The Prevalence of Esbl-Producing Strains of E.coli, Isolated from Calves with Colibacilosis - Preliminary Remarks

The animals producing food have become an increasing reservoir of extended spectrum beta-lactamase producing Enterobacteriaceae. The calves and cows are exposed to a greater quantity of antibiotics, but the data concerning the prevalence of ESBL-producing Enterobacteriaceae are not enough, in comparison with other species of animals used for human consumption, such as birds (Hordijk et al., 2013).The aim of this study was to determine the prevalence of ESBL-producing E. coli involved in some episodes of colibacilosis in calves. Faeces samples were collected from 33 calves with the age ranging between 1-2 weeks and that presented clinical signs of colibacilosis. The samples were collected in a sterile medium for the taxonomic isolation and identification of the etiological agent involved, the ESBL screening being conducted subsequently using the ESBL Agar Oxoid Brilliance chromogenic medium. The phenotypic confirmation of the ESBL-producing strains was conducted in accordance with the CLSI (2014) standard through the combined disc method. Following the tests conducted, out of the 33 strains of isolated E. coli, 9 (27, 27%) were phenotypically confirmed as being ESBL strains.The studies that were previously conducted on the dairy farms have pointed out that the young calves rapidly acquire bacterial strains resistant to antibiotics that are often ESBL strains (Hordijk et al., 2013). The prevalence obtained by us, as well as an insufficient quantity of information concerning the antimicrobial resistance on this segment of species of animals used for the human consumption, support conducting a more thorough study, as well as the identification of ESBL resistance genes, but also of the plasmids that encode the transmission of these genes.

The time lag between introduction and escape from cultivation of alien woody plant species decreases with polyploidization

The time between introduction of an alien species and escape from cultivation shows considerable variation among species. One hypothesis to explain this variation of the time lag invokes the evolution of genotypes adapted to the conditions of the new environment. Here, we analyse the variation in time lags among 53 alien woody plant species in Germany. Accounting for the effects of time since introduction, growth form (trees versus shrubs), biogeography and taxonomic isolation (presence or absence of a native congener in the adventive area) we found that the time lag decreases with increasing polyploidization. By contrast, the haploid chromosome number was not significantly related to the time lag. These results provide evidence for the hypothesis that recent genome duplication events are important for a fast escape from cultivation of an alien woody plant species. We suggest that a large number of duplicated chromosomes increase the partitioning of the genome and hence the average rate of recombination between loci facilitating the formation of adaptive genotypes.

Relations between body size, abundance and taxonomy of birds wintering in Britain and Ireland

We examine the relation between body size, abundance, and taxonomy in the wintering bird assemblages in Britain and Ireland. The regression slope of abundance on body size across species in both assemblages is not significantly different from that predicted by an ‘energetic equivalence rule’, but the proportion of the variance in abundance explained by body size is very low. Previous work on breeding bird assemblages has found the novel relation that the correlation between size and abundance across species within a tribe is itself positively correlated with the degree of taxonomic isolation of the tribe from other tribes in the bird fauna. We show that the same relation holds within bird tribes in the two wintering assemblages. Furthermore, evidence for this relation is found by using two different measures of bird abundance, despite these two abundance measures showing very different correlations with body size across species. Although these patterns in the data are consistent, some are not formally statistically significant ( p = 0.089 or greater). Excluding coastal, stocked, feral and recently colonizing species increased the significance of time since origin of a tribe on species abundances. We conclude that the relation between size and abundance in bird tribes is somehow related to bird taxonomy. While acknowledging the unlikely nature of such an effect, we tentatively propose hypotheses for two mechanisms that could produce the observed patterns.

Molerats (Bathyergidae, Rodentia) in South African National Parks: notes on the Taxonomic "isolation" and Hystricomorph Affinities of the family

The history of classification ofAfrotropical molerats is reviewed and an assessment is made of the supposed taxonomic "isolation" of the molerats (bathyergids) by considering morphological features in the skull, post-cranial skeleton, reproductive organs and myology which collectively point to hystricomorph affinities in contrast to a myomorph relationship which is often postulated.