The epidemiology of enterococci

The enterococci are emerging as a significant cause of nosocomial infections, accounting for approximately 10 % of hospital acquired infections. They are found as normal inhabitants of the human gastrointestinal tract, but may also colonize the oropharynx, vagina, perineal region and soft tissue wounds of asymtomatic patients. Until recently, evidence indicated that most enterococcal infections arose from patients' own endogenous flora. Recent studies, however, suggest that exogeneous acquisition may occur and that person-to-person spread, probably on the hands of medical personnel, may be a significant mode of transmission of resistant enterococci within the hospital. The use of broad-spectrum antibiotics, especially cephalosporins, is another major factor in the increasing incidence of enterococcal infections. These findings suggest that barrier precautions, as applied with other resistant nosocomial pathogens, along with more judicial use of antibiotics may be beneficial in preventing nosocomial spread of resistant enterococci.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47899/1/10096_2005_Article_BF01963631.pd

Organization of Nucleotides in Different Environments and the Formation of Pre-Polymers

RNA is a linear polymer of nucleotides linked by a ribose-phosphate backbone. Polymerization of nucleotides occurs in a condensation reaction in which phosphodiester bonds are formed. However, in the absence of enzymes and metabolism there has been no obvious way for RNA-like molecules to be produced and then encapsulated in cellular compartments. We investigated 5′-adenosine monophosphate (AMP) and 5′-uridine monophosphate (UMP) molecules confined in multi-lamellar phospholipid bilayers, nanoscopic films, ammonium chloride salt crystals and Montmorillonite clay, previously proposed to promote polymerization. X-ray diffraction was used to determine whether such conditions imposed a degree of order on the nucleotides. Two nucleotide signals were observed in all matrices, one corresponding to a nearest neighbour distance of 4.6 Å attributed to nucleotides that form a disordered, glassy structure. A second, smaller distance of 3.4 Å agrees well with the distance between stacked base pairs in the RNA backbone, and was assigned to the formation of pre-polymers, i.e., the organization of nucleotides into stacks of about 10 monomers. Such ordering can provide conditions that promote the nonenzymatic polymerization of RNA strands under prebiotic conditions. Experiments were modeled by Monte-Carlo simulations, which provide details of the molecular structure of these pre-polymers