Regulation by commensal bacteria of neurogenesis in the subventricular zone of adult mouse brain.

In the mouse olfactory bulb (OB), interneurons such as granule cells and periglomerular cells are continuously replaced by adult-born neurons, which are generated in the subventricular zone (SVZ) of the brain. We have now investigated the role of commensal bacteria in regulation of such neuronal cell turnover in the adult mouse brain. Administration of mixture of antibiotics to specific pathogen-free (SPF) mice markedly attenuated the incorporation of bromodeoxyuridine (BrdU) into the SVZ cells. The treatment with antibiotics also reduced newly generated BrdU-positive neurons in the mouse OB. In addition, the incorporation of BrdU into the SVZ cells of germ-free (GF) mice was markedly reduced compared to that apparent for SPF mice. In contrast, the reduced incorporation of BrdU into the SVZ cells of GF mice was recovered by their co-housing with SPF mice, suggesting that commensal bacteria promote the incorporation of BrdU into the SVZ cells. Finally, we found that administration of ampicillin markedly attenuated the incorporation of BrdU into the SVZ cells of SPF mice. Our results thus suggest that ampicillin-sensitive commensal bacteria regulate the neurogenesis in the SVZ of adult mouse brain.

Diffusion magnetic resonance imaging diagnostic relevance in pyogenic ventriculitis with an atypical presentation: a case report.

BACKGROUND: Pyogenic ventriculitis is a rare and severe cerebral infection characterized by the presence of suppurative fluid in the cerebral ventricles. It is a life-threatening condition and may present with an aspecific neurological picture. Brain imaging techniques usually demonstrate intraventricular debris and pus, but negative imaging along with a misleading clinical picture may delay the diagnosis. CASE PRESENTATION: The described patient underwent a number of surgical procedures and eventually developed an unusual clinical picture characterized by psychomotor slowing, facial dyskinesias and myoclonic jerks without complaint of headache and in absence of meningeal irritation signs or focal neurological deficits. Cerebrospinal fluid cultural examination showed methicillin-resistant Staphylococcus aureus and vancomycin treatment lead to a complete recovery. Brain computed tomography scan was normal, while only diffusion magnetic resonance imaging sequences were able to define the presence of purulent material within the brain lateral ventriculi. CONCLUSION: The present case underlines the importance of taking into account the diagnosis of pyogenic ventriculitis even when the neurological picture does not match the suspect of a central nervous system infection. Moreover, brain computed tomography scan and standard magnetic resonance imaging sequences may be unable to confirm the diagnosis, whereas diffusion-weighted sequences prove a unique role in diagnosing cerebral pyogenic ventriculitis.

Generation of a central nervous system catheter-associated infection in mice with Staphylococcus epidermidis.

Animal models are valuable tools for investigating the in vivo pathogenesis of Staphylococcus epidermidis infections. Here, we present the procedure for generating a central nervous system catheter-associated infection in a mouse, to model the central nervous system shunt infections that frequently complicate the treatment of hydrocephalus in humans. This model uses stereotactic guidance to place silicone catheters, pre-coated with S. epidermidis, into the lateral ventricles of mice. This results in a catheter-associated infection in the brain, with concomitant illness and inflammation. This animal model is a valuable tool for evaluating the pathogenesis of bacterial infection in the central nervous system, the immune response to these infections and potential treatment options.

Multidrug-resistant Acinetobacter baumannii ventriculitis: successful treatment with intraventricular colistin.

Acinetobacter baumannii has emerged as an important nosocomial pathogen that can cause a multitude of severe infections. In neurosurgical patients the usual presentation is ventriculitis associated with external ventricular drainage. Carbapenems have been considered the gold standard for the treatment of Acinetobacter baumannii ventriculitis, but resistant isolates are increasing worldwide, reducing the therapeutic options. In many cases polymyxins are the only possible alternative, but their poor blood-brain barrier penetration could require them to be directly administered intraventricularly and clinical experience with this route is limited. We review the literature concerning intraventricular use of colistin (polymyxin E) for A. baumannii ventriculitis and add three cases successfully treated with this method. Our experience suggests that intraventricular colistin is a potentially effective and safe therapy for the treatment of multidrug-resistant A. baumannii central nervous system infections.

Risk factors for infections related to external ventricular drainage.

BACKGROUND: External ventricular drainage (EVD) is frequently used in neurosurgery for cerebrospinal fluid (CSF) drainage in patients with raised intracranial pressure. The major complication of this procedure is an EVD-related infection, i.e., meningitis or ventriculitis. The purpose of the present retrospective single centre study is to assess the possible causes of these infections. PATIENTS AND METHODS: Two hundred and twenty-eight patients were included in the period from January 1993 until April 2005. Patient and disease demographics, as well as EVD data, and the occurrence of infection were reviewed, compared, and included in a risk-analysis study. RESULTS: The population's mean age was 56 +/- 15 years and the sexes were equally distributed. Most frequently, the indication for EVD was hydrocephalus due to intraventricular haemorrhage (48.2%). An infection was documented in 23.2% of all patients. Duration of EVD drainage appeared to be a risk factor for infection (>11 days: OR 4.1; 95% CI 1.8-9.2, p = 0.001). CSF sampling frequency was also a significant risk-factor (no sampling: OR 0.2, 95% CI 0.2-0.5, p = 0.003). CONCLUSIONS: We found a relatively high percentage of EVD-related infections. After multivariate analysis there appears to be a relation with duration of drainage and frequent CSF sampling. As a result, a new EVD protocol is proposed in our institution that we believe will decrease the number of EVD-related infections to a minimum.

Solitary intraventricular tuberculoma in adults.

Intracranial tuberculoma is typically located in the parenchyma. Lesions limited to the ventricular system are uncommon. It is difficult to make a differential diagnosis from other lesions if no systemic tuberculosis is present. This study investigates a case of solitary intraventricular tuberculoma in a 19-year-old female patient with an initial clinical symptom of progressive headache. Cranial computed tomography revealed a strongly enhanced lesion in the lateral ventricle. Histopathology of the tumor demonstrated chronic inflammation, caseous necrosis, epithelioid cells and Langhans' giant cell. The culture study grew M. Tuberculosis. Solitary intraventricular tuberculoma in adults is extremely rare. Medical treatment is the preferred management method of this disease, and surgical intervention should be considered in certain situations.

Intraventricular tuberculous abscess: a case report.

Ventricles can be involved in different ways in neurotuberculosis, however, the occurrence of intraventricular abscess has been rarely reported. We report a young woman who had intraventricular tubercular abscess. Cranial computed tomographic scan showed hypodense ring enhancing lesion in the right lateral ventricle with unilateral hydrocephalus. She underwent parasagittal craniotomy with total excision of the lesion. The pus obtained from the lesion was teeming with acid fast bacilli.