Fungal and Parasitic CNS Infections

Comparative study of pathogen detection methods for central nervous system infections: laboratory testing of tuberculous meningitis

BACKGROUND

Tuberculous meningitis (TBM) is a severe central nervous system (CNS) infection with a challenging diagnosis due to inadequate detection methods. This study evaluated current clinical detection methods and their applicability.

METHODS

A cohort of 514 CNS infection patients from 2018 to 2020 was studied. Data on general demographics, Cerebrospinal Fluid (CSF) analysis, epidemiology, and clinical outcomes were collected. TBM patients were identified, and the sensitivities of mmetagenomic next-generation sequencing (NGS), GeneXpert, and microbial culture were compared. Kappa statistic assessed the consistency between methods.

RESULTS

Among the patients involved, TBM (29%) and neurosyphilis (25%) were the two most prevalent CNS infections. CSF analysis indicated that 76% of patients had leukocytosis, suggesting a potential CNS inflammation. In TBM cases, 92.5% had elevated CSF protein and leukocyte counts. Moreover, the percentage of positive mNGS results was 55.6%. GeneXpert and MTB cultures alone had lower sensitivity, but combined use resulted in a 53.4% positive rate.

CONCLUSIONS

This study highlights the high sensitivity of mNGS, comparable to GeneXpert and MTB culture. The combined methods are cost-effective and straightforward, and can partially substitute for mNGS, offering valuable alternatives for TBM diagnosis and providing insights into multiple diagnostic strategies in clinical practice.

Metagenomic next-generation sequencing could play a pivotal role in validating the diagnosis of invasive mold disease of the central nervous system

Background

Invasive mold diseases of the central nervous (CNS IMD) system are exceedingly rare disorders, characterized by nonspecific clinical symptoms. This results in significant diagnostic challenges, often leading to delayed diagnosis and the risk of misdiagnosis for patients. Metagenomic Next-Generation Sequencing (mNGS) holds significant importance for the diagnosis of infectious diseases, especially in the rapid and accurate identification of rare and difficult-to-culture pathogens. Therefore, this study aims to explore the clinical characteristics of invasive mold disease of CNS IMD in children and assess the effectiveness of mNGS technology in diagnosing CNS IMD.

Methods

Three pediatric patients diagnosed with Invasive mold disease brain abscess and treated in the Pediatric Intensive Care Unit (PICU) of the First Affiliated Hospital of Zhengzhou University from January 2020 to December 2023 were selected for this study.

Results

Case 1, a 6-year-old girl, was admitted to the hospital with "acute liver failure." During her hospital stay, she developed fever, irritability, and seizures. CSF mNGS testing resulted in a negative outcome. Multiple brain abscesses were drained, and Aspergillus fumigatus was detected in pus culture and mNGS. The condition gradually improved after treatment with voriconazole combined with caspofungin. Case 2, a 3-year-old girl, was admitted with "acute B-lymphoblastic leukemia." During induction chemotherapy, she developed fever and seizures. Aspergillus fumigatus was detected in the intracranial abscess fluid by mNGS, and the condition gradually improved after treatment with voriconazole combined with caspofungin, followed by "right-sided brain abscess drainage surgery." Case 3, a 7-year-old girl, showed lethargy, fever, and right-sided limb weakness during the pending chemotherapy period for acute B-lymphoblastic leukemia. Rhizomucor miehei and Rhizomucor pusillus was detected in the cerebrospinal fluid by mNGS. The condition gradually improved after treatment with amphotericin B combined with posaconazole. After a six-month follow-up post-discharge, the three patients improved without residual neurological sequelae, and the primary diseases were in complete remission.

Conclusion

The clinical manifestations of CNS IMD lack specificity. Early mNGS can assist in identifying the pathogen, providing a basis for definitive diagnosis. Combined surgical treatment when necessary can help improve prognosis.

Diversity and Surgical Management of Intracranial Fungal Infections

Intracranial fungal infection is a rare entity. This disease is mainly concentrated in dry and hot climates, such as India, Africa, California, and usually occurs in patients with immune deficiency. Now, we retrospectively analyzed the clinical manifestations, pathologic manifestations, imaging features, surgical methods, and prognosis of 4 patients with fungal infection who were confirmed by postoperative pathology. Intermittent pricking on the right face was presented in 2 patients, headache in 2 patients, orbital apex syndrome in 2 patients, and 1 patient presented with fever. Imaging showed the lesions of all patients were located in the right temporal, including 2 patients involving the right orbital, 1 patient involving the right trigeminal semilunar ganglion, 1 patient involving the right brainstem and tentorium cerebellum, 1 patient involving the right internal carotid artery. Craniotomy was performed in 2 patients, endoscopic biopsy in 1 patient, and stereotactic surgery in 1 patien. Aspergilloma was the most common pathogenic bacteria. One patient relapsed repeatedly and died. Secondary aneurysm complicated with subarachnoid hemorrhage occurred in 1 patient. Therefore, the author confirmed that intracranial fungal infection has diverse clinical, imaging, and pathologic manifestations. Neurosurgeons should be aware of the possibility of intracranial fungal infection when they find abnormal intracranial lesions, neurologic deficits, and inflammation of paranasal sinuses. Combining multiple clinical data may help doctors to improve the accuracy of diagnosis. Individualized and diversified surgical protocols should be selected for diverse lesions. Notably, secondary intracranial fungal vasculitis is common, with high mortality and disability rates.

Effects of modified external ventricular drainage vs. an Ommaya reservoir in the management of hydrocephalus with intracranial infection in pediatric patients

Background

Hydrocephalus with intracranial infection (HII) may cause pathological changes in brain tissue structure and irreversible damage to the nervous system. However, intracranial infection is a contraindication to ventriculo-peritoneal (VP) shunt surgery, and the prognosis is improved by early infection control and intracranial pressure reduction. This study evaluated the safety and efficacy of the Ommaya reservoir vs. modified external ventricular drainage (M-EVD) in the management of HII in pediatric patients.

Methods

This retrospective controlled study included 45 pediatric patients with HII treated with an Ommaya reservoir (n = 24) or M-EVD (n = 21) between January 2018 and December 2022. Clinical outcomes, cerebrospinal fluid (CSF) test results, complications, and outcomes were compared between the Ommaya reservoir and M-EVD groups.

Results

No patient died during the follow-up period. The two groups were similar regarding age, sex, admission temperature, weight, preoperative serum protein and albumin concentrations, CSF analysis (white blood cell count, glucose concentration, and protein content), and clinical symptoms (P > 0.05). Both groups had significant changes in the CSF test results postoperatively compared with preoperatively (P < 0.05). In the M-EVD group, the median days for 13 children to remove the external drainage tube and receive VP shunt was 19 days. The longest drainage tube retention time was 61 days, and there was no intracranial infection or serious complication related to the drainage tube. After the placement of the Ommaya, the median time required for CSF to return to normal was 21 days, and a total of 15 patients underwent VP shunt surgery.

Conclusion

The Ommaya reservoir and M-EVD are safe and effective for pediatric patients with HII. Both methods reduce the intracranial pressure and alleviate the symptoms of hydrocephalus, although there are differences between the two methods.

Pediatric Headache Attributed to Infection

Pediatric headaches attributed to infection are typically related to non-life threatening illnesses such as upper respiratory tract infections and rhinosinusitis. Although less common, secondary headaches related to life threatening infections are most frequently associated with meningitis. This review provides an overview of the International Classification of Headache Disorders third edition (ICHD-3) categories of infections contributing to secondary headache, describes clinical presentation, and presents a focused review on relevant diagnoses associated with this headache type. An understanding of headache attributed to infection will provide the foundation on distinguishing secondary headaches from various etiological infectious disorders.

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.

An unexpected intracerebral lesion - case report of a superinfected aspergillosis mimicking a brain metastasis

Background

Invasive aspergillosis of the central nervous system is a rare but increasingly prevalent disease. We present the unusual case of an immunosuppressed patient suffering from unexpected superinfected invasive aspergillosis with cerebral, pulmonal, and adrenal manifestations, mimicking a metastasized bronchial carcinoma. This report reveals the importance of including aspergillosis in the differential diagnosis of a cerebral mass lesion in the light of unspecific clinical findings.

Case presentation

A 58-year-old immunocompromised female presented to our emergency department with a single tonic-clonic seizure. Imaging showed a ring enhancing cerebral mass with perifocal edema and evidence of two smaller additional hemorrhagic cerebral lesions. In the setting of a mass lesion in the lung, and additional nodular lesions in the left adrenal gland the diagnosis of a metastasized bronchus carcinoma was suspected and the cerebral mass resected. However, histology did not reveal any evidence for a neoplastic lesion but septate hyphae consistent with aspergillus instead and microbiological cultures confirmed concomitant staphylococcal infection.

Conclusions

A high index of suspicion for aspergillus infection should be maintained in the setting of immunosuppression. Clinical and radiological findings are often unspecific and even misleading. Definite confirmation usually relies on tissue diagnosis with histochemical stains. Surgical resection is crucial for establishing the diagnosis and guiding therapy with targeted antifungal medications.

A Retrospective Analysis of Invasive Fungal Diseases (IFD) of the Central Nervous System in Children With Lymphoid Malignancies

BACKGROUND

Outcomes of childhood hematolymphoid malignancies have improved several fold because of immunosuppressive chemotherapy and broad-spectrum antibiotics for managing febrile neutropenia. An apparent trade-off has been an increase in invasive fungal disease (IFD), affecting multiple organs. We report the diagnostic and therapeutic challenges in 8 children with lymphoid cancers who developed intracranial (IC) fungal abscesses between 2010 and 2017.

METHODS

Children below 15 years of age undergoing treatment for leukemia/lymphoma with clinicoradiologic and microbiologic evidence of IC fungal abscess were included. Demographic details, clinical profile, and management were retrospectively audited. Treatment was guided by European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) definitions for IFD with therapeutic drug monitoring (TDM)-directed azole dosing, and surgical intervention.

RESULTS

Eight patients (4 B-cell acute lymphoblastic leukemia, 2 relapsed B-cell acute lymphoblastic leukemia, and 2 non-Hodgkin lymphoma) were eligible for analysis. Proven, probable, and possible IFDs were seen in 2 (25%), 4 (50%), and 2 (25%) patients, respectively. Proven IFDs were invasive mucormycosis with remaining having mold infections. Cerebrospinal fluid galactomannan was positive in all 4 patients in whom it was tested. TDM was possible in 5/8 (63%) patients. Antifungal therapy was given for a median period of 4.2 months with 5 (63%) patients having complete resolution. Three (37%) patients expired, of which 2 were attributable to IFDs.

CONCLUSIONS

IC fungal abscesses in children can cause significant morbidity and mortality in children with hematolymphoid cancers. Evaluation of cerebrospinal fluid galactomannan may help in early diagnosis and therapy. Prolonged antifungal therapy steered by TDM can help achieve resolution in some cases.

Optimizing Laboratory Diagnostic Services for Infectious Meningitis in the Meningitis Belt of sub-Saharan Africa

For longer than a century, the "meningitis belt" of sub-Saharan Africa has experienced the largest-ever global meningitis epidemic. Whereas HIV-associated immunosuppression drives higher susceptibility to environmental infectious organisms with tropism for the central nervous system (CNS), most diagnostic laboratories in the belt stick to N. meningitidis, H. influenzae, and S. pneumoniae. Cryptococcus neoformans has been the leading cause of death (incidence, 89%; death, 75%). To establish whether diagnostic services target geographically important pathogens, there is a need to know the current spectrum of etiology. Given Africa's agro-silvo-pastoralism, the One Health diagnostic approach is recommended. Considering  multipathogen detection capacity, needed speed for corticosteroid therapy decision, and susceptibility/resistance to antimicrobials with improved CNS penetration, proposed laboratory categorization will help neurologists to choose suitable services.

Apparent performance of metagenomic next-generation sequencing in the diagnosis of cryptococcal meningitis: a descriptive study

INTRODUCTION

In recent years, metagenomic next-generation sequencing (mNGS) has become widely used in medical microbiology to detect pathogen infection.

AIM

We aimed to assess the diagnostic performance of mNGS of cerebrospinal fluid (CSF) for prediction of cryptococcal meningitis (CM).

METHODOLOGY

A comparative evaluation of mNGS (performed on CSF samples) and conventional methods, including India ink staining, culture for fungi and cryptococcal-antigen (CrAg) detection by enzyme immunoassay, was performed on 12 consecutive non-HIV-infected patients with chronic or subacute CM.

RESULTS

India ink staining and culture of the CSF were positive for Cryptococcus in 83.33 % (10/12) of the samples; 100 % (11/11) were positive via CrAg EIA. The mNGS results of the CSF identified DNA sequences corresponding to Cryptococcus in 75 % of samples (9/12). However, the DNA of both C. neoformans s.l. and C. gattii s.l. was detected concurrently in 33.33 % (4/12).

CONCLUSION

mNGS is helpful for identifying Cryptococcus species. The application of mNGS, together with India ink staining, culture methods, and CrAg, may significantly improve the diagnostic precision in CM, thereby informing choice of appropriate antifungal treatment courses.

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.