02 October 2008

Non-pharm prevention alternative for MRSA skin infections

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.


Robyn said...

No, I have no financial connection to commercial herbal products nor pharmaceutical products.

For further reading, look up how Oregon grape root protects itself from Staphylococcus. Clever plant. No surprise after million years of testing.

Thanks for following this up, Maryn.

daedalus2u said...

Many things that are considered non-antibiotics still cause the development of antibiotic resistance. Even things like pine oil. It causes the up regulation of the multi-drug transporter which organisms use to export antibiotics. Antibiotic resistance through that mechanism tends to be very broad spectrum.

What most organisms in the wild do to prevent growth of biofilms and infections on their surfaces is to disrupt quorum sensing by target microorganisms. In the ocean, the halogen reductases generate hypochlorite which oxidizes the quorum sensing compounds and suppresses quorum sensing.

Plants release compounds in their roots to favor commensal organisms and suppress pathogens. An important class of commensal organisms are the ammonia oxidizing bacteria which oxidize ammonia into nitrite and NO. NO is a quorum sensing compound that organisms use to switch from planktonic to the biofilm phenotype. Low NO triggers that switch in some infectious agents (Pseudomonas and Staph for example). At high NO levels they never form a biofilm. A biofilm is one of the major virulence factors. Bacteria in a biofilm are hundreds of times more resistant to antibacterial agents.

(I do have a commercial interest in the development and use of topical ammonia oxidizing bacteria including to prevent and treat surface infections the theory of which I have written up here http://daedalus2u.blogspot.com/2008/06/suggestion-to-reduce-antibiotic.html )