All Posts Tagged With: "Escherichia coli"

Link: http://www.cdc.gov/ncidod/eid

Excerpt:

Bacterial Population Genetics in Infectious Disease addresses a set of issues that are extremely provocative in the current climate in which progress is rapidly changing the microbiological landscape. From this perspective, the volume appears at a key moment because of 2 major challenges that have arisen since the beginning of the genomic era: 1) defining what constitutes a species and how to determine this, and 2) determining the structure of the population of the most common bacterial pathogens.

The book opens with a review of the concepts and methods that make it possible to analyze bacterial populations genetically. This presentation immediately brings to the forefront the question of how to define what constitutes a bacterial species (if there is conceptually even such a thing) and the variable evolutionary nature of bacteria. The differences among complexes within species, species, and clones are shown with clear diagrams useful for teaching. In addition, the text also evaluates the lateral transfer of genes, one of the elements that constitute the bacterial genome repertoire, including its effects on the attempts at classification of bacteria. The evolutionary demography of bacterial populations is then examined. These concepts are essential for comprehending and teaching modern microbiology.

In addition, the text describes techniques for evaluating bacterial diversity, such as the search for single-nucleotide polymorphisms or repeats by using sequences encoding proteins or not. These techniques can play a key part in the identification of the clones.

The second part of the book is specifically relevant to clinical microbiology, particularly to emerging bacterial pathogens. The genetic populations of Bacillus anthracis,Campylobacter spp., Enterococcus spp., Borrelia burdorferi, Neisseria meningitidis,Escherichia coli, Salmonella spp., Staphylococcus spp., and Streptococcus spp. are analyzed. The importance of genomic recombinations in microbial evolution is particularly stressed for Streptococcus spp., Neisseria spp., and E. coli, for which the number of recombinations is considered to be higher than that of the number of changes; this conclusion likely alters our perception of the evolution of bacteria. Lastly, a general hypothesis is proposed for Salmonella spp.: that their antigens are selected by passage through specific phagocytic protists from their animal hosts with which they have cospeciation. This assumption is bold and intriguing.

Full article: http://eutils.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&id=20699042&retmode=ref&cmd=prlinks

Excerpt:

A 71-year-old man was referred to our outpatient clinic because
of arthralgia and swelling of his right hand. He also showed a
subcutaneous nodule on his left knee. A second patient, a
57-year-old woman, was referred because of painful skin of her
legs. Dermatologic examination revealed erythemateous livid
discoloration on both feet and legs. There were reticular
varices, corona flebectatia paraplantaris medialis and minimal
pitting oedema. Serology tested positive in both patients for
Borrelia and they both recalled tick bites. A third patient, a
73-year-old woman, was referred because of erythema and maculae
located at her lower legs and positive Borrelia serology.
Pathologic examination was typical for acrodermatitis chronica
atrophicans, a late skin manifestation of Lyme borreliosis. In
all patients, symptoms improved after treatment with doxycycline
for four weeks. A lack of familiarity with this skin condition
may lead to unnecessary vascular investigations and considerable
delay in adequate treatment.

Excerpt:

Common gut bacteria can induce eukaryotic chromosomal instability in vivo, according to a study published in a recent issue of the Proceedings of the National Academy of Sciences USA.Up to 34% of commensal Escherichia coli strains isolated from human faeces in high-income countries contain pks, a genomic island encoding a cluster of non-ribosomal peptide synthetases and polyketide synthetases that are involved in the production of the genotoxin colibactin.