[Music] 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 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 scarletina form 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 pasty 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. 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 grey 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. They can be on the buccal mucosa and 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 streptococcus can also cause pharyngitis, Group C and G. But I want to spend a moment on fusobacterium.

McCraw, from which is an unusual cause of pharyngitis, and seems to occur most commonly in young adults. 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 a syndrome called Lemierre's syndrome, which is characterized by suppurative jugular venous thrombosis. 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 and Akram and Lemierre's syndrome. This is an

organism that reportedly produces syndrome very much like group A strep pharyngitis called arc que no bacterium hemolytic them. 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 scarlet inna form rash, so it can mimic. And I'm waiting more about corynebacterium diphtheria on Gram stain. These organisms are grande positive bacilli, and they tend to 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 diff theory, 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 include the airway. It can get into the larynx.

and is it cause of asphyxiation in a 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 gonorrhea by taking a careful sexual history. That generally 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. A usually produce kind of a viral-like syndrome, and they will often have headache, cough, fatigue. So remember, if they've got cough, it's not very likely group A strep infection, and they will have sore throat.

and from 30 to 70%, and particularly with chlamydophila, the incubation period is actually long, and 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 a 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 an exam, you find mild to moderate tonsillar enlargement with exudates. So the exudates can look an awful lot like 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 may 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 a 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 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. So, turning now to how do you actually diagnose group A streptococcus pharyngitis. Well, since the 1960s, physicians in primary care have been employing the Centor criteria, and they have been modified as follows. It's actually a scoring system to help a physician determine whether to get a throat culture and whether to use antibiotics. So, if the patient is from 3 to 14 years of age, then as you can remember, group A strep is likely, so they get 1 point for that. If they're 15 to 44, it's sort of come cecum saw. They don't really get a point. If they're over 45.

years of age, then of course, group A strep becomes less and less common. And you take away a point, they get a minus 1. If on exam you find the eggs, you date or swollen tonsils, you give them a point. If they have tender swollen anterior cervical nodes, they get another point. If they have fever more than 38, they get another point. And remember this, if they do not have a cough, they get a point. But if they have a cough present, they get nothing. So how do you use this scoring system? If their added up score is minus one or one, their risk of group A strep is less than 10%, so they should get no antibiotic and no throat culture. We could save a lot of money and save a lot of allergic reactions if we would follow that. If they have a score of two or three, their risk of strep is between fifteen and thirty-two percent, still pretty low but possible, so you would get a throat culture and but you wouldn't

give antibiotics until you found the results of the throat culture, and if it's group A strep, you then treat them. You still have some time; you really have up to ten days to prevent the sequela of group A strep, so you can wait for the culture. If they have a score of four or five, their risk of group A strep, it's not a hundred percent by any means, it's only fifty-six percent. You would certainly then go ahead and either do one of the rapid strep screens or culture and give antibiotics if positive. And I want to emphasize the current recommendations of the Infectious Disease Society of America: empiric treatment is no longer recommended just on the basis of symptoms alone. And the other thing about antibiotics, let's say a patient has had three days of a sore throat, and it's caused by group A strep. If you give antibiotics after three or four days, the antibiotics don't do anything for the symptoms, so you're not going to hasten the resolution of the symptoms. Yes, you will eradicate strep.

the throat, but you have to really get any resolution of symptoms. You've got to start antibiotics within the first 24 hours, ideally. So, there's no rush. If the patient's had several days of symptoms, you can wait to get the culture, and you can wait up to 10 days to prevent the sequela. A throat culture is very sensitive and very specific for a group A strep. The microbiologists deal with this organism all the time, and they can recognize it quickly. There are rapid antigen detecting systems. They have a decent sensitivity from 70 to 90 percent, not as good as culture, but their specificity is about the same as a culture. And here, you're showing group A strep growing on blood agar, and there's a zone of inhibition around a bacitracin disc in most cultures, not particularly shown in this one, but you can see the beta hemolysis. So, the goals of treatment then for group A streptococcal infection, and really that's the main one we're focusing on, is the resolution of

symptoms, and you need to start early. As I mentioned, this also is a contagious disease, so the earlier you start, the less contagious the patient will be. And if you can start within ten days, you can reduce the risk of complications. So, what is the treatment? Well, it's my favorite antibiotic, penicillin, and in the form of oral penicillin, it would be penicillin V or amoxicillin. And we generally use a 10-day course because that's generally required to get rid of strep from the pharynx. Remember, amoxicillin given to somebody with infectious mononucleosis can cause a rash. If a patient has a penicillin allergy, then we prescribe azithromycin, clarithromycin, or clindamycin. And there are intramuscular regimens in patients that really can't take oral medication for some reason. You can give them a dose of long-acting benzathine penicillin G, dosing according to their kilogram weight, if they do have that.

dreaded anaerobic infection views of bacterium the craw from. We've got to use something that is very good for anaerobes, and we will probably hospitalize these patients because many of them are sick. It's recommended that they get ampicillin, sold back Tam. Now, the so back Tam is a beta-lactamase inhibitor. It's what you call a suicide beta-lactamase inhibitor. It will remove all of the beta-lactamase produced by this organism out of the system so that ampicillin, which it's attached to, can go do its thing on the bug. Many people recommend that you add metronidazole for extra anaerobic coverage because it tends to penetrate clots. I'm not certain whether you absolutely need to use metronidazole, but that's what's recommended for corynebacterium diphtheria. You can remove the organism in somebody with active diphtheria with penicillin, but to actually get rid of somebody who simply colonized penicillin.

won't work. A macrolide is needed. So, we talked about the complications that we're trying to prevent, and these are they: a peritonsillar abscess doesn't have to be caused only by fusobacterium, but can be caused by group A strep. You can get these dreaded parapharyngeal space infections, which can involve the dangerous areas of the head and neck. Lymphadenitis, sinusitis, and otitis media can result, and mastoiditis in very serious complicated otitis. Necrotizing fasciitis is pretty rare, and so in this case, we would be talking about necrotizing fasciitis of the soft tissues of the neck. Group A strep can produce the toxic shock syndrome, which is characterized by diffuse erythema of the skin with desquamation, hypotension, and it can result in multi-organ failure. And this is caused by a cytokine storm, which the organism can result in liberating from phagocytic cells. There are some non

separative complications, as well the most dreaded, of course, is acute rheumatic fever and rheumatic heart disease. Back in the days before antibiotics were available, this was a very common problem because group A strep was common. We couldn't treat that; there were no antibiotics. So, we looked at a lot of the complications. Another complication, which is fortunately not so common, is that of acute glomerulonephritis. Here, I'm showing on the left-hand picture what a normal glomerulus looks like, a tuft of glomerular capillaries. I think you can see how busy the glomerulus is in acute glomerulonephritis and how cellular it is. What you're really looking at is neutrophils that have responded to it, antibodies that are located in the glomerulus, and they're causing essentially destruction of that glomerulus. This brings me to the end of my discussion about pharyngitis. I hope that it's been helpful to you. [Music]

Group A Streptococcus (GAS) – Infectious Diseases | Lecturio

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