September 1st, 2010

Testing your Testing Skills

questionHave I whined yet about how I’m part of the first Internal Medicine class that was not “grandfathered” through to eternal board certfication? 

If not, now I have.

So for you fellow test-takers, here’s another one for you, adapted somewhat from this delightful experience I’m required to go through every 10 years.  Oddly, just like the last one reviewed here, it involves our old friend, MRSA.

18 year old kid scrapes his knee playing a sport, comes in with infection around injury.  No purulence.  Community MRSA is  known to be in the community.  What should you give him?

  1. azithromycin
  2. cephalexin
  3. dicloxacillin
  4. trimethoprim-sulfamethoxazole

Every so often one encounters a test question that is, frankly, just wrong.  But in the often-bizarre world of “let’s pretend” patient care — a test question — you still have to put your money down.

So what’s the answer?

4 Responses to “Testing your Testing Skills”

  1. Jon says:

    Paul, this seems more an existential rather than a boards question. I’m guessing they want you to choose #4, but if there’s no purulence/abscess and the infection is not particularly severe, most providers would probably give keflex or dicloxacillin. Both have much better Strep activity and are active against MSSA.

  2. Justin says:


    So your medical board registration is dependent on answering this question? Rough…

    Yes, the comment about MRSA being ‘in the community’ actually makes the question more ambiguous without any knowledge of how prevalent it is. Maybe in Tonga the prevalence is high enough that you would treat empirically regardless, but, as Jon says, for a non-severe infection in less prevalent areas I think most wouldn’t.

    That’s without even getting into increasing rates of bactrim resistance in many areas… or maybe we’re over-thinking this one!

  3. todd ellerin says:

    I think the answer is we don’t know exactly what to do in these cases of cellultis without purulent infection.Prior to CA MRSA, it didn’t matter what we chose since diclox and
    cephalexin covered both strep and meth-sens Staph.Now,in the era of CA MRSA we know we have to direct therapy against MRSA when pts present with abscesses a/w cellulitis and Bactrim,doxy, clinda are the go to abxs. But for cases of cellulitis w/o abscess we don’t know the proportion that are caused by MRSA.I think the preactice in the community is to use cephalexin or diclox with or without Bactrim. Some providers may use Bactrim alone but as the last discussant noted Bactrim has poor strep activity and doxy is not necessarily reliable either. Clinda has realiable strep and most ca MRSA strains are still sensitive but the spectre of C diff makes us think twice about this agent. The other question is whether post traumatic cellulitis has a greater likelihood of Staph cellulitis than spontaneous cellulitis and I don’t know the answer to this but suspect it may. Back to the question, azithromycin is the only wrong choice since even MSSA is becoming inceasingly resistant to macrolides/azalides never mind MRSA which is almost uniformly resistant to macrolides. I don’t see any difference b/w diclox and cephalexin even though there may be some very subtle differences with respect to activity in the face of certain beta lactamases so the creator of this question must want us to choose Bactrim monotherapy but besides choice A being wrong the only thing I know is that we do not know exacty what to do in this case. Lastly, we shouldn’t lose too much sleep over this question b/c studies looking at CAMRSA abscesses and initial choice of abxs conclude that pts overall do well even if you start with the wrong abx initially!

  4. Anne says:

    I am not a doctor, I am a test developer. Having exactly zero knowledge about the content here (could be Chinese to me), but based solely on the structural design of multiple-choice items, I would venture to guess that the correct answer (the “key” in testing parlance) is #4. I say this merely because it is significantly longer than the other three options (the “distractors”) and therefore leads one to believe that it contains the best information. If the length of another option were similar to number 4, my guess would have been totally random. Was I correct? If so, here’s another reason why this is not a good question!

HIV Information: Author Paul Sax, M.D.

Paul E. Sax, MD

Contributing Editor

NEJM Journal Watch
Infectious Diseases

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