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Community Acquired Pneumonia (CAP) – Exam Practice Question

October 13, 2019

welcome to another MedCram board
vitals question this question comes from our family nurse practitioner banks and
the question is what are the three bacterial organisms that are the most
common causes of agents of CAP or community acquired pneumonia in adults
first choice is a and that’s Klebsiella pneumoniae Pseudomonas aeruginosa and
Hamas influenza B is mycoplasma pneumoniae chlamydia pneumonia and
streptococcal pneumonia which is the correct answer C is Hamas influenza
chlamydia pneumonia and Moraxella catarrhalis and D is Legionella species
chlamydia pneumonia and mycoplasma pneumoniae so which one is the right
answer in this case it’s B but the question is is why is it the right
answer so let’s review that so I wanted to go over these eight different
bacteria and their characteristics so the first thing you should know is that
streptococcal pneumonia is actually the most common bacterial cause for
pneumonia so right off the bat that is the biggest thing you should know you
should know that streptococcal pneumonia is the most common bacterial cause for
pneumonia and if you’ll remember on a Gram stain they’re going to look like
gram positive cocci in pairs so that’s the thing to look for is you’ll see
those in pairs like that now the next one is Hamas influenza
homophonous influenza is also seen in community acquired pneumonia very
commonly but not as commonly a strep pneumo it’s also seen in COPD so make
sure you’re aware of that as well Klebsiella pneumoniae not as commonly
seen in pneumonia it’s not a common cause of it but it is associated with
alcohol consumption these two right here chlamydia pneumonia and mycoplasma
pneumoniae are bacteria that do cause pneumonia but they cause a different
clinical syndrome whereas that these ones that we’ve
talked about here cause a typical type of pneumonia
these are very commonly called an atypical now be aware that atypical
pneumonia and typical pneumonia are still under the umbrella of community
acquired pneumonia which is what the question was dealing with so there is
typical and there’s a typical so be aware of that and a typical clearly are
these two right here they are also very commonly seen in cap even though they
are a typical atypical means that they’re gonna have this type of walking
pneumonia it doesn’t present typically typical pneumonia is fever white count
infiltrate feeling short of breath things of that nature now for the next
one I’m gonna use the color green because Pseudomonas is classically green
in color so if you see a patient with green sputum it doesn’t necessarily mean
they have Pseudomonas aeruginosa but you may want to think about it especially if
they’ve got lung disease chronic lung disease like COPD bronchiectasis
especially cystic fibrosis this is classic cystic fibrosis now the reason
why you should know about Pseudomonas aeruginosa even though it’s not one of
those bacteria that’s commonly found in cap is because of antibiotic resistance
and we’ll just touch on that briefly but first I want you to remember that
Pseudomonas aeruginosa is typically not seen in community acquired pneumonia
because these are seen in more hospital-acquired or healthcare acquired
pneumonia so it’s not one of the most common ones for cap so what do we
typically treat suna mones originally with well there’s a number of different
of antibiotics for Pseudomonas aeruginosa but you can think about the
fluoroquinolones you can think about the carbapenems you can think about the
amino glycosides all of those cover them there are some third and fourth and
fifth actually generation cephalosporins that cover it like ceftazidime cefepime
and azure boxa which is a more recent generation cephalosporin and then you
can get into some of the other ones for instance aztreonam which is a mono
lactam which can cover Pseudomonas there’s the carbon atoms as we talked
about like meropenem there are the fluoroquinolones as we mentioned those
are the only ones that are available orally the key though here is
Pseudomonas aeruginosa is a very specific bacteria that you’ve got to
know a lot about not typically seen in cap Moraxella catarrhalis kind of known
as MCAT for those of you who have to take the MCAT MCAT or Alice is typically
seen in acute otitis media it can also be seen in COPD as well and then finally
the last one here is Legionella Legionella we would not consider part of
cap because it’s typically seen in outbreaks so think of this in outbreaks
if there’s an epidemic okay that would be on a cruise ship or air conditioning
or in a hotel that’s what you want to think about Legionella not in cap so
what are ones that we see in cap we see streptococcal pneumonia in cap we see
Hamas influenza in cap we see these atypicals in cap cap stands for
community acquired pneumonia this is chlamydia pneumonia and this is
mycoplasma pneumoniae so we’re back with the question now and the question again
is which are the three bacterial organisms that are the most common
causes of agents of CAP well if you just go with the very first thing that we
said which was that streptococcal pneumonia is the most common the only
one of these answer choices that has streptococcal pneumonia in it is correct
chlamydia pneumonia and mycoplasma pneumoniae are the other two and
therefore B is the correct answer Klebsiella pneumoniae is seen in
patients who drink a lot of alcohol not necessarily cap we talked about that
Pseudomonas aeruginosa is not seen in cap and hemolysis influenza is seen in
cap by the way influenza here this is not the flu virus this is a bacteria
just so you’re aware see Hamas influenza yes chlamydia pneumonia yes
and catalyst no that is not seen typically in or commonly in
community-acquired pneumonia for D Legionella species we’ve already said
that this is not part of the community acquired pneumonia
Kadri of bacteria this is seen in outbreaks this is seen spread by water
air conditioners things of that nature the other two though are part of cap and
that’s Klebsiella pneumoniae and mycoplasma pneumoniae thanks for joining


  • Reply MedCram - Medical Lectures Explained CLEARLY April 15, 2017 at 6:00 pm

    See more Board Questions like this and the complete library of MedCram videos at

  • Reply غرائب | و حقائق April 16, 2017 at 2:43 am

    Thanks from Saudi Arabia

  • Reply Idel Fernandez April 21, 2017 at 5:32 pm

    Dr. Thank you for your videos. I would like to ask if it is possible to upload a video regarding Calcium metabolism and diseases. Thank you again for the amazing job and effort put on teaching.

  • Reply vab bbb May 30, 2017 at 11:04 am

    epic video keep it up sir

  • Reply pranay hedaoo June 3, 2019 at 9:32 pm


  • Reply Derek Linskey June 19, 2019 at 11:20 pm

    You should have mentioned Zosyn for P. aeruginosa as you mentioned it is more frequently a cause of HCAP

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