Bacilos gramnegativos de crecimiento lento: grupo HACEK, Capnocytophaga y Pasteurella / Fastidious gram-negative rods: HACEK group, Capnocytophaga and Pasteurella

Las bacterias del grupo HACEK (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella), Pasteurella y Capnocytophaga son las bacterias gramnegativas de crecimiento lento que con mayor frecuencia causan infecciones en el ser humano. Forman parte de la microbiota del tracto respiratorio superior y genitourinario del ser humano y de animales, y pueden causar infecciones en cualquier localización, pero fundamentalmente de piel y tejidos blandos, así como bacteriemia y endocarditis. Su clasificación taxonó- mica es compleja y está en constante revisión. Son bacterias nutricionalmente exigentes, y para el desarrollo de colonias visibles requieren agar sangre y agar chocolate, una atmósfera aerobia, generalmente enriquecida en CO2 y una incubación de 48 h. La identificación fenotípica de especie es complicada y no siempre es posible, ya que requiere múltiples sustratos que normalmente no están disponibles en los laboratorios de rutina, ni en los sistemas automatizados. La aplicación de las técnicas moleculares y proteómicas ha permitido una mejor identificación de estas bacterias. El tratamiento de estas infecciones se encuentra con el problema de que los datos de sensibilidad a los agentes antimicrobianos son limitados; no obstante, de los datos disponibles se conoce que amoxicilina-ácido clavulánico, cefalosporinas de segunda y tercera generaciones y fluoroquinolonas son generalmente activas frente a ellas (AU)

Bacteria from the HACEK group (Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella), Pasteurella and Capnocytophaga are slow-growing gram-negative bacteria that most frequently cause infections in humans. They are part of the microbiota of the upper respiratory and genitourinary tracts of humans and animals, and can cause infections in any location, although mainly skin and soft tissue infections, as well as bacteraemia and endocarditis. Taxonomic classification is complex and under constant review. These are nutritionally demanding bacteria that require blood and chocolate agar, an aerobic atmosphere, generally CO2-enriched, and 48 h incubation for the development of visible colonies. Phenotypic identification at the species level is complicated and not always possible because it requires multiple substrates that are not normally available in routine laboratories or in automated systems. Application of molecular and proteomic techniques has enabled better identification of these bacteria. Treatment of related infections is hindered by a lack of data on susceptibility to antimicrobial agents. However, evidence suggests that amoxicillin-clavulanic acid, second- and third-generation cephalosporins and fluoroquinolones are generally active against these bacteria (AU)

Familial dementia with PrP-positive amyloid plaques: a variant of Gerstmann-Sträussler syndrome.

We present a 22-year follow-up of a large and unusual kindred previously reported as familial Alzheimer's disease (FAD). However, detailed clinical and neuropathologic evaluation of family members and brain autopsy on another affected individual now make the diagnosis of FAD unlikely. Our patient, as well as members of this family, had numerous amyloid plaques and rare neurofibrillary tangles. These plaques were quite atypical for Alzheimer's disease (AD); many were quite large (up to 500 microns in diameter) and contained several amyloid cores, some with neuritic components. The plaques were present throughout the cerebral cortex and striatum, but not in the cerebellum. By electron microscopy, they had radiating star-shaped amyloid cores containing 8- to 10-nm fibrils, and a few dystrophic neurites. They were strongly immunoreactive with antiserum to prion protein but did not react with the antiserum to the amyloid A4 protein of AD. Although the cerebellum was uninvolved, this family appears to represent another clinical and neuropathologic variant of Gerstmann-Sträussler syndrome.

[Action of O-beta-diethylaminoethylhydroxylamine on bacteriophage T2]. / Deistvie O-beta-diétilaminoétilgidroksilamina na bakteriofag T2.

A chemical modification of T2 phage DNA by O-beta-diethylaminoethylhydroxylamine was studied in situ. In the course of the reaction, cross-links between DNA and protein of the phage particle develop. The DNA-protein interaction contributes to the nucleophilic joining of hydroxylamine derivatives by C5-C6 double bond of 5-oxymethylycytosine which is a constituent of T2 phage DNA.

Slow infections of the central nervous system.

This review describes the recent advances in slow infections of the nervous system emphasizing the pathogenetic aspects of these diseases. A theoretical model for the pathogenesis of subacute sclerosing panencephalitis (SSPE) is proposed, illustrating the factors that may affect host response to the measles virus and allow it to persist and produce the panencephalitis. The isolation of an oncogenic virus from progressive multifocal leukoencephalopathy (PML) has implications in the consideration of a viral etiology for some brain tumors. The agent responsible for the transmissibility of kuru and Creutzfeldt-Jakob disease (CJD) remains uncharacterized despite recent interest in viroids and abnormalities in replication of cell membranes. The epidemiological data on multiple sclerosis suggests an exposure to an infectious agent at an early age of life modified by the host response. No specific agent has been consistently associated with multiple sclerosis. Amyotrophic lateral sclerosis (ALS), Parkinson's disease, Mollaret's meningitis and Behcet's disease are other examples where a virus is suspect but unproven. The ability of viruses to persist in the host for months to years has linked many chronic neurologic diseases to an infectious agent, enlarging the spectrum of disease caused by viruses.