Inhibition of Yersinia pestis DNA adenine methyltransferase in vitro by a stibonic acid compound: identification of a potential novel class of antimicrobial agents.

BACKGROUND AND PURPOSE: Multiple antibiotic resistant strains of plague are emerging, driving a need for the development of novel antibiotics effective against Yersinia pestis. DNA adenine methylation regulates numerous fundamental processes in bacteria and alteration of DNA adenine methlytransferase (Dam) expression is attenuating for several pathogens, including Y. pestis. The lack of a functionally similar enzyme in humans makes Dam a suitable target for development of novel therapeutics for plague. EXPERIMENTAL APPROACH: Compounds were evaluated for their ability to inhibit Dam activity in a high-throughput screening assay. DNA was isolated from Yersinia grown in the presence of lead compounds and restricted to determine the effect of inhibitors on DNA methylation. Transcriptional analysis was undertaken to determine the effect of an active inhibitor on virulence-associated phenotypes. KEY RESULTS: We have identified a series of aryl stibonic acids which inhibit Dam in vitro. The most active, 4-stibonobenzenesulfonic acid, exhibited a competitive mode of inhibition with respect to DNA and a K(i) of 6.46 nM. One compound was found to inhibit DNA methylation in cultured Y. pestis. The effects of this inhibition on the physiology of the cell were widespread, and included altered expression of known virulence traits, including iron acquisition and Type III secretion. CONCLUSIONS AND IMPLICATIONS: We have identified a novel class of potent Dam inhibitors. Treatment of bacterial cell cultures with these inhibitors resulted in a decrease in DNA methylation. Expression of virulence factors was affected, suggesting these inhibitors may attenuate bacterial infectivity and function as antibiotics.

Prescribing of oral nutritional supplements in Primary Care: can guidelines supported by education improve prescribing practice?

BACKGROUND AND AIMS: With increasing resources being spent on nutritional supplements, this study sought to evaluate the effect of introducing guidelines on prescribing of supplements, by auditing practice, prior to, and after the implementation of guidelines. METHODS: Prescribing practice was evaluated from patient interviews, and knowledge of health professionals examined from questionnaires from 50 GP practices. Training on the use of guidelines on prescribing supplements was implemented, incorporating a Nutritional Screening Tool and practical application of high-energy dietary advice, targeting GPs and Community Nurses. RESULTS: Education to GPs and Community Nurses significantly reduced total prescribing by 15% and reduced the levels of inappropriate prescribing from 77% to 59% due to an improvement in monitoring of patients prescribed supplements. Although knowledge regarding high-energy dietary advice for nutritionally 'at risk' patients did improve as a result of the training, this was not demonstrated in practice. This lack of relevant dietary advice remained the main reason that inappropriate supplement prescriptions remained high. CONCLUSION: Education on guidelines incorporating a Nutritional Screening Tool has proved to be an effective method of achieving more appropriate prescribing of supplements, suggesting the need for ongoing training of health professionals in Primary Care.