Maryn McKenna

Journalist and Author

MRSA news from Europe – Society for General Microbiology

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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)

Non-pharm prevention alternative for MRSA skin infections

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Longtime reader and botanical-medicine expert Robyn spotted this new story and study this morning and pointed it out in the comments to a previous post. It’s about a product, but it’s a product with science to back it, so under my rules regarding commercial products, I am moving it up to post status. (Robyn didn’t say, but given the internals of her post I assume, that she has no commercial interest in this. Right, Robyn?)

The product under investigation is an over-the-counter cream called StaphASeptic that contains the natural antimicrobials tea tree (Melaleuca alternifolia) oil and white thyme (Thymus vulgaris — the “white” refers to the preparation not the species) oil, along with the commercial antiseptic benzethonium chloride. That product’s effect on isolates of CA-MRSA was compared against two common OTC first aid creams, one containing the topical antibiotic polymyxin B and the other containing both polymyxin B and the topical antibiotic neomycin.

The authors found that the botanical-containing cream did a better job of killing CA-MRSA in a time-kill analysis, finding specifically that it went on killing longer — up to 24 hours — than the other two creams. The assumption obviously is that this non-antibiotic cream would do a better job of protecting superficial wounds and scrapes from MRSA infection than the antibiotic-containing ones, while presumably not promoting resistance.

But the important question, which Robyn raises, is whether the essential oils are not in fact acting as natural antibiotics, possibly synergistically. Let’s remember that the majority of antibiotics — including, for instance MRSA drug-of-last-resort vancomycin, and its replacement daptomycin — were initially isolated from natural substances (fungi, in both those cases). Overall, however, botanical products receive much less research attention that pharmaceuticals, so their action and their therapeutic potential remain unexplored.

The cite is: Bearden, DT, Allen GP and Christensen JM. Comparative in vitro activities of topical wound care products against community-associated methicillin-resistant Staphylococcus aureus. Journal of Antimicrobial Chemotherapy (2008) 62, 769–772. NB: The research was supported by an unrestricted grant from StaphASeptic ‘s manufacturers, Tec Laboratories Inc., and JM Christensen, of the Oregon State University College of Pharmacy, disclosed a consultant relationship with Tec.