Fungal central nervous system infections: prevalence and diagnosis

Case Report: An Intracranial Aspergillus Infection with Cyst Formation

Intracranial fungal infection is a rare condition that often requires surgical intervention. In this study, we present a case of intracranial fungal infection with a space-occupying effect and a long medical history of five years. We comprehensively evaluated the medical history, symptoms, imaging manifestations, and pathological examinations of the patient to confirm this rare case of fungal infection with cyst formation. Moreover, we reviewed the literature on intracranial fungal infection, hoping to draw awareness and attention to this rare disease.

Forensic Neuropathologic Phenotypes of Fungal Central Nervous System Infections: A Case Series

ABSTRACT

Fungal infections of the central nervous system (FI-CNS) are life-threatening infections that most commonly affect immunocompromised individuals, but immunocompetent individuals may also be infected. Although FI-CNS are relatively rare, the prevalence of FI-CNS is on the rise because of the increasing number of transplant recipients, human immunodeficiency virus-infected individuals, and use of immunosuppressive therapies. Most cases of FI-CNS originate from outside the central nervous system. The etiologic fungi can be classified into 3 fungal groups: molds, dimorphic fungi, and yeasts. The clinical presentation of FI-CNS is highly variable and may be difficult to diagnose premortem. We present a case series of 3 patients, each infected by 1 representative species from each of the 3 fungal groups (Aspergillus species, Blastomyces species, Candida species) to illustrate different neuropathologic phenotypes of FI-CNS. All 3 patients had no history of immunodeficiency and were not suspected to have FI-CNS until they were diagnosed at autopsy. Fungal infections of the central nervous system are often fatal due to delayed diagnosis and diagnostic testing. Awareness of such poly-phenotypic manifestations of FI-CNS will be helpful in reducing delayed diagnosis. It is important for clinicians to include FI-CNS on the differential diagnosis when radiographic findings are nonspecific.

Challenging diagnosis of chronic cerebral fungal infection: Value of (1→3)-ß-D-glucan and mannan antigen testing in cerebrospinal fluid and of cerebral ventricle puncture

Primary fungal infection of the central nervous system (CNS) is rare but often associated with severe prognosis. Diagnosis is complicated since cerebrospinal fluid (CSF) samples obtained from lumbar puncture usually remain sterile. Testing for fungal antigens in CSF could be a complementary diagnostic tool. We conducted such measurements in CSF from patients with CNS fungal infection and now discuss the usefulness of ventricular puncture. Mannan and (1→3)ß-D-glucan (BDG) testing were retrospectively performed in CSF samples from three patients with proven chronic CNS fungal infection (excluding Cryptococcus), and subsequently compared to 16 controls. Results from lumbar punctures and those from cerebral ventricles were confronted. BDG detection was positive in all the CSF samples (from lumbar and/or ventricular puncture) from the three confirmed cases. In case of Candida infection, mannan antigen measurement was positive in 75% of the CSF samples. In the control group, all antigen detections were negative (n = 15), except for one false positive. Faced with suspected chronic CNS fungal infection, measurement of BDG levels appears to be a complementary diagnostic tool to circumvent the limitations of mycological cultures from lumbar punctures. In the event of negative results, more invasive procedures should be considered, such as ventricular puncture.

Membranous nephropathy with pulmonary cryptococcosis with improved 1-year follow-up results: A case report

Cryptococcosis is frequently found in immunosuppressed patients. It is also a significant opportunistic infection in non-immunocompromised individuals. In this study, we present a rare case of membranous nephropathy (MN) with pulmonary cryptococcosis. A 33-year-old man with MN was referred to our hospital because of dyspnea and weakness for 1 week. Before the above symptoms occurred, the dose of Cyclosporin A was increased again for relapse of MN. Multiple massive or patchy high-density shadows were present on computed tomography of the lung. Initially the patient underwent empirical anti-bacterial therapy, which turned out to be ineffective. As the results of serum cryptococcal latex agglutination tests were positive, the administration of anti-fungal drugs was prescribed. The results of fungal culture and pathologic examination of the lung tissue revealed the findings consistent with Cryptococcus neoformans. The patient was successfully treated with voriconazole followed by fluconazole with satisfactory result. Therefore, in patients with chronic kidney disease, lung lesions with poor bactericidal effects of cephalosporins need further examination to make sure whether there is pulmonary cryptococcosis. Early diagnosis and treatment might contribute to good results. It is a problem worthy of consideration that whether immunosuppressive agents need to be discontinued or not during antifungal therapy.

Candida meningitis in neurosurgical patients: a single-institute study of nine cases over 7 years

Candida meningitis in neurosurgical patients is relatively unusual but is associated with a high mortality rate. We present our experience with this infection and discuss the clinical characteristics, treatment options and outcomes. We retrospectively reviewed neurosurgical patients with multiple positive cerebrospinal fluid (CSF) culture results in our hospital from January 2013 to December 2019. Nine patients were available for review according to our inclusion and exclusion criteria. Four species of Candida were isolated from the CSF samples and Candida albicans accounted for half of all infections. Eight infections were associated with ventricle peritoneal shunt, lumbar cistern peritoneal shunt or external ventricular drain. All of these foreign intracranial materials were removed or changed and all the patients received antifungal treatment, including fluconazole and/or voriconazole. It is associated with severe long-term outcomes in survivors and a mortality rate that reaches 11.1%. Prior treatments with broad-spectrum and high-grade antibiotics and anaemia are possible risk factors for Candida meningitis. We advise that foreign intracranial material should be removed or changed as early as possible and the timing of re-shunt operation can be 1 month after control of Candida meningitis has been achieved, with several negative CSF culture results.

Brain abscess due to Candida glabrata in an immunocompetent patient. A case report with update and literature review

Candida spp. brain abscess is scare. Clinical presentation is unspecific. Diagnosis requires mycological culture of a puncture or biopsy specimen. Therapeutic management is based on prolonged course of azole or liposomal amphotericin B. We reported the case of Candida glabrata brain abscess in a 27 year-old female patient, with no past history and not secondary to candidemia. The fungus was isolated from a puncture of abscess with complete resection. The outcome was favorable under antifungal treatment by voriconazole.

Pediatric Giant Cerebral Candida Abscess: A Case Report

Fungal infections of the central nervous system and pediatric brain abscess are rare but serious conditions in terms of morbidity and mortality that need immediate diagnosis and treatment. It can be seen in congenital or acquired immunosuppressed patients as opportunistic infections as well as in low-birth-weight, premature infants with ventriculoperitoneal shunt, external ventricular drainage, or with a history of craniotomy. Our aim is to emphasize the giant cerebral Candida abscess of a 13-month-old female infant who previously had eight ventriculoperitoneal shunt operations due to hydrocephalus. The patient was taken to pediatric emergency care with complaints of feeding difficulty and discomfort and was hospitalized due to the detection of an intracranial mass by contrast-enhanced brain tomography. After total excision of the mass with its capsule, the patient was pathologically diagnosed with Candida abscess, and the treatment was started. The patient was discharged by the end of the 6th week.

Fungal infections in pediatric neurosurgery

INTRODUCTION

Invasive mycosis of the central nervous system represent a diverse group of diseases that have gradually emerged as not only opportunistic infections in patients with immune susceptibility due to congenital and acquired deficiency, immunomodulation, solid organ and stem cell transplantation, hematological malignancies, and chronic steroid use but also in selected risk populations such as low weight preterm infants, patients with shunted hydrocephalus and external ventricular drainages, skull base surgery, and head injury.

OBJECTIVES

The purpose of this review is to familiarize the pediatric neurosurgeon with the most common mycosis and their clinical scenarios which can be encountered in the clinical practice, with special emphasis on clinical, radiological, and laboratory diagnosis beyond classical microorganism cultures as well as options in medical and surgical treatment given the high incidence of morbidity and mortality associated with these challenging entities.

METHODS

We conducted an online database review (Ovid, PubMed) gathering relevant English language literature published in the last 20 years with special emphasis on recent breakthroughs in the diagnosis and treatment of invasive mycosis of the CNS as well as reported cases within the pediatric neurosurgical literature and their surgical management.

RESULTS

Fungal agents capable of invading the CNS can behave as aggressive entities with rapid progression manifesting as overwhelming meningoencephalitis with vascular compromise or can lead to space-occupying lesions with abscess formation which require prompt diagnosis by either laboratory identification of the components of these biological agents and their host response or by obtaining tissue specimens for microbiological identification which may not be straightforward due to prolonged culture time.

CONCLUSION

Following a high degree of suspicion with prompt initiation of antifungal agents and reversal of potential immunosuppressant therapies along with neurosurgical evacuation of intracranial collections or removal of infected hardware (CSF shunts) can lead to more optimistic outcomes of these complex clinical scenarios.

Molecular diagnosis of invasive mycoses of the central nervous system

INTRODUCTION

In September 2012, the Centers for Disease Control and Prevention (CDC) began investigating an outbreak of fungal meningitis among patients who had received contaminated preservative-free methyl prednisolone acetate injections from the New England Compounding Center in Framingham, Massachusetts. Thousands of patients were potentially exposed to tainted corticosteroids, but establishing the diagnosis of fungal meningitis during the nationwide outbreak was difficult because little was known about the natural history of the disease. Areas covered: The challenges associated with this outbreak highlighted the need for rapid and reliable methodologies to assist in the diagnosis of invasive mycoses of the central nervous system (IMCNS), which may be devastating and difficult to treat. In this paper, we review the causative agents of these potentially-lethal infections, which include cryptococcal meningitis, cerebral aspergillosis, and hematogenous Candida meningoencephalitis. Expert commentary: While microscopy, culture, and histopathologic identification of fungal pathogens remain the gold standard for diagnosis, new platforms and species-specific assays have recently emerged, including lateral flow immunoassays (LFA), matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and multiplex PCR in conjunction with magnetic resonance (MR) to potentially aid in the diagnosis of IMCNS.

Cryptococcosis mimicking lung carcinoma with brain metastases in an immunocompetent patient

Cryptococcosis is a fungal infection caused by Cryptococcus spp. that enters the body via inhalation. This ubiquitous yeast has gained notoriety as an opportunistic pathogen in the immunosuppressed population. The authors report a case of a previously-well adult male presented with left-sided weakness. Imaging demonstrated a pulmonary mass and 2 contrast-enhancing intracranial lesions-all features suggestive of a primary lung carcinoma with brain metastases. However, further investigations confirmed disseminated cryptococcosis, without evidence of malignancy. The patient was successfully treated with a course of antifungals. To the authors' knowledge, this is the first reported case of dissemintated cryptococcosis in an immunocompetent adult male, simulating as primary lung carcinoma with brain metastases.

Don't drink in the valley

A 39-year-old man presented with chronic headaches and intermittent blurred vision with previous neuroimaging and blood work that was reportedly normal. He had papilledema and further questioning elicited a history of extensive alcohol use, unexplained weight loss, and night sweats. Magnetic resonance imaging of the brain demonstrated communicating hydrocephalus and leptomeningeal enhancement. The patient underwent ventriculoperitoneal shunt placement and leptomeningeal biopsy, which was initially unrevealing. Cerebrospinal fluid eventually yielded positive titers for coccidioides, a diagnosis that was confirmed by biopsy culture results.

Different Brain Regions are Infected with Fungi in Alzheimer's Disease

The possibility that Alzheimer's disease (AD) has a microbial aetiology has been proposed by several researchers. Here, we provide evidence that tissue from the central nervous system (CNS) of AD patients contain fungal cells and hyphae. Fungal material can be detected both intra- and extracellularly using specific antibodies against several fungi. Different brain regions including external frontal cortex, cerebellar hemisphere, entorhinal cortex/hippocampus and choroid plexus contain fungal material, which is absent in brain tissue from control individuals. Analysis of brain sections from ten additional AD patients reveals that all are infected with fungi. Fungal infection is also observed in blood vessels, which may explain the vascular pathology frequently detected in AD patients. Sequencing of fungal DNA extracted from frozen CNS samples identifies several fungal species. Collectively, our findings provide compelling evidence for the existence of fungal infection in the CNS from AD patients, but not in control individuals.

Cryptococcus neoformans in the respiratory tract of squirrels, Callosciurus finlaysonii (Rodentia, Sciuridae)

Cryptococcosis is a fungal disease acquired from the environment, for which animals may serve as sentinels for human exposure. The occurrence of Cryptococcus spp. in the respiratory tract of 125 squirrels, Callosciurus finlaysonii, trapped in Southern Italy, was assessed. Upon examination of nasal swabs and lung tissue from each individual, a total of 13 (10.4%) animals scored positive for yeasts, 7 for Cryptococcus neoformans (C.n.) (5.6%) and 6 for other yeasts (4.8%). C.n. was isolated from the nostrils and lungs, with a high population size in nostrils. Two C.n. molecular types, VNI and VNIV, were identified, with C.n. var. grubii VNI the most prevalent. Phylogenetic analyses of ITS+ and URA5 sequences revealed that C.n. isolates were genetically similar to isolates from a range of geographical areas and hosts. Results suggest that C.n. can colonize or infect the respiratory tract of C. finlaysonii. The high occurrence and level of colonization of nasal cavities might be an indicator of environmental exposure to high levels of airborne microorganism. The close phylogenetic relationship of C.n. strains from squirrels with those from human and other animal hosts suggests a potential role for these animals as "sentinels" for human exposure.

Role of Coccidioides Antigen Testing in the Cerebrospinal Fluid for the Diagnosis of Coccidioidal Meningitis

BACKGROUND

Coccidioidal meningitis (CM), a common cause of chronic meningitis in endemic area, is usually diagnosed by detection of anti-Coccidioides antibodies in cerebrospinal fluid (CSF), and findings may be negative in up to one-third of cases. CSF cultures and cytology are infrequently positive. Antigen detection has been used for the diagnosis of other forms of coccidioidomycosis and meningitis caused by other mycoses. The purpose of this study was to assess the diagnostic utility of CSF Coccidioides antigen (CAg) detection for the diagnosis of CM.

METHODS

The medical records of patients with clinically suspected meningitis, in whom CSF was tested for Coccidioides antibodies and CAg, were retrospectively reviewed, and CSF CAg testing was prospectively conducted in patients with CM. All specimens were submitted for CAg testing.

RESULTS

Thirty-six patients with 42 episode of CM were studied. The sensitivity and specificity of CAg were 93% and 100%, respectively. Cultures of CSF were positive in 7%, antibodies were demonstrated by immunodiffusion in 67% and complement fixation in 70%, and immunoglobulin M and G antibodies were demonstrated by enzyme immunoassay in 8% and 85%, respectively.

CONCLUSIONS

Testing CSF for CAg is a useful addition to diagnostic methods in suspected CM and complements testing with CSF antibodies and culture.