Central nervous system infections in the compromised host: a diagnostic approach

High prevalence of central nervous system cryptococcosis using a fingerprick whole-blood lateral flow assay in individuals with neurological symptoms and advanced HIV disease in a Brazilian emergency department

Timely diagnosis is key in managing central nervous system (CNS) cryptococcosis in people living with HIV/AIDS (PLWHA). There are few data on implementing fingerprick whole-blood cryptococcal antigen (CrAg) lateral flow assay (LFA) as the first test for diagnosing CNS cryptococcosis. We evaluated the prevalence of CNS cryptococcosis and cryptococcal antigenemia using fingerprick whole-blood in a referral emergency department (ED) in São Paulo, Brazil. This was a prospective cohort study of consecutive adult PLWHA with advanced HIV disease and neurological symptoms. Fingerprick whole-blood CrAg LFA was performed at bedside. Seventy-four individuals were enrolled (median age = 40 years; males = 62%). Prevalence of CNS cryptococcosis was 17.6% (13/74); 95% confidence interval (CI), 9.4-30.0%, and prevalence of positive fingerprick whole-blood CrAg LFA was 25.7% (19/74); 95% CI, 15.5-40.1%. Among the six (8.1%) patients with positive fingerprick whole-blood CrAg LFA and negative CSF CrAg LFA, four (5.4%) had isolated asymptomatic cryptococcal antigenemia, one (1.3%) had symptomatic cryptococcal antigenemia, and one (1.3%) had cryptococcemia. Prevalence of CNS cryptococcosis and cryptococcal antigenemia using fingerprick whole-blood CrAg LFA was high. Point-of-care testing was important for diagnosing CNS cryptococcosis in an ED from a middle-income country.

Role of Dectin-2 in the phagocytosis of Cryptococcus neoformans by dendritic cells

The cell walls and capsules of Cryptococcus neoformans, a yeast-type fungal pathogen, are rich in polysaccharides. Dectin-2 is a C-type lectin receptor (CLR) that recognizes high-mannose polysaccharides. Previously, we demonstrated that Dectin-2 is involved in cytokine production by bone marrow-derived dendritic cells (BM-DCs) in response to stimulation with C. neoformans. In the present study, we analyzed the role of Dectin-2 in the phagocytosis of C. neoformans by BM-DCs. The engulfment of this fungus by BM-DCs was significantly decreased in mice lacking Dectin-2 (Dectin-2KO) or caspase recruitment domain-containing protein 9 (CARD9KO), a common adapter molecule that delivers signals triggered by CLRs, compared to wild-type (WT) mice. Phagocytosis was likewise inhibited, to a similar degree, by the inhibition of Syk, a signaling molecule involved in CLR-triggered activation. A PI3K inhibitor, in contrast, completely abrogated the phagocytosis of C. neoformans. Actin polymerization, i.e., conformational changes in cytoskeletons detected at sites of contact with C. neoformans, was also decreased in BM-DCs of Dectin-2KO and CARD9KO mice. Finally, the engulfment of C. neoformans by macrophages was significantly decreased in the lungs of Dectin-2KO mice compared to WT mice. These results suggest that Dectin-2 may play an important role in the actin polymerization and phagocytosis of C. neoformans by DCs, possibly through signaling via CARD9 and a signaling pathway mediated by Syk and PI3K.

Disseminated Nocardiosis in a Renal Transplant Recipient

Nocardiosis is an uncommon opportunistic Gram-positive bacterial infection caused by aerobic actinomycetes in the genus Nocardia. Nocardia can cause localized or systemic suppurative diseases involving eyes, kidneys, skin, lungs, bone, and central nervous system. Disseminated nocardiosis is a rare condition, seen among immunocompromised patients. We report the case of a 55-year-old African American, kidney transplant male recipient on maintenance immunosuppression, who was diagnosed with cutaneous and pulmonary nocardiosis. Presenting symptoms were shortness of breath, and bilateral lower extremities pain and swelling. Tissue culture grew Gram-positive bacilli specified as Nocardia farcinica from thigh and gluteal abscesses. CT thorax showed bilateral reticulonodular opacities. The patient was managed with immunosuppression reduction and specific treatment with high-dose trimethoprim-sulfamethoxazole (TMP-SMX) in conjunction with linezolid. Combination antibiotics were continued for four weeks, and thereafter, TMP-SMX alone was continued for 12 months, at which point all lesions had healed. Nocardiosis with systemic involvement carries a poor prognosis. However, early diagnosis and appropriate antibiotic coverage had a favorable outcome in a renal transplant recipient. Recommended treatment duration is 6 to 12 months.

Limited Role of Mincle in the Host Defense against Infection with Cryptococcus deneoformans

Cryptococcus deneoformans is an opportunistic fungal pathogen that frequently causes fatal meningoencephalitis in patients with impaired cell-mediated immune responses such as AIDS. Caspase-associated recruitment domain 9 (CARD9) plays a critical role in the host defense against cryptococcal infection, suggesting the involvement of one or more C-type lectin receptors (CLRs). In the present study, we analyzed the role of macrophage-inducible C-type lectin (Mincle), one of the CLRs, in the host defense against C. deneoformans infection. Mincle expression in the lungs of wild-type (WT) mice was increased in the early stage of cryptococcal infection in a CARD9-dependent manner. In Mincle gene-disrupted (Mincle KO) mice, the clearance of this fungus, pathological findings, Th1/Th2 response, and antimicrobial peptide production in the infected lungs were nearly comparable to those in WT mice. However, the production of interleukin-22 (IL-22), tumor necrosis factor alpha (TNF-α), and IL-6 and the expression of AhR were significantly decreased in the lungs of Mincle KO mice compared to those of WT mice. In in vitro experiments, TNF-α production by bone marrow-derived dendritic cells was significantly decreased in Mincle KO mice. In addition, the disrupted lysates of C. deneoformans, but not those of whole yeast cells, activated Mincle-triggered signaling in an assay with a nuclear factor of activated T cells (NFAT)-green fluorescent protein (GFP) reporter cells expressing this receptor. These results suggest that Mincle may be involved in the production of Th22-related cytokines at the early stage of cryptococcal infection, although its role may be limited in the host defense against infection with C. deneoformans.

Reduction of Human DNA Contamination in Clinical Cerebrospinal Fluid Specimens Improves the Sensitivity of Metagenomic Next-Generation Sequencing

Metagenomics next-generation sequencing (mNGS) is increasingly available for the detection of obscure infectious diseases of the central nervous system. However, human DNA contamination from elevated white cells, one of the characteristic cerebrospinal fluid (CSF) features in meningitis patients, greatly reduces the sensitivity of mNGS in the pathogen detection. Currently, effective approaches to selectively reduce host DNA contamination from clinical CSF samples are still lacking. In this study, a total of 20 meningitis patients were enrolled, including 10 definitively diagnosed tuberculous meningitis (TBM) and 10 definite cryptococcal meningitis (CM) cases. To evaluate the effect of reduced human DNA in the sensitivity of mNGS detection, three specimen-processing protocols were performed: (i) To remove human DNA, saponin, a nonionic surfactant, was used to selectively lyse white cells in CSF followed by DNase treatment prior to the extraction of DNA; (ii) to reduce host DNA, CSF was centrifuged to remove human cells, and the supernatant was collected for DNA extraction; and (iii) DNA extraction from the unprocessed specimens was set as the control. We found that saponin processing significantly elevated the NGS unique reads for Cryptococcus (P < 0.01) compared with the control but had no effects for Mycobacterium tuberculosis (P > 0.05). However, detection of centrifuged supernatants improved the NGS unique reads for both TBM and CM compared with controls (P < 0.01). Our results demonstrate that the use of mNGS of centrifuged supernatants from clinical CSF samples in patients with TBM and CM is a simple and effective method to improve the sensitivity of pathogen detection.

Phosphatidylcholine PC ae C44:6 in cerebrospinal fluid is a sensitive biomarker for bacterial meningitis

Background

The timely diagnosis of bacterial meningitis is of utmost importance due to the need to institute antibiotic treatment as early as possible. Moreover, the differentiation from other causes of meningitis/encephalitis is critical because of differences in management such as the need for antiviral or immunosuppressive treatments. Considering our previously reported association between free membrane phospholipids in cerebrospinal fluid (CSF) and CNS involvement in neuroinfections we evaluated phosphatidylcholine PC ae C44:6, an integral constituent of cell membranes, as diagnostic biomarker for bacterial meningitis.

Methods

We used tandem mass spectrometry to measure concentrations of PC ae C44:6 in cell-free CSF samples (n = 221) from patients with acute bacterial meningitis, neuroborreliosis, viral meningitis/encephalitis (herpes simplex virus, varicella zoster virus, enteroviruses), autoimmune neuroinflammation (anti-NMDA-receptor autoimmune encephalitis, multiple sclerosis), facial nerve and segmental herpes zoster (shingles), and noninflammatory CNS disorders (Bell’s palsy, Tourette syndrome, normal pressure hydrocephalus).

Results

PC ae C44:6 concentrations were significantly higher in bacterial meningitis than in all other diagnostic groups, and were higher in patients with a classic bacterial meningitis pathogen (e.g. Streptococcus pneumoniae, Neisseria meningitidis, Staphylococcus aureus) than in those with less virulent or opportunistic pathogens as causative agents (P = 0.026). PC ae C44:6 concentrations were only moderately associated with CSF cell count (Spearman’s ρ = 0.45; P = 0.009), indicating that they do not merely reflect neuroinflammation. In receiver operating characteristic curve analysis, PC ae C44:6 equaled CSF cell count in the ability to distinguish bacterial meningitis from viral meningitis/encephalitis and autoimmune CNS disorders (AUC 0.93 both), but had higher sensitivity (91% vs. 41%) and negative predictive value (98% vs. 89%). A diagnostic algorithm comprising cell count, lactate and PC ae C44:6 had a sensitivity of 97% (specificity 87%) and negative predictive value of 99% (positive predictive value 61%) and correctly diagnosed three of four bacterial meningitis samples that were misclassified by cell count and lactate due to low values not suggestive of bacterial meningitis.

Conclusions

Increased CSF PC ae C44:6 concentrations in bacterial meningitis likely reflect ongoing CNS cell membrane stress or damage and have potential as additional, sensitive biomarker to diagnose bacterial meningitis in patients with less pronounced neuroinflammation.

Etiology, clinical presentation, outcome and the effect of initial management in immunocompromised patients with community acquired bacterial meningitis

OBJECTIVES

The aim was to analyze differences in clinical presentation, etiology, management, and outcome between immunocompromised and immunocompetent patients with acute bacterial meningitis (ABM).

METHODS

Data were extracted from 1056 adult ABM patients prospectively registered in the national Swedish quality register for ABM during 2008-2017. Primary endpoint was 30-day mortality and secondary endpoints 90-day mortality and unfavorable outcome.

RESULTS

An immunocompromised state was observed in 352 (33%) of the 1056 patients. Streptococcus pneumoniae dominated in both immunocompromised and immunocompetent patients (53% in both groups), whereas L monocytogenes occurred in 11% and 2%, respectively. The unadjusted odds ratio (OR) for 30-day mortality in immunocompromised compared to immunocompetent patients was 1.68 (95% confidence interval (CI): 1.07-2.63). Adjusted for age, sex, and mental status on admission the OR was 1.34 (CI: 0.82-2.21). Adjusted also for time to antibiotic treatment and corticosteroids the OR was 1.10 (CI: 0.59-2.05), and in patients without Listeria meningitis 0.98 (CI: 0.50-1.90). Although, the ORs were higher for 90-day mortality and unfavorable outcome the effects of adjustments were similar.

CONCLUSION

Mortality in immunocompromised patients with ABM is only moderately increased unless caused by Listeria. This difference is further reduced in patients given early antibiotic treatment and adjunctive corticosteroids.

FUNDING

This work was supported by Stockholm County Council.

Anastrozole-induced pulmonary cryptococcosis in a patient with early breast cancer: A case report

INTRODUCTION

Estrogen is a key factor in breast cancer carcinogenesis, and reductions in its synthesis can decrease breast cancer risk. Anastrozole can reduce plasma estrogen levels by inhibiting the enzyme aromatase, and is approved for adjuvant treatment of breast cancer. We report a case of pulmonary cryptococcosis in a patient who was treated with anastrozole for an early-stage tumor. This case is of special interest because the patient achieved a better curative effect after the administration of anastrozole was discontinued.

PATIENT CONCERNS

A 61-year-old woman was found to have multiple pulmonary nodules on chest computed tomography (CT) after being treated for 5 months with anastrozole as an adjuvant breast cancer therapy. A biopsy of the largest lesion of the right lung showed cryptococcus fungal bodies with granulomatous inflammation, so the patient was diagnosed with pulmonary cryptococcosis. She was treated with fluconazole (400 mg/day) for 1 month, but a follow-up CT scan of chest showed no improvement.

DIAGNOSIS

Pulmonary cryptococcosis.

INTERVENTIONS

Because the pulmonary cryptococcosis was not improving, the administration of anastrozole was discontinued. Fluconazole was continued.

OUTCOMES

The pulmonary lesions diminished in size 2 months after discontinuing anastrozole. The patient continued taking fluconazole for a total of 6 months without re-administration of anastrozole, and the lesions of pulmonary cryptococcosis almost disappeared.

CONCLUSION

This case of pulmonary cryptococcosis may have been induced by a decrease in estrogen level caused by the aromatase inhibitor, anastrozole. Treatment of pulmonary cryptococcosis with concurrent anastrozole use may be ineffective, and it may be better to discontinue the aromatase inhibitor.

Nocardiosis in Kidney Disease Patients under Immunosuppressive Therapy: Case Report and Literature Review

The increased use of novel and powerful immunosuppressive drugs in kidney diseases may concomitantly expose the patients to higher risk of opportunistic infections, some of which still remain underdiagnosed thus mishandled. As such, we recently had a less prepared encounter of pulmonary nocardial infection in an ANCA-associated renal vasculitis patient under steroid therapy. Despite the use of broad-spectrum antimicrobials including micafungin, the infection was still unbridled and eventually culminated in lethal brain abscess. We thus chose to renew the knowledge of the clinical features, imaging manifestations, differential diagnosis, specific laboratory tests and unique treatment about this rare infection in kidney diseases patients under immunosuppressive therapy. In addition, CT images of easily confused pulmonary lesions superimposed on kidney diseases were also retrieved from our depository. Moreover, impaired renal function as a risk factor for infection and pharmacological options for the treatment were also focused. By sharing our hard-learnt experience and reviewing the literatures, our report may contribute to the awareness among the clinicians in general and nephrologists in particular of this rare disease in susceptible patients and facilitate a swift thus life-saving treatment.

Recognition of Cryptococcus neoformans by Pattern Recognition Receptors and its Role in Host Defense to This Infection

Cryptococcus neoformans is a yeast-type opportunistic fungal pathogen with a capsule structure consisting of polysaccharides, such as glucuronoxylomannan and galactoxylomannan, and infects the lungs via an air-borne route. Most healthy individuals undergo asymptomatic infection with granulomatous lesions in the lungs caused by C. neoformans. However, immunocompromised hosts with severely impaired cellular immunity, such as those with acquired immune deficiency syndrome (AIDS), often suffer from disseminated infection into the central nervous system, leading to life-threatening meningoencephalitis. The recognition of pathogen-associated molecular patterns (PAMPs) by macrophages and dendritic cells plays an important role as the first line of host defense in the elimination of pathogens. Recently, numerous pattern recognition receptors (PRRs) that recognize these PAMPs have been identified. Also, the involvement of these PRRs, such as Toll-like receptors (TLRs), NOD-like receptors (NLRs), and C-type lectin receptors (CLRs), in cryptococcal infection has been analyzed. In particular, TLR9, NLR family pyrin domain-containing 3 (NLRP3), Dectin-2, mannose receptor (MR), and DC-SIGN have been found to recognize the DNA, cell wall components, intracellular polysaccharides, and mannoproteins, respectively. Future studies are expected to promote elucidation of the mechanisms of host immune response to C. neoformans, which will lead to the development of new vaccines and therapies for cryptococcal infection.

Central Nervous System Complications in Children Receiving Chemotherapy or Hematopoietic Stem Cell Transplantation

Therapy-related neurotoxicity greatly affects possibility of survival and quality of life of pediatric patients treated for cancer. Central nervous system (CNS) involvement is heterogeneous, varying from very mild and transient symptoms to extremely severe and debilitating, or even lethal syndromes. In this review, we will discuss the broad scenario of CNS complications and toxicities occurring during the treatment of pediatric patients receiving both chemotherapies and hematopoietic stem cell transplantation. Different types of complications are reviewed ranging from therapy related to cerebrovascular with a specific focus on neuroradiologic and clinical features.

Neurologic emergencies in HIV-negative immunosuppressed patients

HIV-negative immunosuppressed patients comprise a heterogeneous group including transplant patients, patients undergoing treatment with immunosuppressors, uremic patients, alcoholics, undernourished patients, diabetics, patients on dialysis, elderly patients, and those diagnosed with severe or neoplastic processes. Epileptic seizures, focal neurologic signs, and meningoencephalitis are neurologic syndromes that require urgent action. In most of these situations, neuroimaging tests are necessary, but the findings can be different from those observed in immunocompetent patients in function of the inflammatory response. Infectious disease is the first diagnostic suspicion, and the identification of an opportunistic pathogen should be oriented in function of the type and degree of immunosuppression. Other neurologic emergencies include ischemic stroke, cerebral hemorrhage, neoplastic processes, and pharmacological neurotoxicity. This article reviews the role of neuroimaging in HIV-negative immunodepressed patients with a neurologic complication that requires urgent management.

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.

State-of-the-Art Microbiologic Testing for Community-Acquired Meningitis and Encephalitis

Meningitis and encephalitis are potentially life-threatening diseases with a wide array of infectious, postinfectious, and noninfectious causes. Diagnostic testing is central to determining the underlying etiology, treatment, and prognosis, but many patients remain undiagnosed due to suboptimal testing and lack of tests for all pathogens. In this article, we summarize the epidemiology, barriers to diagnosis, and current best tests for meningitis and encephalitis in developed countries. We end with a brief discussion of new test methods, such as multiplex panel-based tests and metagenomic sequencing, which are likely to alter diagnostic strategies for these conditions in the near future.

Infections

"Children are not little adults," and while this is a well-worn aphorism, it is especially true in the context of infection, where the same organism may evoke a different immune response in the pediatric central nervous system (CNS) and clinical presentation may be clouded by the lack of a good history or paucity of clinical information. The chronology and natural history of different organisms/infections will be laid out together with the preferred use of different imaging modalities. This chapter will use illustrative examples of some of the more common infections and their complications, in addition to several more rare conditions as well as mimics of childhood CNS infection. Challenges in the imaging of children, including strategies to minimize the use of radiation, are discussed. Some of the more recently voiced concerns regarding the use of anesthetic agents in children are also addressed, along with the contrast agents that are typically required for imaging. With a global increase in worldwide travel the anticipation is that pediatricians will increasingly see unusual organisms presenting with CNS infection while dealing with the ever-present risk of drug resistance with inappropriately treated common or garden infections.

Cryptococcus neoformans Infection in Mice Lacking Type I Interferon Signaling Leads to Increased Fungal Clearance and IL-4-Dependent Mucin Production in the Lungs

Type I interferons (IFNs) are secreted by many cell types upon stimulation via pattern recognition receptors and bind to IFN-α/β receptor (IFNAR), which is composed of IFNAR1 and IFNAR2. Although type I IFNs are well known as anti-viral cytokines, limited information is available on their role during fungal infection. In the present study, we addressed this issue by examining the effect of IFNAR1 defects on the host defense response to Cryptococcus neoformans. In IFNAR1KO mice, the number of live colonies was lower and the host immune response mediated not only by Th1 but also by Th2 and Th17-related cytokines was more accelerated in the infected lungs than in WT mice. In addition, mucin production by bronchoepithelial cells and expression of MUC5AC, a major core protein of mucin in the lungs, were significantly higher in IFNAR1KO mice than in WT mice. This increase in mucin and MUC5AC production was significantly inhibited by treatment with neutralizing anti-IL-4 mAb. In contrast, administration of recombinant IFN-αA/D significantly suppressed the production of IL-4, but not of IFN-γ and IL-17A, in the lungs of WT mice after cryptococcal infection. These results indicate that defects of IFNAR1 led to improved clearance of infection with C. neoformans and enhanced synthesis of IFN-γ and the IL-4-dependent production of mucin. They also suggest that type I IFNs may be involved in the negative regulation of early host defense to this infection.

Vaccination recommendations and risk of meningitis following cochlear implantation

PURPOSE OF REVIEW

The Centers for Disease Control and Prevention has established vaccination guidelines for cochlear implant recipients to address the concern for implant-associated bacterial meningitis. Since their inception in 2002, these guidelines have undergone several revisions. We review the rationale and development of the current vaccination schedule.

RECENT FINDINGS

Bacterial meningitis is a rare yet potentially life-threatening complication of cochlear implantation. The recommendations for pneumococcal vaccination have evolved to a state in which nearly all cochlear implant patients receive a combination of both the PCV7 or PCV13 and PPSV23.

SUMMARY

Streptococcus pneumoniae vaccinations have dramatically decreased the incidence of serotype-specific invasive pneumococcal disease across all age groups. However, the optimal timing of immunization remains unclear in cochlear implant candidates.

Cryptococcal brainstem abscess mimicking brain tumors in an immunocompetent patient

Usually fungal infections caused by opportunistic and pathogenic fungi had been an important cause of morbidity and mortality among immunocompromised patients. However clinical data and investigations for immunocompetent pathogenic fungal infections had been rare and neglected into clinical studies. Especially Cryptococcal brainstem abscess cases mimicking brain tumors were also much more rare. So we report this unusual case. This 47-year-old man presented with a history of progressively worsening headache and nausea for 1 month and several days of vomituritions before admission. Neurological and laboratory examinations performed demonstrated no abnormal findings. Previously he was healthy and did not have any significant medical illnesses. A CT and MRI scan revealed enhancing 1.8×1.7×2.0 cm mass lesion in the left pons having central necrosis and peripheral edema compressing the fourth ventricle. And also positron emission tomogram scan demonstrated a hot uptake of fluoro-deoxy-glucose on the brainstem lesion without any evidences of systemic metastasis. Gross total mass resection was achieved with lateral suboccipital approach with neuronavigation system. Postoperatively he recovered without any neurological deficits. Pathologic report confirmed Cryptococcus neoformans and he was successively treated with antifungal medications. This is a previously unreported rare case of brainstem Cryptococcal abscess mimicking brain tumors in immunocompetent host without having any apparent typical meningeal symptoms and signs with resultant good neurosurgical recovery.

Chronic meningitis in systemic lupus erythematosus: An unusual etiology

Chronic aseptic meningitis is a rare manifestation of systemic lupus erythematosus (SLE). Apart from immunological causes and drugs, the aseptic meningitis group can include some unidentified viral infections that cannot be detected by routine microbiological testing. It is imperative to do complete cerebrospinal fluid (CSF) workup before implicating the symptoms to disease activity or drugs, as untreated infections cause significant mortality in SLE. We present a case of young female with SLE who presented with chronic meningitis of an uncommon etiology.

Dectin-2 deficiency promotes Th2 response and mucin production in the lungs after pulmonary infection with Cryptococcus neoformans

Dectin-2 is a C-type lectin receptor that recognizes high mannose polysaccharides. Cryptococcus neoformans, a yeast-form fungal pathogen, is rich in polysaccharides in its cell wall and capsule. In the present study, we analyzed the role of Dectin-2 in the host defense against C. neoformans infection. In Dectin-2 gene-disrupted (knockout) (Dectin-2KO) mice, the clearance of this fungus and the inflammatory response, as shown by histological analysis and accumulation of leukocytes in infected lungs, were comparable to those in wild-type (WT) mice. The production of type 2 helper T (Th2) cytokines in lungs was higher in Dectin-2KO mice than in WT mice after infection, whereas there was no difference in the levels of production of Th1, Th17, and proinflammatory cytokines between these mice. Mucin production was significantly increased in Dectin-2KO mice, and this increase was reversed by administration of anti-interleukin 4 (IL-4) monoclonal antibody (MAb). The levels of expression of β1-defensin, cathelicidin, surfactant protein A (Sp-A), and Sp-D in infected lungs were comparable between these mice. In in vitro experiments, IL-12p40 and tumor necrosis factor alpha (TNF-α) production and expression of CD86 and major histocompatibility complex (MHC) class II by bone marrow-derived dendritic cells and alveolar macrophages were completely abrogated in Dectin-2KO mice. Finally, the disrupted lysates of C. neoformans, but not of whole yeast cells, activated Dectin-2-triggered signaling in an assay with nuclear factor of activated T cells (NFAT)-green fluorescent protein (GFP) reporter cells expressing this receptor. These results suggest that Dectin-2 may oppose the Th2 response and IL-4-dependent mucin production in the lungs after infection with C. neoformans, and it may not be required for the production of Th1, Th17, and proinflammatory cytokines or for clearance of this fungal pathogen.

Validation of thwaites' diagnostic scoring system for the differential diagnosis of tuberculous meningitis and bacterial meningitis

To compare the clinical features of patients with tuberculous meningitis (TBM) and bacterial meningitis (BM) and to validate Thwaites' diagnostic scoring system for the differential diagnosis of TBM and BM, a retrospective review of 211 patients with TBM or BM who were admitted to Huashan Hospital, Fudan University, from 2007 to 2012 was conducted. The clinical characteristics and laboratory data were compared, and Thwaites' diagnostic scores were assessed at the time of admission for the differential diagnosis of TBM and BM. Significant differences were observed between the 2 groups in general information, clinical features, and cerebrospinal fluid characteristics. The sensitivity and specificity of Thwaites' diagnostic scoring system for the differential diagnosis of TBM and BM were found to be 98.2% and 43.6%, respectively, with positive and negative predictive values being 65.9% and 95.8%, respectively. The sensitivity and specificity for the differential diagnosis of TBM and initially treated BM were 98.2% and 82.9%, respectively, but were only 98.2% and 24.2% for that of TBM and partially treated BM, respectively. Thus, Thwaites' diagnostic scoring system was found to be highly effective for the differential diagnosis of TBM and initially treated BM but was found to be less effective for that of TBM and partially treated BM.

Bacterial brain abscess

Significant advances in the diagnosis and management of bacterial brain abscess over the past several decades have improved the expected outcome of a disease once regarded as invariably fatal. Despite this, intraparenchymal abscess continues to present a serious and potentially life-threatening condition. Brain abscess may result from traumatic brain injury, prior neurosurgical procedure, contiguous spread from a local source, or hematogenous spread of a systemic infection. In a significant proportion of cases, an etiology cannot be identified. Clinical presentation is highly variable and routine laboratory testing lacks sensitivity. As such, a high degree of clinical suspicion is necessary for prompt diagnosis and intervention. Computed tomography and magnetic resonance imaging offer a timely and sensitive method of assessing for abscess. Appearance of abscess on routine imaging lacks specificity and will not spare biopsy in cases where the clinical context does not unequivocally indicate infectious etiology. Current work with advanced imaging modalities may yield more accurate methods of differentiation of mass lesions in the brain. Management of abscess demands a multimodal approach. Surgical intervention and medical therapy are necessary in most cases. Prognosis of brain abscess has improved significantly in the recent decades although close follow-up is required, given the potential for long-term sequelae and a risk of recurrence.

Bacillus cereus bacteremia and multiple brain abscesses during acute lymphoblastic leukemia induction therapy

Bacillus cereus can cause serious infections in immunosuppressed patients. This population may be susceptible to B. cereus pneumonia, bacteremia, cellulitis, and rarely cerebral abscess. Here we report an 8-year-old boy undergoing induction therapy for acute lymphoblastic leukemia who developed multifocal B. cereus cerebral abscesses, highlighting the propensity for B. cereus to develop cerebral abscesses. A review of the literature over the past 25 years identified another 11 cases (3 children and 8 adults) of B. cereus cerebral abscess in patients undergoing cancer therapy. B. cereus cerebral abscesses were associated with a high mortality rate (42%) and significant morbidity. Notably, B. cereus bacteremia with concomitant cerebral abscess was associated with induction chemotherapy for acute leukemia in both children and adults (10 of 12 case reports). Our case report and review of the literature highlights the propensity for B. cereus to develop cerebral abscess(es). Therefore, early consideration for neuroimaging should be given for any neutropenic cancer patient identified with B. cereus bacteremia, in particular those with acute leukemia during induction therapy.

Defect of CARD9 leads to impaired accumulation of gamma interferon-producing memory phenotype T cells in lungs and increased susceptibility to pulmonary infection with Cryptococcus neoformans

Caspase recruitment domain-containing protein 9 (CARD9) is an adaptor molecule signal that is critical for NF-κB activation and is triggered through C-type lectin receptors (CLRs), which are pattern recognition receptors that recognize carbohydrate structures. Previous studies have reported that Cryptococcus neoformans, a fungal pathogen that causes meningoencephalitis in AIDS patients, is recognized through some CLRs, such as mannose receptors or DC-SIGN. However, the role of CARD9 in the host defense against cryptococcal infection remains to be elucidated. In the present study, we analyzed the role of CARD9 in the host defense against pulmonary infection with C. neoformans. CARD9 gene-disrupted (knockout [KO]) mice were highly susceptible to this infection, as shown by the reduced fungal clearance in the infected lungs of CARD9 KO mice, compared to that in wild-type (WT) mice. Gamma interferon (IFN-γ) production was strongly reduced in CARD9 KO mice during the innate-immunity phase of infection. Reduced IFN-γ synthesis was due to impaired accumulation of NK and memory phenotype T cells, which are major sources of IFN-γ innate-immunity-phase production; a reduction in the accumulation of these cells was correlated with reduced CCL4, CCL5, CXCL9, and CXCL10 synthesis. However, differentiation of Th17 cells, but not of Th1 cells, was impaired at the adaptive-immunity phase in CARD9 KO mice compared to WT mice, although there was no significant difference in the infection susceptibility between interleukin 17A (IL-17A) KO and WT mice. These results suggest that CARD9 KO mice are susceptible to C. neoformans infection probably due to the reduced accumulation of IFN-γ-expressing NK and memory phenotype T cells at the early stage of infection.

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.

Neurologic complications in renal transplantation

Neurologic complications following kidney transplant are more common than in the general population with the reported incidence around 10-21%. Need for multiple drugs, decreased cellular immunity, accelerated atherosclerotic disease, and frequency of metabolic abnormalities are the most common predisposing factors for neurologic abnormalities. Neurologic side-effects of calcineurin inhibitors range from mild tremors to paraplegia or posterior reversible encephalopathy syndrome (PRES) and are generally reversible by lowering the dose or complete discontinuation of the drug when possible. Clinical presentation of central nervous system infection in transplant recipients can be different from the normal population as the anti-inflammatory effects of immunosuppressive therapy may obscure signs of meningeal inflammation and changes in the level of consciousness may be subtle. Bacterial infections remain the most common infections but unusual pathogens figure prominently in the differential diagnosis. The most frequent malignancies of the brain are lymphomas and metastatic tumors which are for the most part, de novo malignancies from immunosuppression. Decreasing immunosuppression is almost always a part of treating malignancy. The prevalence of stroke is reported to be around 8% with age>40 years, diabetic nephropathy as the underlying cause of end-stage kidney disease, and peripheral vascular disease being the strongest predictors.

Intracavernous internal carotid artery mycotic aneurysms: comprehensive review and evaluation of the role of endovascular treatment

Mycotic aneurysms may arise in the setting of many local or systemic infections. Those of the intracranial circulation are especially worrisome due to their potential to compress vital neural structures and their propensity for rupture with consequent hemorrhage. Mycotic aneurysms of the intracavernous internal carotid artery (ICA) represent an exceedingly rare clinical entity, described in less than fifty published cases. Typically presenting as a cavernous sinus syndrome with signs and symptoms of the underlying infection, they are often missed initially, with diagnosis and treatment commencing for the triggering infection or confused with cavernous sinus thrombophlebitis, which may be additionally coexistent, confounding timely diagnosis of the aneurysmal disease. Compared to non-mycotic aneurysms of the intracavernous ICA, which typically have a benign course, the infectious etiology of the mycotic variety increases their tendency to rupture, precludes surgical clipping as a viable treatment option, and requires institution of prolonged antibiotic therapy prior to definitive intervention. Their critical location, friability, and propensity to occur bilaterally result in an unpredictable risk of rapid neurological decline and death, making the timing and specific nature of treatment a unique dilemma facing the treating physician. This review seeks to discuss the natural history of and management strategies for mycotic aneurysms of the intracavernous ICA with special emphasis on the role, safety, and efficacy of endovascular therapies.

Comparison of clinical features in patients with persistent and nonpersistent cryptococcal meningitis: twelve years of clinical experience in four centers in China

BACKGROUND AND AIMS

Cryptococcal meningitis (CM) has gradually increased in the recent 20 years in the whole world. Although the mortality decreased significantly in recent years, it was still high, especially in patients with persistent infection. Therefore, we compare differences of clinical features between persistent and nonpersistent CM patients.

METHODS

We conducted a retrospective review of medical records of patients diagnosed with CM from January 2000 to December 2011 in four centers in China, including demographic features, underlying diseases, clinical presentations, laboratory data, and so on.

RESULTS

Of 106 CM patients enrolled, 16 were identified as persistent cases. Among all variables, persistent CM patients were more like to be human immunodeficiency viruses (HIV) infection (P < 0.05), stiff neck (P < 0.01), a serum hemoglobin < 90 g/L (P < 0.01), a serum potassium concentration <2.7 mg/L (P < 0.01), an intracranial pressure (ICP) >400 mmH2 O (P < 0.01), and a latex agglutination cryptococcal antigen titer of cerebrospinal fluid (CSF LACT) >1:1024 (P < 0.01) than nonpersistent ones. A multivariate analysis showed that HIV infection (OR 7.49), stiff neck (OR 11.7), a serum potassium <2.7 mmol/L (OR 9.45), and an ICP >400 mmH2 O (OR 6.83) were closely correlated with persistent CM.

CONCLUSIONS

Although it is difficult to deal with persistent CM nowadays, some cases could be predicted early enough in the future, so as to be treated appropriately and have relatively good outcomes.

The clinical and laboratory diagnosis of acute meningitis and acute encephalitis

INTRODUCTION

Acute bacterial meningitis (ABM) is a life-threatening infectious disease requiring prompt antimicrobial therapy. ABM must be differentiated from systemic disorders with CNS manifestations that may mimic ABM. ABM should also be differentiated from acute meningoencephalitis (AME) and acute viral encephalitis (AVE). Nonviral causes of AME are treatable. Among the causes of AVE, Herpes simplex encephalitis (HSE) is treatable. This article reviews the clinical diagnostic approach to ABM, AME and AVE.

AREAS COVERED

The differential diagnostic (DDx) approach to ABM, AME and AVE is based on clinical and laboratory findings. A specific pathogen diagnosis is based on serum/cerebrospinal fluid (CSF) tests. This overview presents the diagnostic approach to ABM, AME and AVE in normal hosts (excluding brain abscesses and chronic CNS infections).

EXPERT OPINION

It is time critical to diagnose ABM and begin empiric antimicrobial therapy based on the known/most likely pathogen. The diagnosis of ABM depends on clinical features and the CSF profile. The CSF Gram stain and CSF lactic acid (LA) levels provide the most rapid, reliable and cost-effective tests to diagnose ABM. CSF LA levels are also the best way to diagnose partially treated acute bacterial meningitis (PTABM). In those cases of AME/AVE due to viruses with a CSF profile mimicking ABM, for example, HSE, unelevated CSF LA levels rapidly/reliably rule out ABM as a diagnostic possibility.

Central Nervous System Infections

Central nervous system (CNS) infections—i.e., infections involving the brain (cerebrum and cerebellum), spinal cord, optic nerves, and their covering membranes—are medical emergencies that are associated with substantial morbidity, mortality, or long-term sequelae that may have catastrophic implications for the quality of life of affected individuals. Acute CNS infections that warrant neurointensive care (ICU) admission fall broadly into three categories—meningitis, encephalitis, and abscesses—and generally result from blood-borne spread of the respective microorganisms. Other causes of CNS infections include head trauma resulting in fractures at the base of the skull or the cribriform plate that can lead to an opening between the CNS and the sinuses, mastoid, the middle ear, or the nasopharynx. Extrinsic contamination of the CNS can occur intraoperatively during neurosurgical procedures. Also, implanted medical devices or adjunct hardware (e.g., shunts, ventriculostomies, or external drainage tubes) and congenital malformations (e.g., spina bifida or sinus tracts) can become colonized and serve as sources or foci of infection. Viruses, such as rabies, herpes simplex virus, or polioviruses, can spread to the CNS via intraneural pathways resulting in encephalitis. If infection occurs at sites (e.g., middle ear or mastoid) contiguous with the CNS, infection may spread directly into the CNS causing brain abscesses; alternatively, the organism may reach the CNS indirectly via venous drainage or the sheaths of cranial and spinal nerves. Abscesses also may become localized in the subdural or epidural spaces. Meningitis results if bacteria spread directly from an abscess to the subarachnoid space. CNS abscesses may be a result of pyogenic meningitis or from septic emboli associated with endocarditis, lung abscess, or other serious purulent infections. Breaches of the blood–brain barrier (BBB) can result in CNS infections. Causes of such breaches include damage (e.g., microhemorrhage or necrosis of surrounding tissue) to the BBB; mechanical obstruction of microvessels by parasitized red blood cells, leukocytes, or platelets; overproduction of cytokines that degrade tight junction proteins; or microbe-specific interactions with the BBB that facilitate transcellular passage of the microorganism. The microorganisms that cause CNS infections include a wide range of bacteria, mycobacteria, yeasts, fungi, viruses, spirochaetes (e.g., neurosyphilis), and parasites (e.g., cerebral malaria and strongyloidiasis). The clinical picture of the various infections can be nonspecific or characterized by distinct, recognizable clinical syndromes. At some juncture, individuals with severe acute CNS infections require critical care management that warrants neuro-ICU admission. The implications for CNS infections are serious and complex and include the increased human and material resources necessary to manage very sick patients, the difficulties in triaging patients with vague or mild symptoms, and ascertaining the precise cause and degree of CNS involvement at the time of admission to the neuro-ICU. This chapter addresses a wide range of severe CNS infections that are better managed in the neuro-ICU. Topics covered include the medical epidemiology of the respective CNS infection; discussions of the relevant neuroanatomy and blood supply (essential for understanding the pathogenesis of CNS infections) and pathophysiology; symptoms and signs; diagnostic procedures, including essential neuroimaging studies; therapeutic options, including empirical therapy where indicated; and the perennial issue of the utility and effectiveness of steroid therapy for certain CNS infections. Finally, therapeutic options and alternatives are discussed, including the choices of antimicrobial agents best able to cross the BBB, supportive therapy, and prognosis.

Laboratory diagnosis of CNS infections by molecular amplification techniques

The initial presentation of symptoms and clinical manifestations of CNS infectious diseases often makes a specific diagnosis difficult and uncertain, and the emergence of polymerase chain reaction-led molecular techniques have been used in improving organism-specific diagnosis. These techniques have not only provided rapid, non-invasive detection of microorganisms causing CNS infections, but also demonstrated several neurologic disorders linked to infectious pathogens. Molecular methods performed on cerebrospinal fluid are recognized as the new 'gold standard' for some of these infections caused by microorganisms that are difficult to detect and identify. Although molecular techniques are predicted to be widely used in diagnosing and monitoring CNS infections, the limitations as well as strengths of these techniques must be clearly understood by both clinicians and laboratory personnel.

Systemic lupus erythematosus (SLE) cerebritis versus Listeria monocytogenes meningoencephalitis in a patient with systemic lupus erythematosus on chronic corticosteroid therapy: the diagnostic importance of cerebrospinal fluid (CSF) of lactic acid levels

BACKGROUND

Listeria monocytogenes is a motile, aerobic, Gram-positive intracellular bacillus that causes enteritis, meningitis, meningoencephalitis, or subacute bacterial endocarditis. Patients with impaired T-lymphocyte function/cell-mediated immunity are predisposed to intracellular pathogens, e.g., L. monocytogenes. In adults, infection by L. monocytogenes of the central nervous system (CNS) clinically manifests as either acute bacterial meningitis or meningoencephalitis. In patients with systemic lupus erythematosus (SLE) presenting with headache and fever, SLE cerebritis must be differentiated from acute bacterial meningitis by lumbar puncture and cerebrospinal fluid (CSF) analysis. Neuropathogenic viruses are the most common causes of meningoencephalitis. The most rapid and accurate way to differentiate bacterial meningoencephalitis from nonbacterial meningoencephalitis is CSF lactic acid levels.

METHODS

We present a patient receiving chronic corticosteroid therapy and manifesting SLE and severe L. monocytogenes meningoencephalitis. An early diagnosis of L. meningoencephalitis was achieved by demonstrating a very highly elevated level of lactic acid in his CSF, days before CSF and blood cultures tested positive for L. monocytogenes.

RESULTS AND CONCLUSION

In this patient, the highly elevated levels of lactic acid in his CSF ruled out both viral meningoencephalitis and SLE cerebritis. The case was complicated by communicating hydrocephalus, and the patient later underwent placement of a shunt. He completed 6 weeks of meningeal dosed ampicillin.

Cryptococcus neoformans suppresses the activation of bone marrow-derived dendritic cells stimulated with its own DNA, but not with DNA from other fungi

DNA from Cryptococcus neoformans activates bone marrow-derived dendritic cells (BM-DCs) in a TLR9-dependent manner. In this study, we examined the effect of the culture supernatants of C. neoformans on the activation of BM-DCs caused by its own DNA. C. neoformans supernatants suppressed IL-12p40, IL-6 production and CD40 expression by BM-DCs stimulated with its own DNA, but not with CpG-ODN and DNA from Candida albicans, Saccharomyces cerevisiae or Escherichia coli. In a confocal microscopic analysis, C. neoformans DNA was colocalized with LAMP-1, a late endosomal marker, and TLR9. The culture supernatants did not show any apparent suppression of these responses. In a luciferase reporter assay, C. neoformans supernatants inhibited NFκB activation caused by its own DNA. These inhibitory activities were attenuated by treatment with heat or trypsin. These results indicate that C. neoformans secrete certain proteinous molecules that suppress the activation of BM-DCs caused by its own DNA.

Central nervous system infections as a cause of an altered mental status? What is the pathogen growing in your central nervous system?

There are several central nervous system (CNS) infections (meningitis, encephalitis, and brain abscess), any of which may present with an altered level of consciousness. Because CNS infections can have a devastating outcome, it is important to recognize the presence of a CNS infection and begin treatment as soon as possible because early appropriate therapy may, in some cases, limit morbidity and mortality.

Toll-like receptor stimulation enhances phagocytosis and intracellular killing of nonencapsulated and encapsulated Streptococcus pneumoniae by murine microglia

Toll-like receptors (TLRs) are crucial pattern recognition receptors in innate immunity that are expressed in microglia, the resident macrophages of the brain. TLR2, -4, and -9 are important in the responses against Streptococcus pneumoniae, the most common agent causing bacterial meningitis beyond the neonatal period. Murine microglial cultures were stimulated with agonists for TLR1/2 (Pam(3)CSK(4)), TLR4 (lipopolysaccharide), and TLR9 (CpG oligodeoxynucleotide) for 24 h and then exposed to either the encapsulated D39 (serotype 2) or the nonencapsulated R6 strain of S. pneumoniae. After stimulation, the levels of interleukin-6 and CCL5 (RANTES [regulated upon activation normal T-cell expressed and secreted]) were increased, confirming microglial activation. The TLR1/2, -4, and -9 agonist-stimulated microglia ingested significantly more bacteria than unstimulated cells (P < 0.05). The presence of cytochalasin D, an inhibitor of actin polymerizaton, blocked >90% of phagocytosis. Along with an increased phagocytic activity, the intracellular bacterial killing was also increased in TLR-stimulated cells compared to unstimulated cells. Together, our data suggest that microglial stimulation by these TLRs may increase the resistance of the brain against pneumococcal infections.

Detection of Aspergillus DNA by a nested PCR assay is able to improve the diagnosis of invasive aspergillosis in paediatric patients

Fungal infections are a leading cause of morbidity and mortality in severely immunocompromised patients and have been increasing in incidence in recent years. Invasive aspergillosis (IA) is the most common filamentous fungal infection and is, in adults as well as in children, difficult to diagnose. Several PCR assays to detect Aspergillus DNA have been established, but so far, studies on molecular tools for the diagnosis of IA in children are few. We evaluated the results of a nested PCR assay to detect Aspergillus DNA in clinical samples from paediatric and adolescent patients with suspected IA. Blood and non-blood samples from immunocompromised paediatric and adolescent patients with suspected invasive fungal infection were sent for processing Aspergillus PCR to our laboratory. PCR results from consecutive patients from three university children's hospitals investigated between November 2000 and January 2007 were evaluated. Fungal infections were classified according to the EORTC classification on the grounds of clinical findings, microbiology and radio-imaging results. Two hundred and ninety-one samples from 71 patients were investigated for the presence of Aspergillus DNA by our previously described nested PCR assay. Two, 3 and 34 patients had proven, probable and possible IA, respectively. Sensitivity (calculated from proven and probable patients, n=5) and specificity (calculated from patients without IA, n=32) rates of the PCR assay were 80 and 81 %, respectively. Our nested PCR assay was able to detect Aspergillus DNA in blood, cerebrospinal fluid and bronchoalveolar lavage samples from paediatric and adolescent patients with IA with high sensitivity and specificity rates.

Approach to the immunocompromised host with infection in the intensive care unit

Despite significant advances in the prevention, diagnosis, and treatment of infection in the immunocompromised host, it remains a major cause of morbidity, increased length of stay, total costs, and of course mortality. Intensive care mortality rates are significantly higher among immunocompromised hosts in part due to the higher incidence of infection severity. The superimposition of the compromised host defenses and critical illness makes the detection and management of infections in such patients more difficult, but crucial toward salvaging patient outcome. Moreover, although there is a rapidly increasing evidence base in intensive care medicine, many interventional trials for the management of severe sepsis (activated protein C, adjunctive corticosteroids, goal-based resuscitation), acute lung injury (low stretch ventilation), and other organ failures have excluded immunocompromised hosts.

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

Infections of the central nervous system (CNS) are increasingly reported in patients with malignancies. Heavily immunocompromised patients like those after allogeneic stem cell transplantation (SCT) or previous T cell depleting treatment regimens (e.g. with fludarabine or alemtuzumab) are at highest risk for cerebral infections. The spectrum of causative organisms may vary greatly, depending on the underlying malignancy, its treatment and various other factors. Toxoplasma gondii and fungi are the leading causative organisms in patients after allogeneic SCT, but also viruses such as herpes simplex virus or JC virus may be detected in these patients. Definitive diagnosis of cerebral infection still remains a high challenge, although diagnostics have improved by the wide availability of imaging techniques and polymerase chain reaction in recent years. Novel therapeutic options are arising, particularly for fungal CNS infections. Here, we summarise aspects on epidemiology, clinical symptoms and prognosis of CNS infections in patients with malignancies. Additionally, we give an overview on the diagnostics and management of cerebral infections in these patients including evidence evaluation of efficacy of treatment.

Intracranial lesions mimicking neoplasms

CONTEXT

A broad spectrum of nonneoplastic conditions can mimic a brain tumor, both clinically and radiologically. In this review we consider these, taking into consideration the following etiologic categories: infection, demyelination, vascular diseases, noninfectious inflammatory disorders, and iatrogenic conditions. We give an overview of such diseases, which represent a potential pitfall for pathologists and other clinicians involved in patient care, and present selected cases from each category.

OBJECTIVE

To illustrate the radiologic and pathologic features of nontumoral intracranial lesions that can clinically and radiologically mimic neoplasia.

DATA SOURCES

Case-derived material and literature review.

CONCLUSIONS

A variety of nonneoplastic lesions can present clinically and radiologically as primary or metastatic central nervous system tumors and result in surgical biopsy or resection of the lesion. In such situations, the pathologist has an important role to play in correctly determining the nature of these lesions. Awareness of the entities that can present in this way will assist the pathologist in the correct diagnosis of these lesions.

Solitary ring enhancing brain lesion in a patient with AIDS

Toxoplasmosis in immune competent patients usually causes asymptomatic infection or mild symptoms, while in immunocompromised and AIDS patients it can be a life threatening condition. We report a case of cerebral toxoplasmosis in a patient with AIDS and review the causes of brain ring enhancing lesions.