Quantification of brain voriconazole levels in healthy adults using fluorine magnetic resonance spectroscopy

A rare case of cerebral phaeohyphomycosis caused by Fonsecaea species in a renal transplant patient

Cerebral phaeohyphomycosis (CP) is a serious form of phaeohyphomycosis. We report a case of CP caused by Fonsecaea species in a 66-year-old immunocompromised renal transplant recipient female. Craniotomy was performed on an irregularly enhancing right cerebellar hemisphere lesion and abscess and tissue samples collected for microbiological and histological evaluation, showing fungal elements and Fonsecaea species was isolated. Antifungal treatment with voriconazole & liposomal amphotericin B was initiated with a temporary improvement in the patient's condition. Deep vein thrombosis jeopardized patient's prognosis. Despite aggressive surgical and medical intervention, our patient succumbed to the disease. Historically, CP has been linked with fatality rates as high as 65 %, despite surgical intervention and systemic antifungal medication.

Chronic Granulomatous Invasive Fungal Sinusitis in Patients With Immunocompetence: A Review

OBJECTIVE

We aimed to study the literature on chronic granulomatous invasive fungal sinusitis to elucidate the changing trends in the management of the disease.

DATA SOURCES

Using specific keywords, we searched the PubMed, PubMed Central, and Scopus databases over the past 50 years, which yielded 938 articles in the English language.

REVIEW METHODS

Scrutiny of 147 relevant articles revealed 15 homogenous case series (255 cases of histologically proven chronic granulomatous fungal sinusitis alone) and 8 heterogeneous case series (patients with other types of fungal sinusitis included), which were analyzed in detail (all with >5 cases each).

CONCLUSIONS

The disease typically affected middle-aged adults with immunocompetence. Most reports were from Sudan, India, and Saudi Arabia. A slowly progressive orbital, cheek, or palatal mass with proptosis (88.2%) or sinonasal symptoms (39.2%) was typical. Ethmoid (57.2%) and maxillary (51.4%) sinuses were chiefly affected with intracranial extension in 35.1%. Aspergillus flavus (64%) was the most frequent isolate reported. Endoscopic excision (78.8%) followed by azole therapy was the preferred treatment in recent reports. Orbital exenteration and craniotomy were infrequently performed. Complete resolution or improvement was reported in 91.3% of patients. Mortality ranged from 5.9% to 22.2%. There is a trend in the literature toward less radical and disfiguring surgery and preferential use of azoles, with good outcomes even in advanced cases.

IMPLICATIONS FOR PRACTICE

Chronic granulomatous fungal sinusitis should be diagnosed on the basis of well-defined histopathologic features. A combination of endoscopic sinus surgery and azole therapy usually yields good outcomes.

Blastomycosis: A Review of Mycological and Clinical Aspects

Blastomycosis is caused by a thermally dimorphic fungus that thrives in moist acidic soil. Blastomyces dermatitidis is the species responsible for most infections in North America and is especially common in areas around the Great Lakes, the St. Lawrence Seaway, and in several south-central and southeastern United States. Other Blastomyces species have more recently been discovered to cause disease in distinct geographic regions around the world. Infection almost always occurs following inhalation of conidia produced in the mold phase. Acute pulmonary infection ranges from asymptomatic to typical community-acquired pneumonia; more chronic forms of pulmonary infection can present as mass-like lesions or cavitary pneumonia. Infrequently, pulmonary infection can progress to acute respiratory distress syndrome that is associated with a high mortality rate. After initial pulmonary infection, hematogenous dissemination of the yeast form of Blastomyces is common. Most often this is manifested by cutaneous lesions, but osteoarticular, genitourinary, and central nervous system (CNS) involvement also occurs. The diagnosis of blastomycosis can be made by growth of the mold phase of Blastomyces spp. in culture or by histopathological identification of the distinctive features of the yeast form in tissues. Detection of cell wall antigens of Blastomyces in urine or serum provides a rapid method for a probable diagnosis of blastomycosis, but cross-reactivity with other endemic mycoses commonly occurs. Treatment of severe pulmonary or disseminated blastomycosis and CNS blastomycosis initially is with a lipid formulation of amphotericin B. After improvement, therapy can be changed to an oral azole, almost always itraconazole. With mild to moderate pulmonary or disseminated blastomycosis, oral itraconazole treatment is recommended.

First in vivo fluorine-19 magnetic resonance imaging of the multiple sclerosis drug siponimod

Theranostic imaging methods could greatly enhance our understanding of the distribution of CNS-acting drugs in individual patients. Fluorine-19 magnetic resonance imaging (¹⁹F MRI) offers the opportunity to localize and quantify fluorinated drugs non-invasively, without modifications and without the application of ionizing or other harmful radiation. Here we investigated siponimod, a sphingosine 1-phosphate (S₁P) receptor antagonist indicated for secondary progressive multiple sclerosis (SPMS), to determine the feasibility of in vivo ¹⁹F MR imaging of a disease modifying drug. Methods: The ¹⁹F MR properties of siponimod were characterized using spectroscopic techniques. Four MRI methods were investigated to determine which was the most sensitive for ¹⁹F MR imaging of siponimod under biological conditions. We subsequently administered siponimod orally to 6 mice and acquired ¹⁹F MR spectra and images in vivo directly after administration, and in ex vivo tissues. Results: The ¹⁹F transverse relaxation time of siponimod was 381 ms when dissolved in dimethyl sulfoxide, and substantially reduced to 5 ms when combined with serum, and to 20 ms in ex vivo liver tissue. Ultrashort echo time (UTE) imaging was determined to be the most sensitive MRI technique for imaging siponimod in a biological context and was used to map the drug in vivo in the stomach and liver. Ex vivo images in the liver and brain showed an inhomogeneous distribution of siponimod in both organs. In the brain, siponimod accumulated predominantly in the cerebrum but not the cerebellum. No secondary ¹⁹F signals were detected from metabolites. From a translational perspective, we found that acquisitions done on a 3.0 T clinical MR scanner were 2.75 times more sensitive than acquisitions performed on a preclinical 9.4 T MR setup when taking changes in brain size across species into consideration and using equivalent relative spatial resolution. Conclusion: Siponimod can be imaged non-invasively using ¹⁹F UTE MRI in the form administered to MS patients, without modification. This study lays the groundwork for more extensive preclinical and clinical investigations. With the necessary technical development, ¹⁹F MRI has the potential to become a powerful theranostic tool for studying the time-course and distribution of CNS-acting drugs within the brain, especially during pathology.

[Clinical Analysis of Voriconazole Concentrations in Cerebrospinal Fluid and Blood in Patients with Ryptococcal Meningitis]

Objective

To investigate the concentrations of voriconazole (VCZ) in the central nervous system (CNS) of patients with cryptococcal meningitis and the relationship thereof.

Methods

We retrospectively analyzed the trough concentration of VCZ in the cerebrospinal fluid (CSF) and the blood of 25 adult patients who had cryptococcal meningitis, and who were not infected with HIV. We also examined patient-level characteristics that could contribute to the differences in CSF/plasma VCZ concentration ratio.

Results

The trough concentration of VCZ in plasma ranged from 0.38 to 8.56 mg/L, and the median (P 25, P 75) was 1.81 (1.40, 3.84) mg/L. The trough concentration of VCZ in CSF ranged from 0.17 to 3.92 mg/L, and the median (P 25, P 75) was 1.02 (0.54, 1.84) mg/L. The CSF VCZ trough concentration showed a slight negative correlation with the nucleated cell counts in CSF, but the correlation was not statistically significant ( r=-0.377, P=0.063). There was a positive correlation between VCZ concentrations in CSF and that in the plasma ( r=0.736, P<0.001), and the median (P 25, P 75) CSF/plasma ratio was 0.43 (0.34, 0.68). The CSF/plasma ratio did not statistically correlate with age, body surface area (BSA), radiology changes (hydrocephalus), or intracranial pressure.

Conclusion

There is a positive correlation between VCZ concentration in CSF and VCZ concentration in the plasma, and no influencing factors of CSF/plasma ratio were found.

Cerebral mucormycosis: intranasal route to deliver amphotericin B for effective management?

As cerebral mucormycosis is devastating in nature, here we discuss possible use of the intranasal route, in comparison to or in addition to intravenous administration, as a therapeutic approach to manage cases of mucormycosis with central nervous system involvement.

Consensus guidelines for optimising antifungal drug delivery and monitoring to avoid toxicity and improve outcomes in patients with haematological malignancy and haemopoietic stem cell transplant recipients, 2021

Antifungal agents can have complex dosing and the potential for drug interaction, both of which can lead to subtherapeutic antifungal drug concentrations and poorer clinical outcomes for patients with haematological malignancy and haemopoietic stem cell transplant recipients. Antifungal agents can also be associated with significant toxicities when drug concentrations are too high. Suboptimal dosing can be minimised by clinical assessment, laboratory monitoring, avoidance of interacting drugs, and dose modification. Therapeutic drug monitoring (TDM) plays an increasingly important role in antifungal therapy, particularly for antifungal agents that have an established exposure-response relationship with either a narrow therapeutic window, large dose-exposure variability, cytochrome P450 gene polymorphism affecting drug metabolism, the presence of antifungal drug interactions or unexpected toxicity, and/or concerns for non-compliance or inadequate absorption of oral antifungals. These guidelines provide recommendations on antifungal drug monitoring and TDM-guided dosing adjustment for selected antifungal agents, and include suggested resources for identifying and analysing antifungal drug interactions. Recommended competencies for optimal interpretation of antifungal TDM and dose recommendations are also provided.

Antifungal drugs: An updated review of central nervous system pharmacokinetics

Invasive fungal infections (IFIs) in the central nervous system (CNS) are particularly hard to treat and are associated with high morbidity and mortality rates. Four chemical classes of systemic antifungal agents are used for the treatment of IFIs (eg meningitis), including polyenes, triazoles, pyrimidine analogues and echinocandins. This review will address all of these classes and discuss their penetration and accumulation in the CNS. Treatment of fungal meningitis is based on the antifungal that shows good penetration and accumulation in the CNS. Pharmacokinetic data concerning the entry of antifungal agents into the intracranial compartments are faulty. This review will provide an overview of the ability of systemic antifungals to penetrate the CNS, based on previously published drug physicochemical properties and pharmacokinetic data, for evaluation of the most promising antifungal drugs for the treatment of fungal CNS infections. The studies selected and discussed in this review are from 1990 to 2019.

Anti-infective treatment of brain abscess

INTRODUCTION

Brain abscess is an uncommon and potentially life-threatening infection of the CNS that can be caused by a range of different pathogens including bacteria, fungi, and parasites. A multidisciplinary approach is important and anti-infective treatment remains crucial. Here, we review anti-infective treatment of brain abscess. Areas covered: We used the terms '(Brain abscess[ti] AND (antibiotic* OR treatment)) NOT case report'), to conduct a search in the PubMed. Additional papers were identified by cross-reference checking and by browsing textbooks of infectious diseases and neurology.

COMMENTARY

Empiric treatment of bacterial brain abscess consists of cefotaxime and metronidazole with the addition of vancomycin if meticilline-resistant Staphylococcus aureus is suspected. For severely immuno-suppressed patients, for example transplant recipients, voriconazole and trimethoprim-sulfamethoxazole or sulfadiazine should be added. Increased knowledge of the pharmacokinetic profile of anti-infective treatments may help to improve the treatment of brain abscess. Future studies should address efficacy and safety of continuous abscess drainage, mode of anti-infective administration (continuous vs. bolus), and anti-infective treatments in immuno-suppressed patients.

Extending the Scope of 19F Hyperpolarization through Signal Amplification by Reversible Exchange in MRI and NMR Spectroscopy

Fluorinated ligands have a variety of uses in chemistry and industry, but it is their medical applications as ¹⁸F-labelled positron emission tomography (PET) tracers where they are most visible. In this work, we illustrate the potential of using ¹⁹F-containing ligands as future magnetic resonance imaging (MRI) contrast agents and as probes in magnetic resonance spectroscopy studies by significantly increasing their magnetic resonance detectability through the signal amplification by reversible exchange (SABRE) hyperpolarization method. We achieve ¹⁹F SABRE polarization in a wide range of molecules, including those essential to medication, and analyze how their steric bulk, the substrate loading, polarization transfer field, pH, and rate of ligand exchange impact the efficiency of SABRE. We conclude by presenting ¹⁹F MRI results in phantoms, which demonstrate that many of these agents show great promise as future ¹⁹F MRI contrast agents for diagnostic investigations.

Tissue Distribution and Elimination of Isavuconazole following Single and Repeat Oral-Dose Administration of Isavuconazonium Sulfate to Rats

Quantitative whole-body autoradiography was used to assess the distribution and tissue penetration of isavuconazole in rats following single and repeated oral-dose administration of radiolabeled isavuconazonium sulfate, the prodrug of isavuconazole. Following a single-dose administration of radiolabeled isavuconazonium sulfate (labeled on the active moiety), radioactivity was detectable within 1 h postdose in 56 of 65 tissue/fluid specimens. The highest maximum concentrations (C_max) were observed in bile and liver (66.6 and 24.7 μg eq/g, respectively). The lowest C_max values were in bone and eye lens (0.070 and 0.077 μg eq/g, respectively). By 144 h postdose, radioactivity was undetectable in all tissues/fluids except liver (undetectable at 336 h) and adrenal gland tissues (undetectable at 672 h). Following daily administration for up to 21 days, 1-h-postdose C_max values were the highest on or before day 14 in all except seven tissues/fluids, of which only rectum mucosa and small intestine mucosa had C_max values >25% higher than all other 1-h-postdose values. For 24-h-postdose C_max values, only large intestine, large intestine mucosa, and urine had the highest C_max values at day 21. The penetration of single oral doses of unlabeled isavuconazole (25 mg/kg of body weight isavuconazonium sulfate) and voriconazole (50 mg/kg) into rat brain (assessed using liquid chromatography-tandem mass spectrometry) was also compared. Brain concentration/plasma concentration ratios reached approximately 1.8:1 and 2:1, respectively. These data suggest that isavuconazole penetrates most tissues rapidly, reaches a steady state in most or all tissues/fluids within 14 days, does not accumulate in tissues/fluids over time, and achieves potentially efficacious concentrations in the brain.

Cerebral phaeohyphomycosis by Fonsecaea monophora: Report in a patient with AIDS and a ring enhancing lesion

Fungal infections are infrequent causes of brain abscesses. Fonsecaea monophora is a dematiaceous fungus that appears to be neurotropic. We report a case of Fonsecaea monophora infection in a patient with acquired immunodeficiency syndrome, and review previous reports of brain abscesses by this organism.

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.

Invasive mold infections in solid organ transplant recipients

Invasive mold infections represent an increasing source of morbidity and mortality in solid organ transplant recipients. Whereas there is a large literature regarding invasive molds infections in hematopoietic stem cell transplants, data in solid organ transplants are scarcer. In this comprehensive review, we focused on invasive mold infection in the specific population of solid organ transplant. We highlighted epidemiology and specific risk factors for these infections and we assessed the main clinical and imaging findings by fungi and by type of solid organ transplant. Finally, we attempted to summarize the diagnostic strategy for detection of these fungi and tried to give an overview of the current prophylaxis treatments and outcomes of these infections in solid organ transplant recipients.