AFLP-PCR and RAPD-PCR evidences of the transmission of the pathogen Aphanomyces astaci (Oomycetes) to wild populations of European crayfish from the invasive crayfish species, Procambarus clarkii.

Aphanomyces astaci (Oomycetes) is responsible for the crayfish plague disease. This species is endemic of North America and five genotypes have been described using RAPD-PCR. The red swamp crayfish, Procambarus clarkii, is one of the most widely spread North American species and invasive in the world. However, no outbreaks on its specific genotype, i.e., genotype D, have ever been described in nature. We investigated three major series of crayfish plague outbreaks in indigenous crayfish populations of Austropotamobius pallipes, located in the areas of influence of P. clarkii. All samples collected tested positive for A. astaci using a rnDNA ITS-PCR test. We also performed an AFLP-PCR analysis on 19 isolates, and found that all isolates belong to genotype D. These isolates exhibited similar properties, i.e., adaptation to warm temperatures. We demonstrate, for the first time, the transmission of A. astaci genotype D to indigenous European populations of crayfish, and confirm that the properties of adaptation to warm water temperatures seem to be a specific character of genotype D. The results of this work emphasize once more the need of controlling invasive species and its trade, since they can carry harmful pathogens with specific adaptations or increased virulence in new environments.

[Mortality risk factors in descending necrotizing mediastinitis]. / Factores de riesgo de mortalidad en la mediastinitis necrosante descendente.

INTRODUCTION: The term descending necrotizing mediastinitis (MND) refers to an infection that begins in the oropharyngeal region and spreads through the fascial planes into the mediastinum. This study aims to estimate the incidence of MND in our centre, the epidemiology and clinical features of the disease and to evaluate prognostic factors influencing mortality. PATIENTS AND METHODS: We performed a retrospective study on 43 consecutive patients diagnosed at the Hospital Universitari Vall d'Hebron in Barcelona from January 1996 to December 2006. We performed a descriptive study and a bivariate and a multivariate analysis of variables collected. RESULTS: Overall mortality was 21%, but when we subdivided the study into two periods (1996-2000 and 2001-2006) it shows a significant decrease (40% versus 4.3%). Risk factors identified in the bivariate analysis were: diagnosis period 1996-2000, diabetes mellitus, comorbidity, number of surgeries, left lateral surgery, postoperative morbidity and septic shock. In multivariate analysis, only the presence of septic shock proved to be an independent predictor of mortality. CONCLUSIONS: MND is a disease of low incidence and should be suspected clinically and confirmed immediately with a computed tomography (CT). Multidisciplinary and early treatment has allowed us to reduce mortality by 40% in the first initial period to 4.3% today.