MRSA and bedbugs?

An ahead-of-print paper in Emerging Infectious Diseases is generating some buzz in the mainstream media. While the findings are interesting, I’m honestly not sure how they got published, being so preliminary.

Like many areas, Vancouver, British Columbia has seen a jump in the prevalence of bedbugs. After finding impoverished patients infested with the bugs, researchers decided to collect some and test them for pathogens–specifically, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). So, they tested 5 bugs from 3 patients. That’s it–it doesn’t even appear to be 5 bugs apiece, but just 5 total. And the bugs were simply homogenized and streaked–not an uncommon way to test bugs for microbes, but one that has pretty severe limitations if you’re really looking at transmission via biting.

They did find MRSA (and VRE)–obviously, or it wouldn’t have made news. VRE was isolated from 1 bug each from 2 patients; MRSA was isolated from 3 bedbugs from the remaining patient. At first read, I thought they’d confirmed the MRSA strains were USA300, but they didn’t even do that–all they did was note the antibiotic susceptibility profiles of the isolates were consistent with USA300 (though headlines are already screaming “flesh eating bacteria isolated from bedbugs!” as you can see from the link up top). However, what we don’t know if whether the bedbugs were simply externally contaminated (perhaps from close contact with their human hosts), or if they were actually carrying the organisms in their salivary glands (as has been previously reported for S. aureus). If it’s the latter, an infection risk seems more plausible, although I suppose a bite from an externally-contaminated bedbug could also introduce organisms into an open wound.

Still, the paper is really, really, really sparse on data. I’ll sum up with words expressed in the newspaper story above:

Medical health officer Dr. Reka Gustafson said the St. Paul’s study is so small that no public health warning is necessary. She noted the superbug MRSA can be found on “doctors’ ties” and chairs in public places and that it’s more important to counsel people “to wash their hands thoroughly and use antibiotics wisely.”

Lowe CF, Romney MG (2011). Bedbugs as Vectors for Drug-Resistant Bacteria Emerging Infectious Diseases

Comments

  1. #1 Rosie Redfield
    May 12, 2011

    The patients were infested with bedbugs? I thought bedbugs only visited the host transiently, at night, to bite, and then crept back to wherever they hide during the day. Did they collect the bedbugs from the patients at the hospital? Is St. Paul’s Hospital now infested with bedbugs?

  2. #2 Tara C. Smith
    May 12, 2011

    Yeah, I had questions about that too. I don’t know how long they remain attached to the human. I know they can also be transmitted in clothes/luggage, but again don’t know how long they may remain attached to that either. It does appear the bedbugs were collected at the hospital. I emailed the corresponding author and perhaps he will chime in.

  3. #3 J.A. Ginsburg
    May 14, 2011

    Hey Tara,

    What struck me most about the study was that *anything* was found given such a small sample. I certainly hope some larger studies will follow. Even if it turns out bedbugs don’t play a big role in infection, do they play a role in spread? The numbers of pesticide-resistant bedbugs has exploded across the continent in just a few years. I would love to see a map of bed bug spread / concentration overlaid against of a map of MRSA / VRE cases… In the meantime, the “TrackerNews” companion editior’s blog now has its own companion blog: “Dot to Dot” – thought you might find this post interesting: http://trackernews-dot-to-dot.posterous.com/52969345

  4. #4 Tara C. Smith
    May 16, 2011

    I’m not so surprised. They took them from individuals at a hospital in an area with an extremely high MRSA prevalence–not a much better way to find MRSA. I agree that larger studies are needed, and thanks for the link to the new blog!

  5. #5 Terri
    May 16, 2011

    The report is clear that this does not mean bed bugs are carrying the disease from human to human via feeding but may just offer an opportunity for MRSA to be present on the victim and the scratching from bed bug reactions can create an entry point. However, many perceive this as hype when in fact, the media UNDERreports bed bug infestations. The bottom line is, do what you can to avoid bed bugs! I found Greenbug for People that kills and repels bed bugs and think it is the best so I am posting for them. I will never travel without Greenbug – ever!

  6. #6 Stephen
    May 17, 2011

    Bed bugs appear to be on the rise, at least from anecdotal stories locally. Bed bugs are bad enough. Bed bugs with MRSA is a horror movie in the making.

    My son found a baseball cap left at a scouting picnic. My wife discovered it has lice (fortunately, no one put it on). But who’d a thunk it?

    I did hear a hopeful MRSA story, though. There are viruses (phages) that infect Staphylococcus aureus, and can kill it, and which are totally harmless to humans. And unlike an anti-biotic, a virus could beat SA in an arms race. We just need to do the science and get the FDA on board. I think the science bit is easier.

  7. #7 Superbug
    May 31, 2011

    it would be nice to see larger studies confirming this study because if it is true about the bed bugs it would be nice to know for sure so we all can take the necessary precautions.

    Also did the author ever respond to your email?