Nasal decolonization of Staphylococcus aureus with mupirocin: strengths, weaknesses and future prospects

Staphylococcus aureus in the nose is a risk factor for endogenous staphylococcal infection. UK guidelines recommend the use of mupirocin for nasal decolonization in certain groups of patients colonized with methicillin-resistant S. aureus (MRSA). Mupirocin is effective at removing S. aureus from the nose over a few weeks, but relapses are common within several months. There are only a few prospective randomized clinical trials that have been completed with sufficient patients, but those that have been reported suggest that clearance of S. aureus from the nose is beneficial in some patient groups for the reduction in the incidence of nosocomial infections. There is no convincing evidence that mupirocin treatment reduces the incidence of surgical site infection. New antibiotics are needed to decolonize the nose because bacterial resistance to mupirocin is rising, and so it will become less effective. Furthermore, a more bactericidal antibiotic than mupirocin is needed, on the grounds that it might reduce the relapse rate, and so clear the patient of MRSA for a longer period of time than mupirocin

A review and preliminary evaluation of methodological factors in performance assessments of time-varying aircraft noise effects

The effects of aircraft noise on human performance is considered. Progress is reported in the following areas: (1) review of the literature to identify the methodological and stimulus parameters involved in the study of noise effects on human performance; (2) development of a theoretical framework to provide working hypotheses as to the effects of noise on complex human performance; and (3) data collection on the first of several experimental investigations designed to provide tests of the hypotheses

Worldwide time and frequency synchronization by planned VLBI networks

Accurate baseline determinations and clock synchronization results obtained from the Quasar Patrol observations at X band with the Goldstone-Haystack baseline are presented. In addition, data from stations at Greenbank, West Virginia, and Onsala, Sweden were used. It was estimated that clock accuracy was on the order of 16 cm

Mega-Events: Is the Texas-Baylor game to Waco what the Super Bowl is to Houston?

This paper estimates the total sales and sales tax revenue impacts on host communities of a variety of professional and collegiate sporting events. Using 126 jurisdictions from Texas, covering every month from January, 1990 through April of 2006, the analysis finds that regular season games in the NBA, NFL, NHL, and MLB have widely disparate effects. The NBA and NFL regular season games are net losers of revenue, NHL and MLB games generate additional revenue. Collegiate regular season football games are revenue generators for small cities and towns home to D-I and D-IAA football, but cities that are home to teams from the old Southwest Conference or the new Big 12 conference do not gain revenues from home contests. The Super Bowl generated over $2 million in tax revenues for Houston, by far the largest revenue boost of any of the events in our data.tourism, economic impacts, special events

Shape oscillations of human neutrophil leukocytes: characterization and relationship to cell motility

When neutrophil leukocytes are stimulated by chemotactic factors or by substratum contact, they change their shape. Shape changes are a prerequisite for cellular migration and typically involve the extrusion of thin, veil-like lamellipods and the development of morphological polarity. Stimulation also leads to changes in the neutrophil content of filamentous actin (F-actin), which is the major cytoskeletal component. Suspensions of human neutrophils stimulated with chemoattractants exhibit sinusoidal light-scattering oscillations with a period of approximately 8 s at 37°C. These oscillations arise from periodic fluctuations in the cell body size caused by lamellipod extension and retraction cycles. The light-scattering oscillations are paralleled by corresponding oscillations in F-actin content. This raises the interesting possibility that cyclic actin polymerization constitutes the driving force for shape oscillations of suspended neutrophils. Similar periodic shape changes are present in neutrophils crawling on a surface, suggesting that shape oscillations are important for neutrophil motion. This review summarizes our present knowledge about shape oscillations in suspended and crawling neutrophils and discusses a possible role for these oscillations in neutrophil motility

Effect of Different Media on the Bactericidal Activity of Colistin and on the Synergistic Combination With Azidothymidine Against mcr-1-Positive Colistin-Resistant Escherichia coli

Antimicrobial susceptibility testing (AST) performed according to defined guidelines is important to identify resistance and to predict the clinical success or failure of specific antibiotic therapy. However, these guidelines do not cover all physiological conditions that can have a tremendous impact on in vivo resistance. In this study, we tested the susceptibility of thirteen mcr-1-positive Escherichia coli strains against colistin, one of the last resort antibiotics for treating multi-drug resistant pathogens, in media recommended for ASTs as well as – physiologically more relevant – in human serum and artificial urine (AU). Minimal inhibitory concentration (MIC) values in heat-inactivated human serum were similar to those in cation-adjusted Mueller-Hinton broth (CAMHB), but reduced in native serum for almost all strains that could grow in this media. In AU MIC values for mcr-1 positive E. coli were increased significantly up to 16-fold compared to that in CAMBH, which did not apply to the colistin-susceptible E. coli strains tested. Although different growth media could affect the MIC of colistin alone, their impact on the synergistic effect of the combination with the antiviral drug azidothymidine was minimal. The higher divalent cation concentration combined with acidic pH values is most likely responsible for the increased MIC values of the mcr-1 harboring E. coli strains tested against colistin in AU compared to that in CAMHB. Antimicrobial susceptibility screening procedures for colistin using CAMHB only could lead to an underestimation of resistance under different physiological conditions. Therefore, not only pharmacokinetic but also pharmacodynamic studies in urine are as important as in serum or plasma

Transposon and deletion mutagenesis of genes involved in perchlorate reduction in Azospira suillum PS.

UnlabelledAlthough much work on the biochemistry of the key enzymes of bacterial perchlorate reduction, chlorite dismutase, and perchlorate reductase has been published, understanding of the molecular mechanisms of this metabolism has been somewhat hampered by the lack of a clear model system amenable to genetic manipulation. Using transposon mutagenesis and clean deletions, genes important for perchlorate reduction in Azospira suillum PS have been identified both inside and outside the previously described perchlorate reduction genomic island (PRI). Transposon mutagenesis identified 18 insertions in 11 genes that completely abrogate growth via reduction of perchlorate but have no phenotype during denitrification. Of the mutants deficient in perchlorate reduction, 14 had insertions that were mapped to eight different genes within the PRI, highlighting its importance in this metabolism. To further explore the role of these genes, we also developed systems for constructing unmarked deletions and for complementing these deletions. Using these tools, every core gene in the PRI was systematically deleted; 8 of the 17 genes conserved in the PRI are essential for perchlorate respiration, including 3 genes that comprise a unique histidine kinase system. Interestingly, the other 9 genes in the PRI are not essential for perchlorate reduction and may thus have unknown functions during this metabolism. We present a model detailing our current understanding of perchlorate reduction that incorporates new concepts about this metabolism.ImportanceAlthough perchlorate is generated naturally in the environment, groundwater contamination is largely a result of industrial activity. Bacteria capable of respiring perchlorate and remediating contaminated water have been isolated, but relatively little is known about the biochemistry and genetics of this process. Here we used two complementary approaches to identify genes involved in perchlorate reduction. Most of these genes are located on a genomic island, which is potentially capable of moving between organisms. Some of the genes identified are known to be directly involved in the metabolism of perchlorate, but other new genes likely regulate the metabolism in response to environmental signals. This work has uncovered new questions about the regulation, energetics, and evolution of perchlorate reduction but also presents the tools to address them

Structure and evolution of chlorate reduction composite transposons.

UnlabelledThe genes for chlorate reduction in six bacterial strains were analyzed in order to gain insight into the metabolism. A newly isolated chlorate-reducing bacterium (Shewanella algae ACDC) and three previously isolated strains (Ideonella dechloratans, Pseudomonas sp. strain PK, and Dechloromarinus chlorophilus NSS) were genome sequenced and compared to published sequences (Alicycliphilus denitrificans BC plasmid pALIDE01 and Pseudomonas chloritidismutans AW-1). De novo assembly of genomes failed to join regions adjacent to genes involved in chlorate reduction, suggesting the presence of repeat regions. Using a bioinformatics approach and finishing PCRs to connect fragmented contigs, we discovered that chlorate reduction genes are flanked by insertion sequences, forming composite transposons in all four newly sequenced strains. These insertion sequences delineate regions with the potential to move horizontally and define a set of genes that may be important for chlorate reduction. In addition to core metabolic components, we have highlighted several such genes through comparative analysis and visualization. Phylogenetic analysis places chlorate reductase within a functionally diverse clade of type II dimethyl sulfoxide (DMSO) reductases, part of a larger family of enzymes with reactivity toward chlorate. Nucleotide-level forensics of regions surrounding chlorite dismutase (cld), as well as its phylogenetic clustering in a betaproteobacterial Cld clade, indicate that cld has been mobilized at least once from a perchlorate reducer to build chlorate respiration.ImportanceGenome sequencing has identified, for the first time, chlorate reduction composite transposons. These transposons are constructed with flanking insertion sequences that differ in type and orientation between organisms, indicating that this mobile element has formed multiple times and is important for dissemination. Apart from core metabolic enzymes, very little is known about the genetic factors involved in chlorate reduction. Comparative analysis has identified several genes that may also be important, but the relative absence of accessory genes suggests that this mobile metabolism relies on host systems for electron transport, regulation, and cofactor synthesis. Phylogenetic analysis of Cld and ClrA provides support for the hypothesis that chlorate reduction was built multiple times from type II dimethyl sulfoxide (DMSO) reductases and cld. In at least one case, cld has been coopted from a perchlorate reduction island for this purpose. This work is a significant step toward understanding the genetics and evolution of chlorate reduction

Qualitative and quantitative analysis of saliva in a group of HIV infected individuals

A study which investigates whether the quality and quantity of saliva may contribute to the prevalence of oral disease in HIV infection, and whether there is a significant variance of saliva quality and quantity between early and late stage HIV infection. Samples were collected from 65 subjects with HIV infection and 33 control subjects. Results indicate that it is more likely that subjects with HIV infection will have reduced stimulated salivary flow than subjects without HIV, and that this reduction is not related to the stage of HIV infection nor to medication taken. Subjects with low salivary pH were more likely to exhibit candidiasis.Thesis (M.D.S.) -- University of Adelaide, Dept. of Dentistry, 199