So we're confident in our diagnosis.
Here's one important point though,
even though his gram stain was negative, which
may have been what could have steered you away
from non-gonococcal septic arthritis,
don't hang your hat on just the gram stain.
We need to wait for the culture to come back.
In the meantime, we're absolutely gonna start
antibiotics while waiting for that culture to come back.
In terms of thinking about the initial treatment
and which antibiotics to use, the bacteria that cause
the bacteria that cause non-gonococcal septic joint
are Staph. aureus, Staph. aureus and Staph. aureus.
Yes there are some other
organisms that can cause it,
absolutely you may see gram negative
organisms, you may see streptococcus
but Staph is gonna be
your most likely agent.
And because of that, we have a very
low threshold to put on vancomycin to treat
potentially methicillin-resistant Staph.
aureus which is increasingly common.
So looking at this
algorithm, starting at the top,
if you have results on the gram stain: gram positive
cocci or gram negative rods, that may steer you.
But if it's negative, you just automatically
presume you're gonna have Staph
and start somebody on Vancomycin.
If the gram stain is positive, then you
can make a bifurcation here on the road
if you clearly see gram positive
cocci, obviously you'll start Vancomycin.
If you clearly see gram negative rods alone, then
you're thinking about E.coli, Serratia, Klebsiella, etcetera
then it's okay to specifically
treat with Ceftriaxone
while awaiting further speciation
of your microbial cultures.
So, again management:
You're gonna obtain the blood cultures, start
antibiotics while waiting for more information.
Once you get more information from the
culture data, you can narrow your antibiotics.
You may need to perform serial aspirations.
This is often the case if there is a real septic joint, you
may want to confirm that the infection has fully resolved
especially if you're talking
about hardware or prosthetic joint.
And if need be, you can get
Infectious Disease on board as well,
because the management of prosthetic
joints can be particularly challenging.
Okay, so let's highlight a few key points.
Acute monoarticular arthritis
is the classic presentation
for non-gonococcal arthritis and
the knee is the most common.
Look for risk factors: injection drug
use, sickle cell disease, prosthetic joints
getting an ID consult.
and any recent surgery that
could've made the patient bacteremic
You're looking for a large effusion.
it should be a hot, inflamed joint.
and certainly your polymorphonuclear
cells would really be above 50,000
unless for some reason they've
recently received antibiotics.
Fourthly, Staph aureus - that's the big bug
and that's why you'll need Vancomycin on board
You can see strep, you may see
gram negatives but look for Staph
and because of that, Vancomycin
is your starting antibiotic
or you can narrow to Ceftriaxone or something
down the road once you got to more data.
You may need to irrigate the joint
depending upon which joint is involved.