- yl)- 4 -(pyridine-2- yl) pyridine-3- carbonitril) donated as (C1 & C2, respectively). Three weeks later gene expression of renal alpha smooth muscle actin (α-SMA) and of cyclooxygenase-2 (COX-2) protein expression were assessed as well as serum malondialdehyde (MDA) and total antioxidant capacity in both kidney and brain tissues. Furthermore, acetylcholinestrase activity was assessed. Candida albicans significantly elevated serum MDA. On the other hand, C. albicans injection revealed a significantly reduction in total antioxidant capacity in kidney as well as in brain tissue. Furthermore, acetylcholine assessment declared a significant elevation. All biochemical parametersۥ upset were modulated upon new synthesized compounds treatment. Molecular analyses declared a significant down - regulation in renal α -smooth muscle actin gene expression in addition to, a significant down- regulation in COX-2 protein expression. From data recorded, it could be concluded that, C2 in a dose 200 mg ∕kg noticeably declared a significant effect comparing with the other treated groups revealing its promising effect as anti-fungal agent.

Differential Behavior of Non-albicans Candida Species in the Central Nervous System of Immunocompetent and Immunosuppressed Mice

The genus Candida includes commensal fungi that can cause local and systemic infections, frequently involving vital organs as the central nervous system (CNS). Candida spp. occupy the fourth place among infections that affect the CNS. Although the incidence of Candida albicans is decreasing among patients under immunosuppressive therapies, the incidence of non-albicans Candida is increasing. In this context, the objective of this work was to evaluate the ability of non-albicans Candida species to spread to the CNS of immunocompetent and immunosuppressed mice. Adult female C57BL/6 mice were treated with prednisolone, intravenously infected with Candida glabrata, Candida krusei and Candida parapsilosis yeasts and then evaluated at the 3rd and 14th days after infection. All Candida species disseminated to the brain from immunocompetent animals and induced local inflammation at the third day post-infection. The immunosuppression resulted in body weight loss, leukopenia and reduced IL-2 production by spleen cell cultures. Higher fungal loads were recovered from the CNS of immunosuppressed mice. Inflammatory infiltration associated to a Th1 subset profile was higher in brain samples from C. krusei immunosuppressed mice compared with immunocompetent ones. Additionally, C. krusei was able to transform into pseudohypha inside microglia in vitro infected cells and also to induce elevated nitric oxide production. Altogether, these results indicate that C. glabrata, C. krusei and C. parapsilosis are able to disseminate to the CNS and promote local inflammation in both immunocompetent and immunosuppressed mice. C. krusei displayed a distinct behavior at the CNS triggering a local Th1 profile. The possible contribution of these non-albicans Candida species to other CNS pathologies as multiple sclerosis, Parkinson’s and Alzheimer’s diseases deserves further attention.

(1→3)-β-d-Glucan in Cerebrospinal Fluid as a Biomarker for Candida and Aspergillus Infections of the Central Nervous System in Pediatric Patients

BACKGROUND

Fungal infections of the central nervous system (FICNS) are important causes of morbidity and mortality among immunocompromised pediatric patients. Standard diagnostic modalities lack the sensitivity for detecting and therapeutically monitoring these life-threatening diseases. Current molecular methods remain investigational. (1→3)-β-d-glucan (BDG) is a cell wall component found in several fungal pathogens, including Candida and Aspergillus spp. Detecting BDG in cerebrospinal fluid (CSF) may be an important approach for detecting and therapeutically monitoring FICNS. To date, there has been no study that has investigated the effectiveness of CSF BDG as a diagnostic and therapeutic marker of FICNS in children.

METHODS

Serial BDG levels were measured in serum and CSF samples obtained from pediatric patients (aged 0-18 years) with a diagnosis of probable or proven Candida or Aspergillus CNS infection.

RESULTS

Nine cases of FICNS were identified in patients aged 1 month to 18 years. Two patients were infected with an Aspergillus species, and 7 patients were infected with a Candida species. All the patients at baseline had detectable BDG in their CSF. Among 7 patients who completed therapy for an FICNS, all elevated CSF BDG levels decreased to <31 pg/mL. At the time of this writing, 1 patient was still receiving therapy and continued to have elevated BDG levels. One patient died from overwhelming disseminated candidiasis. The lengths of therapy for these 9 children ranged from 2 weeks to 28 months.

CONCLUSION

The BDG assay is useful in diagnosing and therapeutically monitoring Candida and Aspergillus CNS infections in pediatric patients.

MRI-DWI improves the early diagnosis of brain abscess induced by Candida albicans in preterm infants

OBJECTIVE

To investigate the diagnostic value of magnetic resonance imaging (MRI) in brain abscess induced by invasive fungal infection (IFI) of the central nervous system.

METHODS

The clinical data of eight preterm infants with IFI of the central nervous system were retrospectively analyzed. All these eight children received three sequential brain MRI modes T1WI, T2WI and DWI during hospitalization and after discharge.

RESULTS

All these eight preterm infants were infected with Candida albicans, seven of which were manifested by brain abscess and four were accompanied by meningitis. MRI of seven infants with brain abscess indicated extensive invasion including involvement of subcortical white matter, deep periventricular white matter and semiovale center white matter. MRI examination was conducted within 11 d following infection on four cases and showed diffuse or multiple miliary nodules, hyper-intense signal on DWI, while insignificant signal changes on T1WI and T2WI. DWI signal nearly disappeared three weeks later. T1WI/T2WI signal changed most significantly 2-4 weeks following infection, with nodules ring-shaped, hyper-intense signal around T1WI and hypo-intense signal in the center. Signal on T2WI was just on the opposite. Severe cases presented fusion of different degrees. Significant enhanced effect was observed on T1WI. Four weeks later, the lesion gradually became fewer and smaller on T1WI, transferred into dot or line-like hyper-intense signal and presented obviously hypo-intense signal on T2WI. Dynamic MRI of two cases showed delayed myelination and corpus callosum thinning.

CONCLUSION

MRI-DWI and dynamic MRI changes can improve the early diagnosis of brain abscess induced by Candida albicans in preterm infants.

Neonatal candidiasis: results of an 8 year study

BACKGROUND

The aim of the present study was to evaluate the risk factors, demographic features, treatment and clinical outcome associated with candidemia in a neonatal intensive care unit (NICU) within an 8 year period.

METHODS

The data of infants who were diagnosed as having candidemia, were evaluated.

RESULTS

Between January 2000 and December 2007, a total of 28 candidemia episodes were identified in 28 infants. A 1.1% candidemia incidence was documented in the neonatal intensive care unit (NICU). The species most frequently causing candidemia were Candida parapsilosis (57.1%), followed by C. albicans (42.9%). The main predisposing factors for candidemia with C. parapsilosis included presence of maternal pre-eclampsia, prematurity, prolonged mechanical ventilation, prolonged total parenteral nutrition and presence of jaundice. Retinopathy of prematurity and bronchopulmonary dysplasia were the most frequently seen underlying illnesses in infants with C. parapsilosis. In the present study, 13 infants (46.4%) had evidence of organ dissemination. The mortality rate was 42.8% in infants with candidemia. Mean leukocyte counts and mean C-reactive protein were significantly higher in neonates who died compared with those who survived.

CONCLUSION

Candida parapsilosis (57.1%) was the leading causative organism, followed by C. albicans (42.9%) in infants. The rate of organ dissemination in the present cases was high. The mortality rate was 42.8% in infants with candidemia.

Mechanisms of Candida albicans trafficking to the brain

During hematogenously disseminated disease, Candida albicans infects most organs, including the brain. We discovered that a C. albicans vps51Δ/Δ mutant had significantly increased tropism for the brain in the mouse model of disseminated disease. To investigate the mechanisms of this enhanced trafficking to the brain, we studied the interactions of wild-type C. albicans and the vps51Δ/Δ mutant with brain microvascular endothelial cells in vitro. These studies revealed that C. albicans invasion of brain endothelial cells is mediated by the fungal invasins, Als3 and Ssa1. Als3 binds to the gp96 heat shock protein, which is expressed on the surface of brain endothelial cells, but not human umbilical vein endothelial cells, whereas Ssa1 binds to a brain endothelial cell receptor other than gp96. The vps51Δ/Δ mutant has increased surface expression of Als3, which is a major cause of the increased capacity of this mutant to both invade brain endothelial cells in vitro and traffic to the brain in mice. Therefore, during disseminated disease, C. albicans traffics to and infects the brain by binding to gp96, a unique receptor that is expressed specifically on the surface of brain endothelial cells.

During hematogenously disseminated infection, the fungus Candida albicans is carried by the bloodstream to virtually all organs in the body, including the brain. C. albicans infection of the brain is a significant problem in premature infants with disseminated candidiasis. To infect the brain, C. albicans must adhere to and invade the endothelial cells that line cerebral blood vessels. These endothelial cells express unique proteins on their surface that are not expressed by endothelial cells of other vascular beds. Here, we show that C. albicans infects the brain by binding to gp96, a heat shock protein that is uniquely expressed on the surface of brain endothelial cells. Gp96 is bound by the C. albicans Als3 invasin, which induces the uptake of this organism by brain endothelial cells. The C. albicans Ssa1 invasin also mediates fungal uptake by brain endothelial cells, but does so by binding to a receptor other than gp96. Thus, during hematogenously disseminated infection, C. albicans traffics to and infects the brain by binding to gp96, a receptor that is expressed specifically on the surface of brain endothelial cells.

Neonatal Candida spp. infections: an update

Candida-related morbidity and mortality have increased in neonatal intensive care units (NICUs) in the last 20 years. Invasive fungal infections (IFIs) in preterm infants are associated with high severity, high attributable mortality, substantial morbidity and poor outcomes owing to the frequent association with late neurodevelopmental impairment and retinopathy of prematurity in the survivors. Preterm very-low birth weight infants in NICUs have a specific, increased risk for IFIs, mainly because up to 60% of them may become colonized during their first month of life. Prevention of Candida colonization and infection is the key in these settings of unique patients, and solid data have recently been added to the very first promising results obtained in the early 2000’s with administation of fluconazole. In a multicenter randomized trial, this azole caused a striking reduction in the incidences of Candida spp. colonization (from 33 to 9%) and infection (from 13.2 to 3.2%), with no occurrence of significant side-effects and no signs of selective resistance during the 15-month study period. New guidelines incorporating the recent multicenter results are urgently needed.

Invasive Candida infections in the neonate

Advances in medical therapy have increased premature infant survival. A rise in Candida infections in neonatal intensive care units (NICUs) has followed. Once considered a contaminant, Candida is now recognized as a major cause of mortality and morbidity within these units. We will examine what is known about the epidemiology, risk factors and end-organ involvement of Candida infections with a focus on invasive disease. In addition, diagnostic alternatives to traditional blood culture, experience with antifungal agents for prophylaxis and therapeutic options, including newer antifungal agents, will be presented.

Fungal infection in the very low birthweight infant

PURPOSE OF REVIEW

Fungal infections are prevalent in very low birthweight (<1500 g) infants and are associated with significant morbidity and mortality. A better understanding of the adherence factors, molecular diagnostics and risk factors for invasive fungal infection are important in treatment and prevention.

RECENT FINDINGS

Animal studies have demonstrated that Candida readily adheres to apical microvilli and the junctions between enterocytes. Although antibiotics facilitate colonization, dissemination occurs with immunosuppression. The INT1 gene is associated with enhanced colonization and dissemination in these animal models. Dissemination is probably caused by yeast cell adherence and invasion, whereas tissue injury may be related to filamentous formation. Polymerase chain reaction techniques have demonstrated promise in neonatal patients and may not only detect bloodstream infection, but fungal infection at other sites. At the time of fungal sepsis, less than 28 weeks' gestation, thrombocytopenia, and previous exposure to broad-spectrum antibiotics continue to be risk factors for infection. Empiric therapy is still being defined and investigated. Fluconazole prophylaxis should be strongly considered in the most immature infants.

SUMMARY

Preventative strategies against fungal colonization and infection are critical in high-risk very low birthweight infants. Also promising is the ability of molecular diagnostics to detect infection earlier, allowing for prompt treatment, including central venous catheter removal. Identifying the highest risk very low birthweight infants for prophylaxis and empiric therapy may lead to better outcomes. Multicenter clinical trials of fluconazole prophylaxis to confirm its safety and efficacy, and of empiric treatment to test safety and outcomes are urgently needed.

Clinical microbiology of bacterial and fungal sepsis in very-low-birth-weight infants

Twenty percent of very-low-birth-weight (<1500 g) preterm infants experience a serious systemic infection, and despite advances in neonatal intensive care and antimicrobials, mortality is as much as threefold higher for these infants who develop sepsis than their counterparts without sepsis during their hospitalization. Outcomes may be improved by preventative strategies, earlier and accurate diagnosis, and adjunct therapies to combat infection and protect the vulnerable preterm infant during an infection. Earlier diagnosis on the basis of factors such as abnormal heart rate characteristics may offer the ability to initiate treatment prior to the onset of clinical symptoms. Molecular and adjunctive diagnostics may also aid in diagnosing invasive infection when clinical symptoms indicate infection but no organisms are isolated in culture. Due to the high morbidity and mortality, preventative and adjunctive therapies are needed. Prophylaxis has been effective in preventing early-onset group B streptococcal sepsis and late-onset Candida sepsis. Future research in prophylaxis using active and passive immunization strategies offers prevention without the risk of resistance to antimicrobials. Identification of the differences in neonatal intensive care units with low and high infection rates and implementation of infection control measures remain paramount in each neonatal intensive care unit caring for preterm infants.