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Group A Streptococcus (GAS): Symptoms & Other Clinical Features – Infectious Diseases | Lecturio

October 21, 2019

So let’s get back to the symptoms
and other clinical features of group A streptococcal
pharyngitis. Number one, and it’s usually a pretty
bad sore throat, is painful swallowing. And in addition to that, the
patients will very often have fever, not extremely high-grade,
but at least 38.5 or more, and they may even have some GI symptoms, which can deter the physician
from making a specific diagnosis. They will have nausea,
vomiting, and abdominal pain, which is sometimes confusing to the
physician evaluating the patient. Most patients have a bright red posterior
pharynx with tonsillar enlargement and they have often have
exudative tonsillitis, meaning a gray-white exudate
covering one or both tonsils. And a clue that’s often
missed is edema of the uvula, which you may be able to detect
in this particular view. Another finding is that of
petechiae on the soft palate. In addition, many patients have painful
anterior cervical lymphadenopathy. Of utmost importance is
the absence of a cough. So if you have a patient
that’s got sore throat, cough, hoarseness, nasal congestion, that’s probably not
group A strep. That’s probably a viral pharyngitis,
bronchitis, laryngitis, it’s viral. So the absence of a cough
is an important point in the evaluation of someone
with a sore throat. Some patients, if they have a
particular strain of group A strep that produces this toxin, they may have a scarlatiniform rash,
the so-called rash of scarlet fever. This begins on the trunk and generally
tends to spare the extremities. And if you look at the creases in the
elbows, they may be slightly darkened. These are referred to as Pastia’s lines. And this rash has a sandpaper-like quality because the sweat glands
are slightly edematous and you can feel the skin having
sort of a rough texture to it. Some other conditions that one needs
to consider in the evaluation are certainly herpangina, which is caused
by Coxsackie A virus most commonly. And you may be able
to note the vesicles and ulcers on the soft palate. And one thing about herpangina is
most of the lesions tend to be posteriorly located in the pharynx. We certainly wouldn’t
want to miss diphtheria, these patients have an
adherent gray membrane, and then infectious
mononucleosis. They also may have palatal
petechiae like group A strep. The difference would be this
is more of a subacute illness than an acute illness like group A strep. And then we can’t forget oral candidiasis
and you should note the white plaques that you find and they can be in the
buccal mucosa, on the posterior pharynx, they can be on the tongue. And the pearl is, if you have a
patient coming in with pharyngitis with oral candidiasis,
they need an HIV test. Other streptococci can also cause
pharyngitis, group C and G. But I want to spend a moment
on Fusobacterium necrophorum, which is an unusual cause of pharyngitis and seems to occur most
commonly in young adults, and the pharyngitis may
be indistinguishable, at least the way it looks, from
group A strep pharyngitis. But what I wanted to focus
on are the complications. This organism is an anaerobe and it can cause blood to clot in veins, so it can cause a peritonsillar abscess. And what we fear most about this organism
is the syndrome called Lemierre’s syndrome, which is characterized by suppurative
jugular venous thrombophlebitis. So the jugular vein is
closed off by a clot and, furthermore, it’s an infected clot, and so as an infected clot, it can
disseminate organisms all over the place. For example, these patients may
have abscesses in their lungs, they may have positive blood
cultures, they may be deathly ill. So we can’t overlook the possibility of Fusobacterium necrophorum
and Lemierre’s syndrome. This is an organism that reportedly produces a syndrome very
much like group A strep pharyngitis called
Arcanobacterium haemolyticum. It must be very rare. I think you can see that I’ve probably
seen many patients in my years, but I have yet to
recognize this. But you need to know that it can
produce a scarlatiniform rash, so it can mimic,
and I’m waiting. More about Corynebacterium diphtheriae. On Gram stain, these organisms
are Gram-positive bacilli and they tend to clump together, some
people say, like Chinese lettering, and we don’t find this in developed
countries because people are immunized. But in a developing country, a patient
may come in with this diphtheriae and they may present with a
sore throat, low-grade fever, and they will have this adherent, gray
membrane that’s difficult to remove. And by the way, this membrane can
be located not only on the tonsils, but this can actually occlude the
airway, it can get into the larynx, and is a cause of asphyxiation
in minority of patients. So we need to be able
to make this diagnosis and protect the
airway if necessary. The other thing these patients have is
very impressive cervical lymphadenopathy. The lymphadenopathy is so impressive
that it may give the patient, as in this young girl, a
bull neck type appearance. And of course we can’t forget to at
least consider Neisseria gonorrhoeae by taking a careful sexual history. Generally, it does not cause
a very severe sore throat. In fact, you can actually be colonized by
Neisseria gonorrhoeae without any symptoms. So paramount is taking
a good sexual history, and there are the organisms on Gram
stain, Gram-negative diplococci. Mycoplasma pneumoniae and
Chlamydophila pneumoniae usually produce kind of
a viral-like syndrome and they will often have
headache, cough, fatigues, or remember, if they’ve got cough, it’s
not very likely group A strep infection. And they will have sore
throat in from 30% to 70%. And particularly with Chlamydophila, the incubation period
is actually quite long, maybe two or three weeks since
they were exposed to someone who had something similar. Now, for infectious mono,
we need to spend some time on this disease because
it’s fairly common. But I want to emphasize that
this is a subacute illness. These patients have been
complaining of the sore throat and fatigue for maybe
two or three weeks Finally, they come to the doctor. One interesting point is that when they first
went to the doctor with their sore throat, they may have been
given amoxicillin and developed a rash and so they were told they were
probably allergic to amoxicillin. On exam, you find mild to moderate
tonsillar enlargement with exudates. So the exudates can
look an awful lot like a group A strep and they also may
have those palatal petechiae. They will have very
impressive lymphadenopathy, and it’s not only anterior cervical, but
it’s posterior cervical lymphadenopathy, and in my experience, axillary
lymphadenopathy is common and splenomegaly. And as a matter of fact, if you suspect infectious mono in a patient, you should carefully examine the
abdomen for a palpable spleen. And if this is a young athlete, then you need to advise them that they need to stay away from contact
sports if they have splenomegaly, because if they have splenomegaly and
they get trauma to their left side, then they can actually rupture
their spleen and bleed out. So a physician needs to really
carefully evaluate somebody with mono for splenomegaly. And regardless of what you do, they will
gradually get better over about a month. But this is kind of a nagging
illness for teenagers. It is spread by intimate kissing, and as you can imagine, that’s
pretty common in teenagers so we need to have our antenna up
for this cause of sore throat. And then once again, remember
that — and this is curious — that if they get antibiotics,
particularly amoxicillin, a large percentage of them
will break out with a rash and then the amoxicillin will
forever be listed as an allergy. But it’s not related to an
allergy to amoxicillin, it’s just something related
to infectious mononucleosis which we don’t clearly understand. It’s an idiosyncrasy of that illness.


  • Reply MisterBassBoost May 29, 2017 at 11:07 am

    Fantastic video! Keep it up!

  • Reply Rosé Emad May 30, 2017 at 11:45 pm

    is this course free and the causes which you are send to me on my email… please answer I'm in trouble ?? are you need many for this courses or no

  • Reply Tal Mor April 21, 2018 at 9:02 am

    amazing thank you

  • Reply scifiaudious2 May 6, 2018 at 7:09 am

    great presentation

  • Reply pink flower January 1, 2019 at 11:47 pm


  • Reply Cari May 14, 2019 at 1:08 am

    why medical students do not need microbiology for the admission to medical school?

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