RESUMEN
A highly conserved fragment adjacent to the cfb gene encoding the CAMP factor is the target of PCR-based molecular diagnostic systems for the identification of S. agalactiae (group B streptococci (GBS)). Six PCR-negative, culture-positive GBS strains were whole genome sequenced to assess why they escaped molecular diagnostics. GBS strains did not constitute a clonal cluster and presented variably sized chromosomal deletions (from 7 to 33 kb) which always included the cfb gene, a finding never described before. GBS strains that escape molecular diagnostics are considered rare; however, they can cause false-negative results using molecular diagnostics alone, affecting medical decisions.
Asunto(s)
Proteínas Bacterianas , Proteínas Hemolisinas , Infecciones Estreptocócicas , Streptococcus agalactiae , Streptococcus agalactiae/genética , Proteínas Bacterianas/genética , Secuenciación Completa del Genoma , Genoma Bacteriano , Infecciones Estreptocócicas/diagnóstico , Humanos , Proteínas Hemolisinas/genética , Femenino , Técnicas de Diagnóstico Molecular , Técnicas de Tipificación BacterianaRESUMEN
PURPOSE: The aim of this study was to verify the sensitivity and specificity of the hyperdense middle cerebral artery sign (HMCAS) obtained by multidetector computed tomography (CT) in predicting acute stroke, using diffusion-weighted (DW) magnetic resonance imaging (MRI) as a reference. The location of the HMCAS, the extension of the ischaemic lesion and its prognostic value were also assessed. MATERIALS AND METHODS: The CT examinations of 654 patients with symptoms related to acute cerebral stroke were retrospectively reviewed. DW-MRI confirmed recent stroke in 175 patients. Two expert neuroradiologists analysed the CT examinations of these patients in four phases. Sensitivity, specificity and interobserver reliability was evaluated. Patients were divided into three groups according to the HMCAS site (M1-M2-M3) and the Alberta Stroke Program Early CT Score (ASPECTS) on DW-MRI was calculated. The ASPECTS average score was correlated with the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin scale (mRS) at 3 months. RESULTS: In 41 patients, the presence of HMCAS was confirmed (71 % sensitivity; 100 % specificity; Interobserver reliability k, 84 %). An inverse correlation was found by comparing the ASPECTS and NIHSS scores (Rsq = -0.206). After logistic regression analysis, HMCAS was found to be independently associated with a poor outcome (mRS >2) at 3 months after adjusting for age, NIHSS on admission, risk factors and aetiology of stroke. CONCLUSIONS: Our study demonstrated that HMCAS obtained with multidetector CT can be detected in more than 70 % of patients with large acute ischaemic lesion and it is an unfavourable prognostic sign.
Asunto(s)
Isquemia Encefálica/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética , Arteria Cerebral Media/diagnóstico por imagen , Tomografía Computarizada Multidetector , Accidente Cerebrovascular/diagnóstico por imagen , Enfermedad Aguda , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Pronóstico , Reproducibilidad de los Resultados , Estudios Retrospectivos , Sensibilidad y EspecificidadRESUMEN
The identification of diffuse axonal injury (DAI) can be difficult, especially using conventional imaging (CT or MRI), which usually appears normal. Diffusion tensor imaging (DTI) is useful in identifying white matter abnormalities in patients with DAI. We describe the case of a 17-year-old female with severe closed head injury and right-side hemiparesis, studied with DTI and MR-tractography. In this case, DTI was useful to detect focal and diffuse signs of DAI.