Serological testing for syphilis in the differential diagnosis of cognitive decline and polyneuropathy in geriatric patients.

BACKGROUND: In the 19th century, neurosyphilis was the most frequent cause of dementia in Western Europe. Now dementia caused by syphilis has become rare in Germany. We studied whether routine testing of patients with cognitive abnormalities or neuropathy for antibodies against Treponema pallidum has therapeutic consequences in geriatric patients. METHODS: A Treponema pallidum electrochemiluminescence immunoassay (TP-ECLIA) is routinely performed in all in-patients treated at our institution with cognitve decline or neuropathy and no or insufficient previous diagnostic workup. Patients with a positive TP-ECLIA treated from October 2015 to January 2022 (76 months) were retrospectively evaluated. In cases of positive TP-ECLIA, further specific laboratory investigations were performed to assess whether antibiotic therapy was indicated. RESULTS: In 42 of 4116 patients (1.0%), TP-ECLIA detected antibodies directed against Treponema in serum. Specifity of these antibodies was ensured by immunoblot in 22 patients (11 × positiv, 11 × borderline values). Treponema-specific IgM was detectable in the serum of one patient, in 3 patients the Rapid Plasma Reagin (RPR) test, a modified Venereal Disease Research Laboratory test (VDRL), in serum was positiv. CSF analysis was performed in 10 patients. One patient had CSF pleocytosis. In 2 other patients, the Treponema-specific IgG antibody index was elevated. 5 patients received antibiotic therapy (4 × ceftriaxone 2 g/d i.v., 1 × doxycycline 300 mg/d p.o.). CONCLUSION: In approx. 1‰ of patients with previously undiagnosed or not sufficiently diagnosed cognitive decline or neuropathy, the diagnostic workup for active syphilis resulted in a course of antibiotic treatment.

[Congenital malformations of the brain misinterpreted as sequelae of poliomyelitis]. / Angeborene Fehlbildungen des Gehirns als Folgezustände der Poliomyelitis verkannt.

BACKGROUND: Poliomyelitis is an infectious disease of the peripheral motor neurons, which predominantly affects children and causes residual palsies. Because of the oral poliomyelitis vaccination started in Germany in 1960 and 1962 and the following rapid decline of the incidence of this infection, the postpolio syndrome in Germany is a disease of older people. METHODS: Since 2008, we have offered a poliomyelitis outpatient consultation at the Center of Geriatrics, Protestant Hospital Göttingen-Weende and have treated 33 patients. RESULTS: The spectrum of persistent deficits after poliomyelitis ranges from palsy of single extremities to severe disability with (temporary) ventilator dependence. Many patients suffer from scoliosis or shortening of limbs of different degrees, which promotes degenerative diseases of the spinal cord and joints with secondary myelopathy, injury of spinal nerve roots or peripheral nerves or respiratory failure. The postpolio syndrome is characterized by an increase of the functional deficits after decades of compensation. The palsies of 2 of the 33 patients were not caused by poliomyelitis but by myelomeningocele and schizencephaly, respectively. CONCLUSION: The motor deficits acquired in childhood enable the majority of the patients to successfully master their lives. Because of the limited compensatory capacities of postpolio patients, even small increases in the severity of the palsy can cause a severe decline of the functional status and an impairment of the ability to live an independent life. In a substantial proportion of patients with the diagnosis poliomyelitis the symptoms are caused by other diseases.

Multiple Triplet Metal-Centered Jahn-Teller Isomers Determine Temperature-Dependent Luminescence Lifetimes in [Ru(bpy)3 ]2.

Understanding the factors that determine the luminescence lifetime of transition metal compounds is key for applications in photocatalysis and photodynamic therapy. Here we show that for [ Ru ( bpy ) 3 ] 2 + ${[{\rm{Ru}}({\rm{bpy}})_{\rm{3}} ]^{{\rm{2 + }}} }$ (bpy = 2,2'-bipyridine), the generally accepted idea that emission lifetimes can be controlled optimizing the energy barrier from the emissive triplet metal-to-ligand charge-transfer (3 MLCT) state to the thermally-activated triplet metal-centered (3 MC) state or the energy gap between both states is a misconception. Further, we demonstrate that considering a single relaxation pathway determined from the minimum that is lowest in energy leads to wrong temperature-dependent emission lifetimes predictions. Instead, we obtain excellent agreement with experimental temperature-dependent lifetimes when an extended kinetic model that includes all the pathways related to multiple Jahn-Teller isomers and their effective reaction barriers is employed. These concepts are essential to correctly design other luminescent transition metal complexes with tailored emission lifetimes based on theoretical predictions.

Spatial and temporal variation of routine parameters: pitfalls in the cerebrospinal fluid analysis in central nervous system infections.

The cerebrospinal fluid (CSF) space is convoluted. CSF flow oscillates with a net flow from the ventricles towards the cerebral and spinal subarachnoid space. This flow is influenced by heartbeats, breath, head or body movements as well as the activity of the ciliated epithelium of the plexus and ventricular ependyma. The shape of the CSF space and the CSF flow preclude rapid equilibration of cells, proteins and smaller compounds between the different parts of the compartment. In this review including reinterpretation of previously published data we illustrate, how anatomical and (patho)physiological conditions can influence routine CSF analysis. Equilibration of the components of the CSF depends on the size of the molecule or particle, e.g., lactate is distributed in the CSF more homogeneously than proteins or cells. The concentrations of blood-derived compounds usually increase from the ventricles to the lumbar CSF space, whereas the concentrations of brain-derived compounds usually decrease. Under special conditions, in particular when distribution is impaired, the rostro-caudal gradient of blood-derived compounds can be reversed. In the last century, several researchers attempted to define typical CSF findings for the diagnosis of several inflammatory diseases based on routine parameters. Because of the high spatial and temporal variations, findings considered typical of certain CNS diseases often are absent in parts of or even in the entire CSF compartment. In CNS infections, identification of the pathogen by culture, antigen detection or molecular methods is essential for diagnosis.

Intrathecal Antibacterial and Antifungal Therapies.

Intrathecal administration of anti-infectives is indicated in central nervous system infections by multiresistant pathogens when drugs that can reach adequate cerebrospinal fluid (CSF) concentrations by systemic therapy are not available. Antibiotics that readily pass the blood-brain and blood-CSF barriers and/or that have low toxicity allowing an increase in the daily dosage should not be used for intrathecal therapy. Intrathecal therapy is accompanied by systemic treatment. Antibacterials indispensable for intrathecal therapy include aminoglycosides, colistin, daptomycin, tigecycline, and vancomycin. Limited experience suggests the utility of the antifungals amphotericin B and caspofungin. Intraventricular administration ensures distribution throughout the CSF compartment, whereas intralumbar dosing often fails to attain adequate antibiotic concentrations in the ventricles. The individual dose is determined by the estimated size of the CSF space and by the estimated clearance from CSF. For moderately lipophilic anti-infectives with a molecular weight above approximately 1,000 g/mol, as well as for hydrophilic drugs with a molecular weight above approximately 400 g/mol, one daily dose is normally adequate. The ventricular drain should be clamped for 15 to 120 min to facilitate the distribution of the anti-infective in the CSF space. Therapeutic drug monitoring of the trough levels is necessary only in cases of therapeutic failure.

Central nervous system infections and antimicrobial resistance: an evolving challenge.

PURPOSE OF REVIEW: Antimicrobial resistance is an increasing threat to patients also in nosocomial central nervous system (CNS) infections. The present review focusses on optimizing intravenous treatment in order to achieve sufficient concentrations of antibiotics in the different compartments of the CNS when the causative pathogens have reduced sensitivity to antibiotics or/and the impairment of the blood-cerebrospinal fluid (CSF) and blood-brain barrier is mild. RECENT FINDINGS: Experience has been gathered with treatment protocols for several established antibiotics using increased doses or continuous instead of intermittent intravenous therapy. Continuous infusion in general does not increase the average CSF concentrations (or the area under the concentration-time curve in CSF) compared to equal daily doses administered by short-term infusion. In some cases, it is postulated that it can reduce toxicity caused by high peak plasma concentrations. In case reports, new ß-lactam/ß-lactamase inhibitor combinations were shown to be effective treatments of CNS infections. SUMMARY: Several antibiotics with a low to moderate toxicity (in particular, ß-lactam antibiotics, fosfomycin, trimethoprim-sulfamethoxazole, rifampicin, vancomycin) can be administered at increased doses compared to traditional dosing with low or tolerable adverse effects. Intrathecal administration of antibiotics is only indicated, when multiresistant pathogens cannot be eliminated by systemic therapy. Intravenous should always accompany intrathecal treatment.

Reduced Clostridioides difficile infections in hospitalised older people through multiple quality improvement strategies.

OBJECTIVES: To reduce infections with Clostridioides difficile (CDI) in geriatric patients by interventions easily implementable in standard clinical care. METHODS: Prevalence and incidence of CDI between January 2015 and February 2020 were analysed (n = 25,311 patients). Pre-intervention status was assessed from April 2016 to March 2017 (n = 4,922). Between May 2017 and August 2019, a monocentric interventional crossover study (n = 4,655) was conducted including standard care and three interventions: (A) sporicidal cleaning of hospital wards, (B) probiotics and (C) improvement in personal hygiene for CDI patients. This was followed by a multicentric comparison of the interventional bundle (A + B + C) between September 2019 and February 2020 (n = 2,593) with the pre-intervention phase. In 98 CDI cases and matched controls individual risk factors for the development of CDI were compared. RESULTS: Time series analyses of CDI cases revealed a reduction in the prevalence of CDI in all three participating centres prior to the multicentric intervention phase. In the monocentric phase, no effect of individual interventions on CDI prevalence was identified. However, an aggregated analysis of CDI cases comparing the pre-intervention and the multicentric phase revealed a significant reduction in CDI prevalence. Risk factors for the development of CDI included use of antibiotics, anticoagulants, previous stay in long-term care facilities, prior hospital admissions, cardiac and renal failure, malnutrition and anaemia. CONCLUSIONS: The observed reduction in CDI may be attributed to heightened awareness of the study objectives and specific staff training. Individual interventions did not appear to reduce CDI prevalence. A further randomised trial would be necessary to confirm whether the bundle of interventions is truly effective.

Pre-treatment with the viral Toll-like receptor 3 agonist poly(I:C) modulates innate immunity and protects neutropenic mice infected intracerebrally with Escherichia coli.

BACKGROUND: Individuals with impaired immunity are more susceptible to infections than immunocompetent subjects. No vaccines are currently available to induce protection against E. coli meningoencephalitis. This study evaluated the potential of poly(I:C) pre-treatment to induce trained immunity. Poly(I:C) was administered as a non-specific stimulus of innate immune responses to protect immunocompetent and neutropenic wild-type mice from a subsequent challenge by the intracranial injection of E. coli K1. METHODS: Three days prior to infection, mice received an intraperitoneal injection of poly(I:C) or vehicle. Kaplan-Meier survival curves were analyzed. In short-term experiments, bacterial titers and the inflammatory response were characterized in the blood, cerebellum, and spleen homogenates. NK cell subpopulations in the brain and spleen were analyzed by flow cytometry. Numbers of microglia and activation scores were evaluated by histopathology. RESULTS: Pre-treatment with 200 µg poly(I:C) increased survival time, reduced mortality, and enhanced bacterial clearance in the blood, cerebellum, and spleen at early infection in neutropenic mice. Poly(I:C)-mediated protection correlated with an augmented number of NK cells (CD45+NK1.1+CD3-) and Iba-1+ microglial cells and a higher production of IFN-γ in the brain. In the spleen, levels of CCL5/RANTES and IFN-γ were increased and sustained in surviving poly(I:C)-treated animals for 14 days after infection. In immunocompetent animals, survival time was not significantly prolonged in poly(I:C)-treated animals although poly(I:C) priming reduced brain bacterial concentrations compared with vehicle-injected animals at early infection. CONCLUSIONS: Pre-treatment with the viral TLR3 agonist poly(I:C) modulated innate immune responses and strengthened the resistance of neutropenic mice against E. coli K1 meningoencephalitis.

HIF-1α is involved in blood-brain barrier dysfunction and paracellular migration of bacteria in pneumococcal meningitis.

Bacterial meningitis is a deadly disease most commonly caused by Streptococcus pneumoniae, leading to severe neurological sequelae including cerebral edema, seizures, stroke, and mortality when untreated. Meningitis is initiated by the transfer of S. pneumoniae from blood to the brain across the blood-cerebrospinal fluid barrier or the blood-brain barrier (BBB). The underlying mechanisms are still poorly understood. Current treatment strategies include adjuvant dexamethasone for inflammation and cerebral edema, followed by antibiotics. The success of dexamethasone is however inconclusive, necessitating new therapies for controlling edema, the primary reason for neurological complications. Since we have previously shown a general activation of hypoxia inducible factor (HIF-1α) in bacterial infections, we hypothesized that HIF-1α, via induction of vascular endothelial growth factor (VEGF) is involved in transmigration of pathogens across the BBB. In human, murine meningitis brain samples, HIF-1α activation was observed by immunohistochemistry. S. pneumoniae infection in brain endothelial cells (EC) resulted in in vitro upregulation of HIF-1α/VEGF (Western blotting/qRT-PCR) associated with increased paracellular permeability (fluorometry, impedance measurements). This was supported by bacterial localization at cell-cell junctions in vitro and in vivo in brain ECs from mouse and humans (confocal, super-resolution, electron microscopy, live-cell imaging). Hematogenously infected mice showed increased permeability, S. pneumoniae deposition in the brain, along with upregulation of genes in the HIF-1α/VEGF pathway (RNA sequencing of brain microvessels). Inhibition of HIF-1α with echinomycin, siRNA in bEnd5 cells or using primary brain ECs from HIF-1α knock-out mice revealed reduced endothelial permeability and transmigration of S. pneumoniae. Therapeutic rescue using the HIF-1α inhibitor echinomycin resulted in increased survival and improvement of BBB function in S. pneumoniae-infected mice. We thus demonstrate paracellular migration of bacteria across BBB and a critical role for HIF-1α/VEGF therein and hence propose targeting this pathway to prevent BBB dysfunction and ensuing brain damage in infections.

High dose vitamin D exacerbates central nervous system autoimmunity by raising T-cell excitatory calcium.

Poor vitamin D status is associated with a higher relapse rate and earlier disability in multiple sclerosis. Based on these associations, patients with multiple sclerosis are frequently supplemented with the vitamin D precursor cholecalciferol, although it is unclear whether this regimen is of therapeutic benefit. To model consequences of this common practice, mice were fed for more than 3 months with a low, medium or high dose of cholecalciferol, representative of vitamin D deficiency, modest and disproportionally high supplementation, respectively, in patients with multiple sclerosis. Compared to vitamin D-deprived mice, its moderate supplementation reduced the severity of subsequent experimental autoimmune encephalomyelitis, which was associated with an expansion of regulatory T cells. Direct exposure of murine or human T cells to vitamin D metabolites inhibited their activation. In contrast, mice with 25-(OH) vitamin D levels above 200 nmol/l developed fulminant experimental autoimmune encephalomyelitis with massive CNS infiltration of activated myeloid cells, Th1 and Th17 cells. When dissecting this unexpected outcome, we observed that high, but not medium dose vitamin D had caused mild hypercalcaemia, which rendered T cells more prone to pro-inflammatory activation. Exposing murine or human T cells to equivalent calcium concentrations in vitro enhanced its influx, triggering activation, upregulation of pro-inflammatory gene products and enhanced transmigration across a blood-brain barrier model. These findings suggest that vitamin D at moderate levels may exert a direct regulatory effect, while continuous high dose vitamin D treatment could trigger multiple sclerosis disease activity by raising mean levels of T-cell excitatory calcium.

Training improves the handling of inhaler devices and reduces the severity of symptoms in geriatric patients suffering from chronic-obstructive pulmonary disease.

PURPOSE: Elderly patients with impaired vision, cognitive decline or motor/sensory disturbances of their fingers suffering from chronic-obstructive pulmonary disease (COPD) encounter difficulties in handling inhaler devices used as the cornerstones of treatment of pulmonary obstruction. Many elderly patients make severe mistakes which impede adequate drug delivery to the bronchioles. This multimodal training program was designed to reduce the number of handling mistakes of inhaler devices. METHODS: From October 1, 2016 to September 30, 2017, a prospective intervention study was conducted in 38 in-patients > 65 years (median age 79 years) with previously diagnosed COPD. The effect of an 8-day intervention comprising daily counselling and video demonstration according to the recommendations of the German Airway League on the frequency of mistakes during handling of inhaler devices, the forced expiratory volume in 1 s (FEV1), the forced vital capacity (FVC) and the perception of symptoms (COPD Assessment Test, CAT) were studied. Measurements on days 1 and 8 were compared by Wilcoxon signed rank test. RESULTS: The number of handling mistakes per patient decreased as a consequence of the intervention from 3.0 (0-7) to 0.5 (0-6) [median (minimum-maximum; p < 0.0001)]. The CAT Score decreased from 19.5 (14/24) to 14.5 (10.75/21) [median (25./75. percentile; p < 0.0001) indicating a substantial reduction of clinical symptoms. Conversely, FEV1 and FVC only slightly increased (difference statistically not significant). At study entry, the number of handling mistakes was inversely correlated with the Mini Mental Status Test (MMST) score (p = 0.01). The reduction of the number of handling mistakes during the intervention was not correlated with the MMST. CONCLUSION: In COPD, intensive training for 8 days improved the handling of inhalers and reduced clinical symptoms in geriatric patients. Patients with cognitive abnormalities also benefitted from this intervention. TRIAL REGISTRATION: German Clinical Trials Registry DRKS00023196 , date of registration September 29, 2020 (retrospectively registered).

Neurogeriatrics-a vision for improved care and research for geriatric patients with predominating neurological disabilities.

Geriatric medicine is a rapidly evolving field that addresses diagnostic, therapeutic and care aspects of older adults. Some disabilities and disorders affecting cognition (e.g. dementia), motor function (e.g. stroke, Parkinson's disease, neuropathies), mood (e.g. depression), behavior (e.g. delirium) and chronic pain disorders are particularly frequent in old subjects. As knowledge about these age-associated conditions and disabilities is steadily increasing, the integral implementation of neurogeriatric knowledge in geriatric medicine and specific neurogeriatric research is essential to develop the field. This article discusses how neurological know-how could be integrated in academic geriatric medicine to improve care of neurogeriatric patients, to foster neurogeriatric research and training concepts and to provide innovative care concepts for geriatric patients with predominant neurological conditions and disabilities.

Medication and medical diagnosis as risk factors for falls in older hospitalized patients.

OBJECTIVE: To examine the impact of medication and medical conditions on the fall risk in older hospitalized patients. DESIGN: Matched case-control study. SETTING: Large regional hospital in a mid-sized German city. SUBJECTS: Four hundred eighty-one inpatients aged ≥ 65 years who fell during hospitalization ("cases") and a control group of 481 controls, matched for age, gender, and hospital department. METHODS: Diagnosis, medication, vital parameters, and injuries were compared between cases and controls. Univariate and multivariable odds ratios (ORs) and their corresponding 95% confidence intervals (CIs) were calculated. MAIN RESULTS: Several drugs were significantly associated with falls in multivariate analyses: long-acting benzodiazepines (adjusted OR = 3.49; 95%-CI = 1.16-10.52), serotonin-noradrenalin reuptake inhibitors (SNRI) (2.57; 1.23-5.12), Z-drugs (2.29; 1.38-3.59), low-potency neuroleptics (1.87; 1.08-3.23), ACE inhibitors/sartans (1.42; 1.07-1.89). Digoxin (0.32; 0.11-0.99) and aldosterone receptor antagonists (0.54; 0.33-0.88) were negatively associated with falls. No significant association in multivariate analyses was found for short- and intermediate-acting benzodiazepines, mirtazapine, and opioids. Hyponatremia (1.52; 1.15-2.03) and leukocytosis (1.39; 1.05-1.87) in blood examination on admission showed significant association with falls. As secondary diagnoses, Parkinson syndrome (2.38; 1.27-4.46) and delirium (3.74; 2.26-6.21) were strongly associated with falls. The use of more than one psychoactive drug was a separate risk factor for falls (p < 0.0001). CONCLUSION: Several drugs including SNRI, neuroleptics, and Z-drugs showed a significant association with inpatient falls. The frequently prescribed tetracyclic antidepressant mirtazapine did not appear to increase the risk of falls. Psychoactive polypharmacy should be avoided.

The interplay of context factors in hypnotic and sedative prescription in primary and secondary care-a qualitative study.

PURPOSE: Non-medical or contextual factors strongly influence physicians' prescribing behavior and may explain why drugs, such as benzodiazepines and Z-drugs, are still frequently prescribed in spite of well-known adverse effects. This study aimed to explore which contextual factors influence the prescription of hypnotics and sedatives and to compare their role in primary and secondary care. METHODS: Understanding medical practices as games with specific rules and strategies and performed in a largely habitual, not fully conscious manner, we asked a maximum variation sample of 12 hospital doctors and 12 general practitioners (GPs) about their use of hypnotics and sedatives. The interviews were analyzed by qualitative content analysis. RESULTS: Hospital doctors' and GPs' use of hypnotics and sedatives was influenced by a variety of contextual factors, such as the demand of different patient groups, aims of management, time resources, or the role of nurses and peers. Negotiating patient demands, complying with administrative regulations, and finding acceptable solutions for patients were the main challenges, which characterized the game of drug use in primary care. Maintaining the workflow in the hospital and finding a way to satisfy both nurses and patients were the main challenges in secondary care. CONCLUSIONS: Even if doctors try to act rationally, they cannot escape the interplay of contextual factors such as handling patient needs, complying with administrative regulations, and managing time resources. Doctors should balance these factors as if they were challenges in a complex game and reflect upon their own practices.

Patient-reported factors associated with the desire to continue taking sleep-inducing drugs after hospital discharge: A survey of older adults.

PURPOSE: To find out whether any prior experiences with sleep-inducing drugs before hospitalization and positive experiences with these drugs during hospitalization influence a patient's wish to continue taking sleep-inducing drugs after hospitalization. METHODS: We surveyed older hospital patients about use of sleep-inducing drugs before, during, and after hospitalization and compared these answers with their hospital chart using the kappa statistic. The association between the wish to continue these drugs after discharge and the perceived benefits, experience of side effects, and prior experience with sleep-inducing drugs was determined by multivariable logistic regression. RESULTS: Agreement between patient responses and the hospital file was high (κ = 0.7). Seventeen percent (83/483) of the participants reported prior experience before their hospital stay; 45% received a sleep-inducing drug during hospitalization; 17% wished to continue taking them after discharge. Of the 400 patients who had no prior experience with sleep-inducing drugs, 147 (37%) became first-time users in the hospital, and 27% (40/147) of these wished to continue this medication after discharged. Strong predictors for this wish were the reduction of sleep onset problems (adjusted odds ratio, 6.26; 95% confidence interval, 2.38-16.44) and any prior experience with sleep-inducing drugs (4.08; 1.97-8.48). CONCLUSIONS: Many older patients become first-time users of sleep-inducing drugs in the hospital. Especially the experience of sleep onset improvements influences the wish to continue sleep-inducing drug use after discharge. Avoiding first-time use should become a goal of hospital policy and be taken into account when weighing the benefits and risks of sleep-inducing drugs.

Activin A increases phagocytosis of Escherichia coli K1 by primary murine microglial cells activated by toll-like receptor agonists.

BACKGROUND: Bacterial meningitis is associated with high mortality and long-term neurological sequelae. Increasing the phagocytic activity of microglia could improve the resistance of the CNS against infections. We studied the influence of activin A, a member of the TGF-ß family with known immunoregulatory and neuroprotective effects, on the functions of microglial cells in vitro. METHODS: Primary murine microglial cells were treated with activin A (0.13 ng/ml-13 µg/ml) alone or in combination with agonists of TLR2, 4, and 9. Phagocytosis of Escherichia coli K1 as well as release of TNF-α, IL-6, CXCL1, and NO was assessed. RESULTS: Activin A dose-dependently enhanced the phagocytosis of Escherichia coli K1 by microglial cells activated by agonists of TLR2, 4, and 9 without further increasing NO and proinflammatory cytokine release. Cell viability of microglial cells was not affected by activin A. CONCLUSIONS: Priming of microglial cells with activin A could increase the elimination of bacteria in bacterial CNS infections. This preventive strategy could improve the resistance of the brain to infections, particularly in elderly and immunocompromised patients.

Pharmacokinetics and pharmacodynamics of antibiotics in central nervous system infections.

PURPOSE OF REVIEW: The barriers surrounding the central nervous system (CNS) together with the emergence of multiresistant pathogens pose a therapeutic challenge for the effective treatment of CNS infections. RECENT FINDINGS: In addition to vancomycin, colistin and aminoglycosides, classically used for intrathecal injection, drug concentrations in cerebrospinal fluid after intrathecal injection of daptomycin and tigecyclin were recently studied. SUMMARY: The entry of antiinfectives into the CNS compartments is determined by the physicochemical properties of the drug and by conditions in the host. The most important drug properties are lipophilicity at a neutral pH, molecular mass and drug binding to serum proteins. In clinical practice, active transport is of importance only for some drugs. In recent years, intrathecal injection of antiinfectives in addition to systemic therapy has regained attention as a means to achieve high cerebrospinal fluid concentrations. The classification of antibacterials and antifungals into time-dependent and concentration-dependent compounds is also valid for the CNS compartments.

The inflammatory response and neuronal injury in Streptococcus suis meningitis.

BACKGROUND: Many of the currently used models of bacterial meningitis have limitations due to direct inoculation of pathogens into the cerebrospinal fluid or brain and a relatively insensitive assessment of long-term sequelae. The present study evaluates the utility of a Streptococcus (S.) suis intranasal infection model for the investigation of experimental therapies in meningitis. METHODS: We examined the brains of 10 piglets with S. suis meningitis as well as 14 control piglets by histology, immunohistochemistry and in-situ tailing for morphological alterations in the hippocampal dentate gyrus and microglial activation in the neocortex. RESULTS: In piglets with meningitis, the density of apoptotic neurons was significantly higher than in control piglets. Moreover, scoring of microglial morphology revealed a significant activation of these cells during meningitis. The slight increase in the density of dividing cells, young neurons and microglia observed in piglets suffering from meningitis was not statistically significant, probably because of the short time frame between onset of clinical signs and organ sampling. CONCLUSIONS: The morphological changes found during S. suis meningitis are in accordance with abnormalities in other animal models and human autopsy cases. Therefore, the pig should be considered as a model for evaluating effects of experimental therapeutic approaches on neurological function in bacterial meningitis.

Age does not influence the disease course in a mouse model of Streptococcus pneumoniae serotype 3 meningitis.

In order to elucidate the causes for the increased mortality of aged patients with bacterial central nervous system (CNS) infections, we compared the course of Streptococcus pneumoniae (S. pneumoniae) meningitis in aged and young mice. Aged (21.2 ± 3.1 months, n = 40) and young (3.2 ± 0.9 months, n = 42) C57BL/6N and B6/SJL mice were infected by intracerebral injection of 50-70 CFU S. pneumoniae serotype 3 and monitored for 15 days. Aged and young mice did not differ concerning mortality (35% versus 38%), weight loss, development of clinical symptoms, bacterial concentrations in cerebellum and spleen as well as the number of leukocytes infiltrating the CNS. In contrast to results from our geriatric mouse model of Escherichia coli (E. coli) meningitis, where aged mice showed a higher mortality and an impaired elimination of bacteria, we did not find any differences between aged and young mice after intracerebral infection with S. pneumoniae serotype 3. This indicates that the increased susceptibility of aged mice to bacterial CNS infections is pathogen-specific: It appears less prominent in infections caused by hardly phagocytable pathogens with thick capsules like S. pneumoniae serotype 3, where the age-related decline of the phagocytic capacity of microglia and macrophages has a minor influence on the disease course.

The Early Adaptive Immune Response in the Pathophysiological Process of Pneumococcal Meningitis.

BACKGROUND: The adaptive immune system has been considered to play a minimal role in the early host response during bacterial meningitis. METHODS: We investigated the progression and outcome of pneumococcal meningitis in Rag1-/- mice lacking functional B and T cells by assessing overall and symptom-free survival, bacteriological and histological studies, as well as flow cytometry and measurements of proinflammatory mediators. RESULTS: The intracerebral injection of S. pneumoniae D39 induced the recruitment of B and T cells (CD4+, γδ and natural killer) into the brain of wild-type mice. Mice with no functional B and T cells developed clinical symptoms and succumbed to the infection earlier than the wild-type group. In the CNS, Rag1-/- mice showed lower levels of interleukin 1ß, reduced microglial proliferation, and impaired granulocyte recruitment with an earlier spread of pneumococci into the bloodstream, compared with wild-type mice. Lack of B and T cells resulted in a severe impairment of bacterial clearance in blood, spleen, and liver and an exaggerated systemic inflammatory response. CONCLUSIONS: B and T cells are important effector cells delaying the spread of pneumococci from the brain to the systemic circulation and shaping the immune response, thereby prolonging the survival of the host in the absence of antibiotic treatment.