Central nervous system infections in immunocompromised patients: update on diagnostics and therapy

Clinical features and prognostic model for viral encephalitis after allogeneic haematopoietic stem cell transplantation

The objective of this study was to identify independent prognostic factors of viral encephalitis (VE) after allogeneic haematopoietic stem cell transplantation (allo-HSCT) and establish a prognostic model to identify post-transplant VE patients with a greater likelihood of mortality. Among 5380 patients in our centre from 2014 to 2022, 211 patients who developed VE after allo-HSCT were reviewed in this retrospective study. Prognostic factors were selected, and a prognostic model was constructed using Cox regression analysis. The model was subsequently validated and estimated using the area under the receiver operating characteristic curve (AUC), a calibration plot and decision curve analysis (DCA). Glasgow Coma Scale score <9, lesions >3 lobes on magnetic resonance imaging and severe thrombocytopenia were identified as independent prognostic risk factors for VE patients who underwent allo-HSCT. The prognostic model GTM (GTM is an abbreviation for a model composed of three risk factors: GCS score <9, severe thrombocytopenia [platelet count <20 000 per microliter], and lesions >3 lobes on MRI) was established according to the regression coefficients. The validated internal AUC was 0.862 (95% confidence interval [CI], 0.773-0.950), and the external AUC was 0.815 (95% CI, 0.708-0.922), indicating strong discriminatory ability. Furthermore, we constructed calibration plots that demonstrated good consistency between the predicted outcomes and the observed outcomes. DCA exhibited high accuracy in this system, leading to potential benefits for patients.

Mimicking the brain: Epstein-Barr virus and foreign agents as drivers of neuroimmune attack in multiple sclerosis

T cells have an essential role in adaptive immunity against pathogens and cancer, but failure of thymic tolerance mechanisms can instead lead to escape of T cells with the ability to attack host tissues. Multiple sclerosis (MS) occurs when structures such as myelin and neurons in the central nervous system (CNS) are the target of autoreactive immune responses, resulting in lesions in the brain and spinal cord which cause varied and episodic neurological deficits. A role for autoreactive T cell and antibody responses in MS is likely, and mounting evidence implicates Epstein-Barr virus (EBV) in disease mechanisms. In this review we discuss antigen specificity of T cells involved in development and progression of MS. We examine the current evidence that these T cells can target multiple antigens such as those from pathogens including EBV and briefly describe other mechanisms through which viruses could affect disease. Unravelling the complexity of the autoantigen T cell repertoire is essential for understanding key events in the development and progression of MS, with wider implications for development of future therapies.

Varicella vaccine meningoencephalitis in a child receiving autologous bone marrow transplantation

BACKGROUND

Varicella vaccine, a live-attenuated Oka-strain of varicella zoster virus (VZV), is a recommended childhood vaccine by many countries. As with wild varicella strain, after primary infection, the live-attenuated virus can establish latency in sensory ganglia and reactivate causing vaccine-strain illnesses: herpes zoster (HZ), visceral or peripheral and central nervous system dissemination. We report a case of early reactivation of live-attenuated virus-HZ and meningoencephalitis-in an immunocompromised child.

METHODS

This is a retrospective descriptive report of a case, in a tertiary pediatric hospital, CHU Sainte-Justine (Montréal, Canada).

RESULTS

An 18 month-year old girl diagnosed with a primitive neuro-ectodermal tumor (PNET) received the day prior to diagnosis, a first varicella vaccine (MMRV). She received chemotherapy 20 days post MMRV vaccine and autologous bone marrow transplantation 3 months post vaccination. She was considered not eligible, to acyclovir prophylaxis prior transplantation (positive for VZV IgG and negative for herpes simplex virus IgG by ELISA). At day 1 post transplantation, she developed dermatomal HZ and meningoencephalitis. Oka-strain varicella was isolated, she was treated with acyclovir and foscarnet. Neurologic status improved in 5 days. Control of VZV viral load in cerebrospinal fluid showed a slow decrease to from 5.24 log 10 copies/mL to 2.14 log 10 copies/mL in 6 weeks. No relapse was observed. She recovered without neurological sequelae.

CONCLUSIONS

Our experience highlights the importance of conducting a thorough medical history regarding vaccination and serological status of newly immunocompromised patients. Intensive chemotherapy succeeding live vaccine administration <4 weeks could have influenced early and severe viral reactivation. Early initiation of prophylactic antiviral treatment is questioned in such circumstances.

Differentiating central nervous system infection from disease infiltration in hematological malignancy

Hematological malignancies place individuals at risk of CNS involvement from their hematological disease and opportunistic intracranial infection secondary to disease-/treatment-associated immunosuppression. Differentiating CNS infection from hematological disease infiltration in these patients is valuable but often challenging. We sought to determine if statistical models might aid discrimination between these processes. Neuroradiology, clinical and laboratory data for patients with hematological malignancy at our institution between 2007 and 2017 were retrieved. MRI were deep-phenotyped across anatomical distribution, presence of pathological enhancement, diffusion restriction and hemorrhage and statistically modelled with Bayesian-directed probability networks and multivariate logistic regression. 109 patients were studied. Irrespective of a diagnosis of CNS infection or hematological disease, the commonest anatomical distributions of abnormality were multifocal-parenchymal (34.9%), focal-parenchymal (29.4%) and leptomeningeal (11.9%). Pathological enhancement was the most frequently observed abnormality (46.8%), followed by hemorrhage (22.9%) and restricted diffusion (19.3%). Logistic regression could differentiate CNS infection from hematological disease infiltration with an AUC of 0.85 where, with OR > 1 favoring CNS infection and < 1 favoring CNS hematological disease, significantly predictive imaging features were hemorrhage (OR 24.61, p = 0.02), pathological enhancement (OR 0.17, p = 0.04) and an extra-axial location (OR 0.06, p = 0.05). In conclusion, CNS infection and hematological disease are heterogeneous entities with overlapping radiological appearances but a multivariate interaction of MR imaging features may assist in distinguishing them.

T-cell surveillance of the human brain in health and multiple sclerosis

Circulating and tissue-resident T cells collaborate in the protection of tissues against harmful infections and malignant transformation but also can instigate autoimmune reactions. Similar roles for T cells in the brain have been less evident due to the compartmentized organization of the central nervous system (CNS). In recent years, beneficial as well as occasional, detrimental effects of T-cell-targeting drugs in people with early multiple sclerosis (MS) have increased interest in T cells patrolling the CNS. Next to studies focusing on T cells in the cerebrospinal fluid, phenotypic characteristics of T cells located in the perivascular space and the meninges as well as in the parenchyma in MS lesions have been reported. We here summarize the current knowledge about T cells infiltrating the healthy and MS brain and argue that understanding the dynamics of physiological CNS surveillance by T cells is likely to improve the understanding of pathological conditions, such as MS.

Neurological complications following pediatric allogeneic hematopoietic stem cell transplantation: Risk factors and outcome

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is an efficient treatment for numerous malignant and nonmalignant conditions affecting children. This procedure can result in infectious and noninfectious neurological complications (NCs).

OBJECTIVE

The objective of the study is to examine the incidence, risk factors, and outcomes of NCs in pediatric patients following allogeneic HSCT.

METHODS

We performed a retrospective study of 746 children who underwent 943 allogeneic HSCTs in two large pediatric hospitals in Israel from January 2000 to December 2019.

RESULTS

Of the pediatric patients 107 (14.3%) experienced 150 NCs. The median follow-up was 55 months. Noninfectious NCs were more common than infectious NCs (81.3% vs. 18.7%). Factors significantly associated with type of NC (infectious vs. noninfectious) were underlying disease (immunodeficiency vs. malignant and metabolic/hematologic disease) (p-value = 0.000), and use of immunosuppressive agent, either Campath or ATG (p-value = 0.041). Factors with a significant impact on developing neurological sequelae post-NC were number of HSCT >1 (p-value = 0.028), the use of alemtuzumab as an immunosuppressive agent (p-value = 0.003), and infectious type of NC (p-value = 0.046). The overall survival rate of whole NC-cohort was 44%; one-third of all mortality cases were attributed to the NC. The strongest prognostic factors associated with mortality were older age at HSCT (p-value = 0.000), the use of alemtuzumab as an immunosuppressive agent (p-value = 0.004), and the existence of neurological sequelae (p-value = 0.000). Abnormal central nervous system imaging (p-value = 0.013), the use of alemtuzumab as an immunosuppressive agent (p-value = 0.019), and neurological sequelae (p-value = 0.000) had statistically significant effects on neurological cause of death.

CONCLUSION

Infectious and noninfectious NCs are a significant cause of morbidity and mortality following allogeneic HSCT in children. Further research is required to better understand the risk factors for different NCs and their outcomes regarding sequelae and survival.

Hematopoietic Stem Cell Transplantation-Associated Neurological Complications and Their Brain MR Imaging Findings in a Pediatric Population

Simple Summary

Neurologic complications following a hematopoietic stem cell transplantation (HSCT) can be caused by various etiologies and significantly contribute to morbidity and mortality. The aim of our retrospective study was to determine the prognostic indicators for HSCT-associated neurological complications in pediatric HSCT recipients using their clinical characteristics and brain magnetic resonance imaging (MRI) lesions. The demographics, received treatments, treatment-related morbidities, laboratory findings and brain MRI findings were reviewed and compared among 51 patients who had underwent a brain MRI due to newly developed neurological symptoms or infection signs during HSCT and follow-up period. Children with neurologic complications associated with infectious causes, malignant disease or severe brain MRI abnormalities were more likely to have poor outcome.

Abstract

Purpose: To determine the prognostic indicators for hematopoietic stem cell transplantation (HSCT)-associated neurological complications, the clinical characteristics and brain magnetic resonance imaging (MRI) lesions in pediatric HSCT recipients were reviewed. Methods: This retrospective study included 51 patients who had underwent a brain MRI due to newly developed neurological symptoms or infection signs during chemotherapy or HSCT. We reviewed the demographics, received treatments, treatment-related morbidities, laboratory findings and brain MRI findings, which were compared between good and poor neurologic outcome groups. Results: Thirty-seven patients (72.5%) fully recovered from the neurologic deficits and fourteen (27.5%) persisted or aggravated. The children with an underlying malignant disease had significantly poorer neurological outcomes (p = 0.015). The neurologic complications associated with infection were more frequent in the poor outcome group (p = 0.038). In the neuroimaging findings, the extent of the white matter lesions was significantly higher in the poor outcome group, as was that of abnormal enhancement, ventriculomegaly, cortical change, deep gray matter abnormalities and cerebellar abnormalities. Conclusion: Most children with neurologic complications and neuroimaging abnormalities during HSCT had recovered. However, children with neurologic complications associated with infectious causes, malignant disease or severe brain MRI abnormalities should be more carefully monitored during HSCT.

Neuroimaging of CNS infection in haematological malignancy: important signs and common diagnostic pitfalls

Patients with haematological malignancy are at increased risk of developing central nervous system (CNS) infections, which are associated with significant morbidity and mortality. Neuroimaging plays a pivotal role in the diagnostic pathway of these patients; however, layers of complexity are added to image interpretation by the heterogeneity in imaging manifestations of haematological malignancies in the CNS, overlapping imaging features of CNS infection, treatment-related parenchymal changes and the presence of intracranial comorbidity. In this article, we review important intracranial findings of CNS infection cases accrued in 1,855 studies over more than a decade at a specialist tertiary centre. We offer schema to identify common and important neuroimaging features, discuss key differential diagnoses and frequent diagnostic pitfalls.

CNS Macrophages and Infant Infections

The central nervous system (CNS) harbors its own immune system composed of microglia in the parenchyma and CNS-associated macrophages (CAMs) in the perivascular space, leptomeninges, dura mater, and choroid plexus. Recent advances in understanding the CNS resident immune cells gave new insights into development, maturation and function of its immune guard. Microglia and CAMs undergo essential steps of differentiation and maturation triggered by environmental factors as well as intrinsic transcriptional programs throughout embryonic and postnatal development. These shaping steps allow the macrophages to adapt to their specific physiological function as first line of defense of the CNS and its interfaces. During infancy, the CNS might be targeted by a plethora of different pathogens which can cause severe tissue damage with potentially long reaching defects. Therefore, an efficient immune response of infant CNS macrophages is required even at these early stages to clear the infections but may also lead to detrimental consequences for the developing CNS. Here, we highlight the recent knowledge of the infant CNS immune system during embryonic and postnatal infections and the consequences for the developing CNS.

Mesenchymal stem cells transplantation attenuates brain injury and enhances bacterial clearance in Escherichia coli meningitis in newborn rats

OBJECTIVE

Neonatal meningitis caused by Escherichia coli results in significant mortality and neurological disabilities, with few effective treatments. Recently, we demonstrated that human umbilical cord blood-derived mesenchymal stem cell (hUCB-MSC) transplantation attenuated E. coli-induced severe pneumonia, primarily by reducing inflammation and enhancing bacterial clearance. This study aimed to determine whether intraventricular transplantation of hUCB-MSCs attenuated the brain injury in E. coli meningitis in newborn rats.

METHODS

Meningitis without concomitant bacteremia was induced by intraventricular injection of 5 × 10² colony forming units of K1 (-) E. coli in rats at postnatal day (P)11, and hUCB-MSCs (1 × 10⁵) were transplanted intraventricularly 6 h after induction of meningitis. Antibiotics was started 24 h after modeling.

RESULT

Meningitis modeling induced robust proliferation of E. coli in the cerebrospinal fluid and increased mortality in rat pups, and MSC transplantation significantly reduced this bacterial growth and the mortality rate. Impaired sensorimotor function in the meningitis rats was ameliorated by MSCs injection. MSCs transplantation also attenuated meningitis caused brain injury including cerebral ventricular dilatation, brain cell death, reactive gliosis, and inflammatory response.

CONCLUSION

Intraventricular transplantation of hUCB-MSCs significantly improved survival and attenuated the brain injury via anti-inflammatory and antibacterial effects in experimental neonatal E. coli meningitis.

Disseminated cerebral toxoplasmosis in a patient with chronic lymphocytic leukemia

Infections are one of the most common causes of mortality in immunocompromised patients. In patients diagnosed with hematologic malignancies, treatment with stem cell transplants (SCT) or T-cell suppressing chemotherapy increases the risk of central nervous system (CNS) infections, of which toxoplasmosis is the most common. We report the case of a 63 year-old woman with chronic lymphocytic leukemia (CLL) that presented with gait instability and visual changes. Intracranial lesions were noted on initial neuro-imaging. A rapid decline in the patient's mental status warranted an urgent biopsy of the lesions that revealed tachyzoites consistent with toxoplasmosis. In the presence of diffuse brain lesions that lack a metastatic pattern or contrast enhancement, a common approach is to perform biopsy only after a battery of non-invasive testing. This diagnostic delay may take several days, exposing the patient to a rapidly fatal infection. This report illustrates the utility of early brain biopsy in high-risk patients with hematologic malignancies and CNS lesions.

Sequential Onset of Varicella-Zoster Virus Encephalomeningitis and Progressive Multifocal Leukoencephalopathy in an Allogeneic Hematopoietic Stem Cell Transplant Recipient

Here, we describe a case of sequential varicella-zoster virus encephalomeningitis and progressive multifocal leukoencephalopathy following an allogeneic hematopoietic stem cell transplant procedure. A 37-year-old male patient presented with fever, incomplete paralysis of bilateral legs, and bullous eruptions 8 months after allogeneic transplant. Polymerase chain reaction assays of cerebrospinal fluid samples for varicella-zoster virus were positive. Bullous eruptions and incomplete paralysis of bilateral legs improved after administration of acyclovir. However, higher brain dysfunction was present and getting worse. We detected no herpes simplex virus, varicella-zoster virus, Cytomegalovirus, human herpes virus 6, Epstein-Barr virus, or JC virus in cerebrospinal fluid samples with polymerase chain reaction assays. Pathologic findings and polymerase chain reaction assays with brain biopsy samples revealed that the patient had progressive multifocal leukoencephalopathy. This is the first report of a case showing dual central nervous system infections due to varicella-zoster virus and JC virus after allogeneic stem cell transplant.

Central nervous system infection following allogeneic hematopoietic stem cell transplantation

OBJECTIVE/BACKGROUND

Here, we described the clinical characteristics and outcomes of central nervous system (CNS) infections occurring after allogeneic hematopoietic stem cell transplantation (allo-HSCT) in a single institution over the previous 6 years.

METHODS

Charts of 353 consecutive allogeneic transplant recipients were retrospectively reviewed for CNS infection.

RESULTS

A total of 17 cases of CNS infection were identified at a median of 38 days (range, 10-1028 days) after allo-HSCT. Causative pathogens were human herpesvirus-6 (n=6), enterococcus (n=2), staphylococcus (n=2), streptococcus (n=2), varicella zoster virus (n=1), cytomegalovirus (n=1), John Cunningham virus (n=1), adenovirus (n=1), and Toxoplasma gondii (n=1). The cumulative incidence of CNS infection was 4.1% at 1 year and 5.5% at 5 years.

CONCLUSION

Multivariate analysis revealed that high-risk disease status was a risk factor for developing CNS infection (p=.02), and that overall survival at 3 years after allo-HSCT was 33% in patients with CNS infection and 53% in those without CNS infection (p=.04).

A Diagnostic Dilemma: Similarity of Neuroradiological Findings in Central Nervous System Hemophagocytic Lymphohistiocytosis and Aspergillosis

Central nervous system (CNS) involvement in the context of hemophagocytic lymphohistiocytosis (HLH) is not uncommon. Given the immunosuppressive nature of HLH therapy, infectious complications are also seen. We describe a 9-year-old male who developed acute neurological decline secondary to aspergillosis while undergoing HLH therapy. The significant overlap observed in CNS neuroimaging of HLH and aspergillosis and the subtleties that may help differentiate the two are discussed. The importance of obtaining tissue for definitive diagnosis is underscored.

CNS infections in patients with hematological disorders (including allogeneic stem-cell transplantation)-Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO)

Diagnosis of CNS infections remains a great challenge in patients with hematological disorders since symptoms might both be masked and be mimicked by other conditions such as metabolic disturbances or consequences from antineoplastic treatment. Thus, awareness of this complication is crucial and any suspicion of a CNS infection should lead to timely and adequate diagnostics and treatment to improve the outcome in this population.

Infections of the central nervous system (CNS) are infrequently diagnosed in immunocompetent patients, but they do occur in a significant proportion of patients with hematological disorders. In particular, patients undergoing allogeneic hematopoietic stem-cell transplantation carry a high risk for CNS infections of up to 15%. Fungi and Toxoplasma gondii are the predominant causative agents. The diagnosis of CNS infections is based on neuroimaging, cerebrospinal fluid examination and biopsy of suspicious lesions in selected patients. However, identification of CNS infections in immunocompromised patients could represent a major challenge since metabolic disturbances, side-effects of antineoplastic or immunosuppressive drugs and CNS involvement of the underlying hematological disorder may mimic symptoms of a CNS infection. The prognosis of CNS infections is generally poor in these patients, albeit the introduction of novel substances (e.g. voriconazole) has improved the outcome in distinct patient subgroups. This guideline has been developed by the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) with the contribution of a panel of 14 experts certified in internal medicine, hematology/oncology, infectious diseases, intensive care, neurology and neuroradiology. Grades of recommendation and levels of evidence were categorized by using novel criteria, as recently published by the European Society of Clinical Microbiology and Infectious Diseases.

Cerebral toxoplasmosis in a diffuse large B cell lymphoma patient

Background

Toxoplasmosis is an opportunistic protozoal infection that has, until now, probably been an underestimated cause of encephalitis in patients with hematological malignancies, independent of stem cell or bone marrow transplant. T and B cell depleting regimens are probably an important risk factor for reactivation of a latent toxoplasma infection in these patients.

Case report

We describe a 62-year-old HIV-negative right-handed Caucasian female with systemic diffuse large B cell lymphoma who presented with sudden onset of high fever, headache, altered mental status, ataxia and findings of pancytopenia, a few days after receiving her final, 8^th cycle of rituximab, cyclophosphamide, vincristine, doxorubicin, prednisolone (R-CHOP) chemotherapy regimen. A progression of lymphoma to the central nervous system was suspected. MRI of the head revealed multiple on T2 and fluid attenuated inversion recovery (FLAIR) hyperintense parenchymal lesions with mild surrounding edema, located in both cerebral and cerebellar hemispheres that demonstrated moderate gadolinium enhancement. The polymerase chain reaction on cerebrospinal fluid (CSF PCR) was positive for Toxoplasma gondii. The patient was diagnosed with toxoplasmic encephalitis and successfully treated with sulfadiazine, pyrimethamine and folic acid. Due to the need for maintenance therapy with rituximab for lymphoma remission, the patient now continues with secondary prophylaxis of toxoplasmosis.

Conclusions

With this case report, we wish to emphasize the need to consider cerebral toxoplasmosis in patients with hematological malignancies on immunosuppressive therapy when presenting with new neurologic deficits. In such patients, there are numerous differential diagnoses for cerebral toxoplasmosis, and the CNS lymphoma is the most difficult among all to distinguish it from. If left untreated, cerebral toxoplasmosis has a high mortality rate; therefore early recognition and treatment are of essential importance.

Congenital Toxoplasmosis

Toxoplasmosis is caused by infection with the parasite Toxoplasma gondii. It is one of the most common parasitic infections in humans and is most typically asymptomatic. However, primary infection in a pregnant woman can cause severe and disabling disease in the developing fetus. Recent developments have included increased understanding of the role of parasite genotype in determining infectivity and disease severity. Risk factors for acquisition of infection have been better defined, and the important role of foodborne transmission has been further delineated. In addition, strategies have emerged to decrease mother-to-child transmission through prompt identification of acutely infected pregnant women followed by appropriate treatment. Refined diagnostic tools, particularly the addition of immunoglobulin G avidity testing, allow for more accurate timing of maternal infection and hence better decision making during pregnancy. Congenitally infected children can be treated, beginning in utero and continuing through the first year of life, to ameliorate the severity of disease. However, despite these many advances in our understanding of congenital toxoplasmosis prevention and treatment, significant areas of study remain: we need better drugs, well defined strategies for screening of pregnant women, improved food safety, and improved diagnostic tests.

Fungal central nervous system infections: prevalence and diagnosis

Fungal infections of the central nervous system (CNS) are rare but they pose a significant challenge. Their prevalence spans a wide array of hosts including immunosuppressed and immunocompetent individuals, patients undergoing neurosurgical procedures and those carrying implantable CNS devices. Cryptococcus neoformans and Aspergillus spp. remain the most common pathogens. Magnetic resonance imaging can help localize the lesions, but diagnosis is challenging since invasive procedures may be needed for the retrieval of tissue, especially in cases of fungal abscesses. Antigen and antibody tests are available and approved for use in the cerebrospinal fluid (CSF). PCR-based techniques are promising but they are not validated for use in the CSF. This review provides an overview on the differential diagnosis of the fungal CNS disease based on the host and the clinical syndrome and suggests the optimal use of diagnostic techniques. It also summarizes the emergence of Cryptococcus gatti and an unanticipated outbreak caused by Exserohilum rostratum.

Central nervous system infections in cancer patients and hematopoietic stem cell transplant recipients

Central nervous system (CNS) infections in cancer patients present a diagnostic and therapeutic challenge for clinicians. While CNS infections are not frequent complications of cancer, its therapies, or hematopoietic stem cell transplantation, the importance of CNS infections lies in their propensity to result in profound morbidity and substantial mortality in this vulnerable patient population. With an expanding population of patients with malignant disease undergoing more potent and aggressive therapies and with the advent of newer immunomodulatory agents, the incidence of CNS infectious complications is likely to rise. This chapter will summarize the clinical and diagnostic evaluation of potential infections of the CNS in these patients and will discuss particular pathogens of interest with regard to this at-risk patient population.

Diagnosis and treatment of viral diseases in recipients of allogeneic hematopoietic stem cell transplantation

Viral infections are important causes of morbidity and mortality after allogeneic stem cell hematopoietic transplantation (allo-HSCT). Although most viral infections present with asymptomatic or subclinical manifestations, viruses may result in fatal complications in severe immunocompromised recipients. Reactivation of latent viruses, such as herpesviruses, is frequent during the immunosuppression that occurs with allo-HSCT. Viruses acquired from community, such as the respiratory and gastrointestinal viruses, are also important pathogens of post-transplant viral diseases. Currently, molecular diagnostic methods have replaced or supplemented traditional methods, such as viral culture and antigen detection, in diagnosis of viral infections. The utilization of polymerase chain reaction facilitates the early diagnosis. In view of lacking efficacious agents for treatment of viral diseases, prevention of viral infections is extremely valuable. Application of prophylactic strategies including preemptive therapy reduces viral infections and diseases. Adoptive cellular therapy for restoring virus-specific immunity is a promising method in the treatment of viral diseases.

Diagnostic performance of an Aspergillus-specific nested PCR assay in cerebrospinal fluid samples of immunocompromised patients for detection of central nervous system aspergillosis

Central nervous system (CNS) invasive aspergillosis (IA) is a fatal complication in immunocompromised patients. Confirming the diagnosis is rarely accomplished as invasive procedures are impaired by neutropenia and low platelet count. Cerebrospinal fluid (CSF) cultures or galactomannan (GM) regularly yield negative results thus suggesting the need for improving diagnostic procedures. Therefore the performance of an established Aspergillus-specific nested polymerase chain reaction assay (PCR) in CSF samples of immunocompromised patients with suspicion of CNS IA was evaluated. We identified 113 CSF samples from 55 immunocompromised patients for whom CNS aspergillosis was suspected. Of these patients 8/55 were identified as having proven/probable CNS IA while the remaining 47 patients were classified as having either possible (n = 22) or no CNS IA (n = 25). PCR positivity in CSF was observed for 8/8 proven/probable, in 4/22 possible CNS IA patients and in 2/25 NoIA patients yielding sensitivity and specificity values of 1.0 (95% CI 0.68–1) and 0.93 (95% CI 0.77–0.98) and a positive likelihood ratio of 14 and negative likelihood ratio of 0.0, respectively, thus resulting in a diagnostic odds ratio of ∞. The retrospective analysis of CSF samples from patients with suspected CNS IA yielded a high sensitivity of the nested PCR assay. PCR testing of CSF samples is recommended for patients for whom CNS IA is suspected, especially for those whose clinical condition does not allow invasive procedures as a positive PCR result makes the presence of CNS IA in that patient population highly likely.

[Central nervous system complications in patients undergoing cytotoxic chemotherapy and targeted therapies]

Anti-cancer treatments (cytotoxic chemotherapies, targeted therapies and hormonotherapies) are known to induce early and delayed neurological toxicities. Acute encephalopathies and posterior reversible encephalopathies are better known and described, physiopathological hypotheses are emerging. It is difficult to discriminate what drug is causing the symptoms in patients treated with multiple cytotoxic drugs. Methotrexate and ifosfamide are responsible for acute encephalopathies. L-asparaginase and methotrexate or targeted therapies may induce cerebrovascular complications. As life expectancy increases and more complex regimen including innovative targeted therapies are developed, new toxicity profiles can be expected. To be able to provide an early diagnosis, prevention, and treatment (when existing) of these pathologies remains a tremendous challenge that would allow a good quality of life with social and professional life after their cancer is cured.

CNS infections in patients with cancer

PURPOSE OF REVIEW

This article provides a practical clinical approach to potential CNS infections in patients with cancer, discusses problematic presentations of posterior reversible encephalopathy syndrome and immune reconstitution inflammatory syndrome, and includes specific testing and treatment recommendations for bacterial meningitis, invasive fungal infections, and opportunistic viral infections.

RECENT FINDINGS

The major deficits predisposing patients with cancer to CNS infection are neutropenia, barrier disruption, B-lymphocyte or immunoglobulin deficiency, and impaired T lymphocyte-mediated immunity. Evolving patterns of drug resistance and prophylactic antimicrobial regimens have altered the timing and range of organisms causing infections. Increasingly intensive immunosuppression has made new groups of patients vulnerable to infections such as progressive multifocal leukoencephalopathy. New MRI sequences offer the potential to diagnose such infections earlier, at a stage when they are more treatable.

SUMMARY

Despite improved prophylactic and therapeutic antibiotic regimens, CNS infections remain an important source of morbidity and mortality among several cancer patient groups, particularly those patients undergoing craniotomy and those with hematologic malignancies receiving either hematopoietic cell transplantation or other intensive chemotherapy regimens.

Viral encephalitis after allogeneic stem cell transplantation: a rare complication with distinct characteristics of different causative agents

BACKGROUND

Limited data are available on characteristics of viral encephalitis in patients after allogeneic stem cell transplantation.

DESIGN AND METHODS

We analyzed 2,628 patients after allogeneic stem cell transplantation to identify risk factors and characteristics of viral encephalitis.

RESULTS

Viral encephalitis occurred in 32 patients (1.2%, 95% confidence interval 0.8%-1.6%) and was associated with the use of OKT-3 or alemtuzumab for T-cell depletion (P < 0.001) and an increased mortality (P = 0.011) in comparison to patients without viral encephalitis. Detected viruses included human herpesvirus-6 (28%), Epstein-Barr virus (19%), herpes simplex virus (13%), JC virus (9%), varicella zoster virus (6%), cytomegalovirus (6%) and adenovirus (3%). More than one virus was identified in 16% of the patients. The median onset time was 106 days after allogeneic stem cell transplantation for the total group of 32 patients, but onset times were shortest in those with human herpesvirus-6 encephalitis and longest in those with JC virus-associated progressive multifocal leukoencephalopathy. The probability of a sustained response to treatment was 63% (95% confidence interval 44%-82%) with a median survival of 94 (95% confidence interval 36-152) days after onset, but significant variation was found when considering different causative viruses. Patients with herpes simplex virus encephalitis had the most favorable outcome with no encephalitis-related deaths.

CONCLUSIONS

The use of OKT-3 or alemtuzumab for in vivo T-cell depletion is associated with an increased risk of viral encephalitis after allogeneic stem cell transplantation. Different viruses are frequently associated with distinct characteristics such as onset time, response to treatment and outcome.