Osteomyelitis: most common pathogen

[DrMetal]

was reading the section on Osteomyelitis, on pg. 204 of Step Up to USMLE Step 2: it mentions that the most common cause is Staph Aureus , but that in the case of sickle cell disease or IV drug abuse, one should also consider Salmonella and Pseudomonas (respectively) as the causal pathogen.

In the margin note, it states that although there's an association between Salmonella/Pseudomonas for osteomyelitis in the setting of SCD/IVDA (respectively), that the "most common" pathogen (even in these patient sub groups) is Staph Aureus.

Is this really true? So if I get a question that paints a beautiful picture of SCD or IVDA (with all of the clinical manifestations, lab abnormalities, etc etc) and osteomyelities . . .if asked, what's the most likely causal organism, the correct answer is Staph Aureus??? (regardless of the association mentioned above)

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[SirGecko]

Staph aureus is most common. That said I imagine if they wanted to test the association with salmonella or psuedomonas they'd ask you which bugs you need to cover for or something like that.

 

[ijn]

It's true. If you have to choose between S. aureus and one of the other bugs when given no other information, then go with S. aureus.

The question writers can slice this apple a million different ways. If they tell you about a kid who steps on a nail, the most common bug is actually Pseudomonas. That fact has been tested before.

Regardless, you treat empirically until you get a culture.

Staph aureus is most common. That said I imagine if they wanted to test the association with salmonella or psuedomonas they'd ask you which bugs you need to cover for or something like that.

I think it's more likely that they'd omit S. aureus as an answer choice if they want you to answer Salmonella for a kid with sickle cell, or Pseudomonas for a diabetic.

 

[DrMetal]

Ok thanks, just wanted to make sure I was reading that right.

 

[ASAPRocky]

Ok thanks, just wanted to make sure I was reading that right.

you were.

 

[Transposony]

Salmonella is the second most common organism that causes osteomyelitis in patients with sickle
cell disease and should always be considered in these patients.