Some Thoughts on the CRE ‘Superbugs’

Last week, you might have read about carbapenem-resistant ‘superbugs’ (actually, these are pretty ordinary bacteria except that they’re resistant to just about everything we can throw at them) due to the recent study detailing an outbreak at the NIH. I’ve written about these organisms before, so I won’t rehash the biology.

(full disclosure: I am currently involved with an NIAID-funded project to sequence isolates (historical and prospectively isolated) from multiple hospitals.)

Right now, the only good news is that these infections are still very rare–on the East Coast, outside of New York City, large hospitals are maybe seeing one per month (in some NYC hospitals, they’re more common). While they are spreading, they are still essentially anecdotal events. Sometimes, they’re associated with an outbreak (i.e., more than one patient), other times, they appear to be ‘one offs.’ What is disconcerting is that, increasingly, these isolates can’t be traced back to New York. And as Maryn McKenna notes, because these organisms are commensals (part of the normal gut flora), they can be carried by asymptomatic people.

Right now, I think we can still contain this organism if hospitals practice really rigorous infection control (isolating patients, testing surfaces, and screening workers), although Klebsiella pneumoniae is a very hardy organism (at the NIH hospital, it was found in the sink drains). Unfortunately, I don’t think there is the political will or the public health infrastructure to respond adequately to this crisis.

Cataloging the apocalypse is getting really old.

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5 Responses to Some Thoughts on the CRE ‘Superbugs’

  1. dr2chase says:

    So how are these bugs persisting in sink drains? Would a daily drizzle of bleach do the job? Suppose they just enhanced the water with a little bleach, in the same way that we do for stored water supplies? Or how about hanging a hard-UV light under the spigot, aimed down at the drain, with a motion sensor to disable when a human was at the sink?

    Is it possible that continuous exposure to something less hard than UVC would get the job done (because UVC LEDs are not at all cheap, 405-470nm kills MRSA, and blue (470nm) and royal-blue (450nm) 1-watt LEDs cost $5, quantity 1). Says here that 55J/cm^2 killed 90% of the MRSA; figure a drain area of 45 cm^2, about .5W out of a 1W royal blue LED, 1.5 minutes = 90 seconds = 45J. Does this evolve a blue-resistant MRSA? Sounds like someone needs to study this :-).

    And I’m curious — if I run a blue LED up my nose and leave it there for a few minutes, does that wipe out the commensal staph that may or may not be hanging out up there? And is this a good thing?

  2. bad Jim says:

    Forgive me if this has been brought up before, but mightn’t specific “superbugs” be good targets for bacteriophages? If a phage preparation is available (perhaps a big if) then a quick DNA assay of the suspected infectious agent could lead to its expeditious use, rather than the laborious culturing required for unknown bacteria.

    To the extent that phages are otherwise benign, and also unlikely to lead to resistance, another pair of big ifs, perhaps a cocktail of antagonists to the most common resistant bacteria could be routinely employed.

  3. Pingback: Genomic Epidemiology Is Not a Panacea, But It Will Be Very Useful | Mike the Mad Biologist

  4. sciliz says:

    dr2chase- undoubtably there are ways of eradicating them from drains, but drains are kinda notorious for biofilms so it’s not trivial. UV-kills-it-in-a-newish-monolayer is not the same as UV-kills-it-in-situ. Of course, if you are *keeping* an already clean drain clean, it could work!

    bad Jim- far too often, being able to detect an organism from e.g. environmental swabs with PCR actually relies on laborious culturing steps (in enrichment broth) anyway. Now, blood and other clinical/patient samples are another matter for detection purposes, but using phages internally in people is problematic for many reasons (my favorite being the “zombie E. coli” hypothesis spun by a grad student friend; basically, he found out that there are ways in which a tiny amount of pathogenic O157H7 E coli with phage can turn a large number of commensal E. colis into phage producers. His stuff is all in vitro, but it’s made me REALLY wary of using bacteriophage therapy in vivo, especially in cases where there are large populations of commensal that are naturally around, like for MRSA.). I have heard there are some inroads being made with phages and MRSA, but my understanding is that part of the appeal is that topic application might be reasonable for some wounds.
    And phages will lead to resistance- google CRISPR for some fascinating stuff on bacterial ‘adaptive’ immunity.

  5. Art says:

    One story had the hospital replacing sinks in an attempt to eliminate a possible source for infection. Having worked on the physical plant side of a hospital I wonder how they did the replacement. Plumbers aren’t known for their strict infection control practices and they themselves could easily become carriers.

    Also the logistics of construction, like how do you transport them through the hospital, are going to run counter to good infection control practices. I’ve seen construction debris moved through clean areas uncovered when nobody bothered to address the issues. Then, once you have them outside what do you do with those sink. Do you just toss them into a dumpster? There are typically lots of scroungers around major institutions. If they see a ‘perfectly good’ sink in the trash there are good odds it will end up across town being sold for scrap, or resold on Craig’s List, or installed in their aunties house. Is it better to try to decontaminate it or do you put it under armed escort all the way to the blast furnace where it gets melted down?

    I seem to remember a proposed design, from the 50s I presume, for a self-sterilizing operating room that featured a cobalt-60 radiation source that would be lowered into the middle of the room to blast it with hard radiation. I assume they included some sort of fail-safe interlocks on the doors and some sure-fire way to make sure the Co-60 was safely returned to its shielded container. It would be a bitch to have to draw straws to see who gets to put the radiation source away manually. Those sorts of practical amenities save a lot of wear and tear on the staff.

    That is kind of extreme, and probably grossly impractical, and I only bring it up to illustrate how desperate things could get, but we are rapidly running out of attractive options and crude Soviet-style brute force technology may be what we are left with.

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