31 March 2009

MRSA news from Europe - Society for General Microbiology

The annual meeting of the UK's Society for General Microbiology is taking place this week, so here's a quick roundup of MRSA-related news. As with these posts from a year ago, abstracts are not online; in a few cases there are press releases from the science-news service EurekAlert.
  • MRSA-colonized patients who have been identified in a hospital by active surveillance culturing may not need to be isolated to prevent their bacteria being transmitted to other patients by healthcare workers — provided hospital staff and visitors adhere to very vigorous handwashing. (P. Wilson, University College Hospital, London; press release)
  • An engineered coating made of titanium dioxide with added nitrogen could be employed as an antibacterial surface in hospitals; exposure to ordinary white light activates the compound to kill E. coli and may be useful against MRSA also. (Z. Aiken, UCL Eastman Dental Institute; press release)
  • The natural antiseptics tea tree oil and silver nitrate enhance bacterial killing when combined, which may also allow them to be used in lower doses – important for avoiding toxicity. It may also be possible to deliver them encapsulated in engineered sphere made of lipids called liposomes. (W.L. Low, University of Wolverhampton; press release)
  • Overuse of antibiotics in farming is not only breeding resistant bugs in animals, it is also changing soil ecology and depleting nitrogen-fixing bacteria that improve soil fertility. The antibiotics are affecting soil when manure from drug-using farms is spread as fertilizer. (H. Schmitt, University of Utrecht; press release)

1 comment:

daedalus2u said...

I think that the soil bacteria being talked about that are part of the nitrogen cycle are ammonia oxidizing bacteria, not nitrogen fixing bacteria. I wasn’t able to find the paper mentioned on line, but I did find her thesis.


The effects of toxicants on nitrification are a standard test. The ammonia oxidizing bacteria are slow to recover because they are quite slow growing, optimum doubling times of ~10 hours.

Pig waste slurry is high in ammonia, so nitrogen fixing bacteria are not needed in those soils. In the absence of nitrification, high levels of ammonia can build up, and since ammonia is held as a cation by soil cationic ion exchange sites (where nitrate as an anion is mobile), nitrification is important in redistributing nitrogen in the soil.

I think that inhibition of nitrifying bacteria is the reason that antibiotics work to increase the weight gain, speed of maturity and efficiency of converting feed to biomass in farm animals. They cause low NO which shifts physiology to a more androgenic state, the state of “high stress”. I think bathing is doing the same things to humans that antibiotics in animal feed does to farm animals animals. Makes them big and fat and reach puberty sooner.