Resumen La artritis séptica acromioclavicular es un cuadro sumamente infrecuente que, por lo general, se presenta en articulaciones con alta vascularización, como cadera, rodilla y hombro. El microorganismo aislado con más frecuencia es Staphylococcus aureus. Describimos a una paciente de 56 años con artritis séptica acromioclavicular, que requirió una intervención quirúrgica de urgencia. Otra particularidad del caso es el germen aislado, Staphylococcus argenteus, una bacteria muy infrecuente en este tipo de enfermedad.

Abstract Acromioclavicular septic arthritis is an extremely rare condition that usually occurs in highly vascular joints such as the hip, knee, and shoulder. The most frequently isolated pathogen is Staphylococcus aureus. In this presentation we describe a 56-year-old patient with septic arthritis at the acromioclavicular level, requiring emergency surgical intervention. As another peculiarity, the isolated germ was Staphylococcus argenteus, an extremely rare bacterium in this type of pathology.

ABSTRACT The seasonally dry subtropical forest, especially the Espinal forest in central Argentina (one of the most fragmented ecoregions), is affected by intensive agricultural activity. These activities are the main anthropogenic sources of atmospheric nitrogen compounds and their effects on lichens have been extensively studied, making them excellent ecological indicators. However, in the Espinal forest, the agricultural emissions are not monitored therefore analysis of the response of lichen diversity to these activities has a fundamental role in providing baseline data for monitoring. We analyzed changes in the frequency of families and genera of epiphytic lichen communities in 39 circular buffer areas at different scales comprising crop production, stock farming (feedlots), grazing and forest. Significant correlations at different taxonomic levels were detected in relation to land use. Frequency of Physciaceae increased with an increasing area of cropland to a distance of 600 m. Likewise a positive correlation was observed between the frequency of Collemataceae and the forest area. At genus level, Physcia presented a different response to livestock according to the intensity of production, since the frequency of these species increased in forest patches surrounded by grazing but decreased in areas with livestock farming where the stocking density is higher. This result could indicate an eutrophication process in the Espinal ecosystem, even for Physcia species. Our results can be used to start a list of indicator species to impact of agricultural in forest ecosystems.

As part of a taxonomic study which aims to revise foliose species of Physciaceae growing in central and north of Argentina, the morphology, anatomy and chemistry of Heterodermia specimens collected recently in these regions were described. Heterodermia japonica and H. fertilis are cited for the first time from Argentina. The distributional range in the country of eleven species is extended. A dichotomous key and a brief description of each species studied are provided.

Como parte de un trabajo taxonómico que tiene por objetivo revisar las especies foliosas de Physciaceae que crecen en el centro y norte de Argentina se describió la morfología, anatomía y química de especímenes de Heterodermia coleccionados recientemente en estas regiones. Se citan por primera vez para Argentina Heterodermia japonica y H. fertilis, se amplía el rango de distribución de once especies dentro del país y se presenta una clave dicotómica y una breve descripción de cada una las especies estudiadas.

Lichens are recognized bioindicators of environmental quality. Studies of lichen communities in relation to forest fires have shown the response to fire over micro-environmental variables that shape the community in the absence of this disturbance. The aim of this contribution is to recognize the effect of fire on the lichen community of Sierra Chaco in Cordoba province. Two areas were selected, one without past fire and the other with fire in 1996. Coverage and presence of lichen species on trees and shrubs were recorded in the two areas using systematic, standardized sampling. Diversity and coverage of lichens is similar between the two areas but composition varies. The lichen species in the burned area are heliophilous and adapted to stress conditions. Fire as a frequent disturbance promotes the growth of few species with high coverage that are resistant to the conditions imposed by disturbance. High intensity and high frequency fires limit development opportunities for the lichen community thus diminishing overall diversity and quality of forest systems in which they live.

Los líquenes son reconocidos bioindicadores de la calidad del ambiente. Estudios de comunidades de líquenes en relación a los incendios forestales, han demostrado como responden al fuego por encima de las variables microambientales que modelan la comunidad en ausencia de este disturbio. El objetivo de la presente contribución es reconocer el efecto del fuego en la comunidad de líquenes del Bosque Serrano en Córdoba. Se seleccionaron dos zonas, una testigo y otra sometida a fuego en 1996. A través de un muestreo sistemático y estandarizado se relevó la presencia y cobertura de especies de líquenes en árboles y arbustos en las dos áreas estudiadas. Entre el área testigo y el incendiado la diversidad y cobertura de líquenes es similar pero varia su composición. Las especies en la zona incendiadas corresponden a líquenes heliófilos y adaptados a situaciones de estrés. El fuego como disturbio frecuente favorece la presencia de pocas especies con importantes coberturas que resistan las condiciones que el disturbio impone. Los incendios de alta intensidad y frecuencia dejan a la comunidad de líquenes sin posibilidades de desarrollo, disminuyendo la diversidad general y la calidad de los sistemas forestales en los que viven.