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)

[Multiple sclerosis and Epstein-Barr virus : new developments and perspectives]. / Multiple Sklerose und Epstein-Barr-Virus : Neue Entwicklungen und Perspektiven.

Data from studies of twins and migrants with multiple sclerosis (MS) imply environmental factors in the development of MS. In this respect, increasing evidence indicates that Epstein-Barr virus (EBV) plays a unique role as an infectious risk factor for MS. A nearly 100% seroprevalence of antibodies to EBV in patients with MS, elevated EBV antibody titers years before clinical onset of the disease, and an increased risk for MS after symptomatic primary EBV infection (infectious mononucleosis) suggest an association of MS with a previous infection with EBV. However, the precise mechanisms through which EBV may contribute to MS are still unclear. Currently discussed potential mechanisms are outlined. The notion of a persisting (possibly immunological) change caused during the acute phase of primary EBV infection and subsequently leading to permanently elevated MS risk appears compatible with several aspects of the association found between MS and EBV.

Prognostic impact of EBV-related LMP-1, histologic type, and environmental factors in nasopharyngeal carcinoma in a German population.

INTRODUCTION: This retrospective study addressed the possible involvement of latent Epstein-Barr virus (EBV) infection, in particular LMP-1 expression, and further exogenous factors, i.e. tobacco, alcohol and occupational hazardous substances, in nasopharyngeal carcinoma (NPC) in a German population. PATIENTS AND METHODS: From 1980 to 2000, 44 patients suffering from histologically confirmed NPC were entered into the study. 33 specimens were available for immunostaining (IHC) to analyze LMP-1 expression. Information about environmental exposures were obtained employing a detailed standardized questionnaire. RESULTS: Outcome of patients with squamous cell NPC (SC-NPC) was significant worse than that of those with non-keratinizing NPC (NK-NPC). Age and tumor size correlated with response to therapy. The group with negative conventional LMP-1 staining showed better overall survival after 5 years compared to the group with positive or marginally positive LMP-1 detection (not significant). Nevertheless, after staining by tyramid-augmented IHC (TSA-IHC), nearly all specimens with negative LMP-1-staining in conventional IHC were found to be clearly positive. All patients with SC-NPC were smokers. The distribution of smokers and non-smokers in the group of NK-NPC was balanced. Comparable to the tobacco observation, there was also a correlation between high alcohol consumption and SC-NPC. CONCLUSION: Prognosis of NPC is mainly dependent on histologic type. Prognostic impact of LMP-1 is still unclear since LMP-1 was detected in all specimens using TSA-IHC. Therefore, TSA-IHC-LMP-1 detection might be interesting for diagnostic specification and development of new therapeutic strategies in NPC.

Spongiform encephalopathies in Cervidae.

The known host range of naturally-occurring transmissible spongiform encephalopathies has expanded in recent years to include wild ruminants. Chronic wasting disease (CWD) occurs in mule deer (Odocoileus hemionus hemionus) and Rocky Mountain elk (Cervus elaphus nelsoni) in Colorado and Wyoming, United States of America. These species belong to the family Cervidae. Cases have occurred primarily in captive animals but a few affected free-ranging animals have been identified. Clinical disease in both species is characterised by progressive weight loss, behavioural alterations and excessive salivation. In deer polydipsia and polyuria also commonly occur. Significant lesions are confined to the central nervous system and consist of spongiform change in grey matter, intraneuronal vacuolation, astrocytosis and amyloid plaques. Inflammatory reaction is absent. The origin of this disease is not known. In contrast to the cases of spongiform encephalopathy recognised in five species of antelope (family Bovidae) in British zoological parks, which are an extension of the current bovine spongiform encephalopathy epizootic, CWD is not the result of food-borne exposure to the infectious agent. CWD appears to be maintained within captive populations by lateral and, possibly, maternal transmission. Spongiform encephalopathies in wild ruminants are currently geographically isolated and involve relatively small numbers of animals. However, these potentially transmissible diseases could be of greater importance in the future and should be viewed with concern in the light of international movements of wild ruminants and the current expansion of the game farming and ranching industry in many parts of the world.

Sub-acute, transmissible spongiform encephalopathies: current concepts and future needs.

The first diagnosis of bovine spongiform encephalopathy (BSE) in the United Kingdom in 1986 was to stimulate the most intensive epidemiological study of any animal disease of all time in that country. It led also to the initiation of a broad-based research programme with an international flavour. This principally involved scientists and veterinarians in Europe (especially the United Kingdom) and the United States of America, especially those with experience of slow infections in general and experimental scrapie in particular. This final chapter highlights some of the significant discoveries made in the study of BSE and related diseases of this group but also emphasises the deficits in knowledge which need to be corrected before such diseases as scrapie in sheep and goats can be brought under control. The benefits resultant upon effective disease control will be manifest as improvement in animal production, welfare and, importantly, the removal of trading barriers currently in place to protect countries in which diseases such as BSE and scrapie do not exist. Of key importance is the development of a simple, cheap and effective diagnostic test for use in the live animal before the onset of clinical signs. This will be difficult since the nature of the causal agents is uncertain and none provokes either a detectable immune response or inflammatory reaction in the host. The earlier chapters, written by acknowledged specialists from around the world, deal with the specific diseases in detail and all present some of the most recent knowledge available. Here the authors emphasise the important role that major national and international agencies have in effecting the highest level of control possible in the absence of key information. International collaboration with countries in which these diseases exist, and as well as those where they are absent, is of paramount importance. It is essential that the BSE epidemic which has severely affected the cattle industry of the United Kingdom is not allowed to happen in developing countries. Whereas the former has implemented stringent control measures based on scientific knowledge and is well on the way to eradicating the disease, the latter could have much greater difficulty in establishing control. The answer is clear. BSE must be prevented from occurring elsewhere. To do that, knowledge of BSE and other members of the group should be widely dispersed and it is the purpose of this issue to do just that.

Correlation between milk and dairy product consumption and multiple sclerosis prevalence: a worldwide study.

Multiple sclerosis (MS) epidemiology suggests that different factors are involved in the clinical expression of the disease. Alimentary cofactors have already been considered, but mainly theoretically. We have studied the relationship between MS prevalence and dairy product consumption in 27 countries and 29 populations all over the world, with Spearman's correlation test. A good correlation between liquid cow milk and MS prevalence (rho = 0.836) was found; this correlation was highly significant (p < 0.001). A low but still significant correlation was obtained with cream or butter consumption (rho = 0.619 and rho = 0.504, respectively). No correlation was found for cheese. These results suggest that liquid cow milk could contain factor(s) - no longer present in the processed milk - influencing the clinical appearance of MS. The possible role of some dairy by-products is discussed in the light of a multifactorial etiology of MS.

Bovine spongiform encephalopathy: epidemiological studies on the origin.

The results of further epidemiological studies of bovine spongiform encephalopathy (BSE) support the previous findings that the onset of exposure of the cattle population to a scrapie-like agent, sufficient to result in clinical disease, occurred in 1981/82. The onset of this exposure was related to the cessation, in all but two rendering plants, of the hydrocarbon solvent extraction of fat from meat and bone meal. A further possible explanation, related to the geographical variation in the reprocessing of greaves to produce meat and bone meal, was identified for the geographical variation in the incidence of BSE.

Bovine spongiform encephalopathy.

Two years after the introduction of a slaughter policy for BSE, the author summarizes the development of the epidemic and introduction of Government controls. In conclusion, the risk to humans is discussed.

[A case of spongiform encephalopathy ("cattle madness") in a cow in Switzerland]. / Ein Fall von spongiformer Enzephalopathie ("Rinderwahnsinn") bei einer Kuh in der Schweiz.

Spongiform encephalopathies occur in humans and several domestic animal species. Among them, the bovine spongiform encephalopathy (BSE) has aroused considerable interest because of a massive outbreak of this disease in Great Britain, which is thought to result from feeding meat and bone meal contaminated with the spongiform encephalopathy agent. We observed the first case of BSE in Switzerland, which is also the first case on the European continent. A 6 year old cow suffered from progressive neurological disease. On neuropathological examination typical spongiform changes and neuronal vacuolation were found. The origin of the infection remains unknown. It cannot be excluded that the animal was exposed to cattle feed derived from Great Britain. It is possible that additional sporadic cases may occur in Switzerland, an outbreak such as in England is unlikely to happen.

Spongiform encephalopathy in an arabian oryx (Oryx leucoryx) and a greater kudu (Tragelaphus strepsiceros)

Clinical, pathological and epidemiological details of scrapie-like encephalopathies are described in an arabian oryx and a greater kudu. Clinical signs included ataxia and loss of condition with a short, progressive clinical course (22 and three days, respectively). Histopathological examination of the brains revealed spongiform encephalopathy characteristic of that observed in scrapie and bovine spongiform encephalopathy (BSE). It seems probable that these cases have a common aetiology with BSE. Scrapie-like spongiform encephalopathies have now been described in five species of exotic artiodactyls in Britain indicating a, hitherto inapparent, wider range of ruminant species as natural hosts for these diseases.