The microbiology of sinusitis actually
reflects the upper respiratory tract flora.
So you shouldn’t be surprised
that Streptococcus pneumoniae
is the most common cause
of bacterial sinusitis
followed close behind by
Anaerobes are not a real
common cause of sinusitis
unless the patient has chronic
blockage of the ostia.
That’s when anaerobes
can survive there.
Streptococcus species don’t cause
acute sinusitis very often.
Moraxella catarrhalis has a
low incidence in adults,
but a much higher incidence in children.
And the miscellaneous pathogens and
staph aureus account for the rest.
So acute sinusitis is common,
but it’s most commonly
caused by viruses.
And I just want to point out that children
and those adults who have small
children know this very well.
Children get the common cold
five to seven times each year,
and so do their parents.
Now, adults who don’t have small children
will get two to three colds a year.
You probably can document
that on your own experience.
I want to point out, however, how uncommon
complicating bacterial sinusitis is.
Only 6% to 13% of kids
get bacterial sinusitis
even though they get five to
seven common colds a year.
So that’s pretty unusual.
And adults get bacterial sinusitis
from 0.2% to 2.5% of the time.
So, most of the time when an adult
comes into the office complaining
of nasal congestion and having
purulent nasal secretions,
they still have the common cold,
they don’t have bacterial sinusitis,
and it’s over-diagnosed and it certainly
is over-treated with antibiotics.
So, in a viral upper
respiratory tract infection,
it starts out, as everybody
knows, clear and watery.
And it then becomes thick and mucoid
and even in viral sinusitis,
viral common colds,
it becomes greenish
All that means is that neutrophils
have come in to the secretions
and made the color
yellow or green.
Low-grade fever is not common in adults,
but it is fairly
common in children.
And the common cold,
and we should all advise
our patients of this,
the common cold lasts
normally five to ten days.
So, the patients are
likely to come in to the
doctor in the second week
of the illness saying,
“I’m not well. I’ve got bacterial
sinusitis, doc. I want some antibiotics.”
But they still have the
residual of a common cold,
most of them, not
We start thinking about bacterial sinusitis
if they’ve had more than ten
days of nasal discharge,
if they have low-grade fever,
if they have malodorous
breath which reflects
the possibility of
and we certainly worry about it
if they have periorbital edema
because that usually means
a bacterial sinusitis.
Viruses don’t do that.
We also think about it if their symptoms
were getting better from their common cold,
but now they’re starting to have
increased discharge and congestion.
So, they were starting to ease off,
and then they turn around and
start going the other way,
or if they develop new fever,
or if they start developing
a cough in the daytime.
So one of the things that is most
important to an evaluating physician is
how long the respiratory
symptoms have been there.
That’s the most useful factor for
diagnosing bacterial infection.
Symptoms or signs lasting more than ten days
without clinical improvement of any kind,
that’s when we think about
certainly, if they have purulent nasal discharge
and high fever for three to four days
because high fever isn’t
common in viral sinusitis.
Or let’s say they have new fever, headache,
or increased discharge after five to
six days of a typical viral syndrome.
And by the way, the headache is generally
located anteriorly where the sinuses are
and particularly aggravated
by leaning forward.
Those are indications of a
possible bacterial sinusitis.
So if a patient has what
we call “double sickening”
we would begin to think about
What about imaging in acute sinusitis?
This is overused, as well.
you don’t need to
image the sinuses.
If you are to image somebody
with the common cold,
and it’s done far
you would find sinus thickening, you might
even find air fluid levels in the sinuses
of somebody who has nothing
more than the common cold.
The imaging generally can’t confirm
a diagnosis of bacterial sinusitis.
Just one aside is that if
somebody had fungal sinusitis,
you may show invasion
of the bones.
That would be a serious problem.
But generally, imaging is not
indicated in acute sinusitis.