Acute group A streptococcal infections and sequelae (pediatrics): Clinical sciences

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Introduction0:00–0:40

Streptococcus pyogenes, also called group A Strep or GAS for short, is a toxin-producing bacterium that can cause various upper respiratory, skin, and soft tissue infections, as well as associated sequelae.
These include life-threatening conditions like streptococcal toxic shock syndrome, or STSS; as well as less severe conditions, like impetigo, erysipelas, cellulitis, pharyngitis, or scarlet fever.
GAS is also known to cause clinical sequelae such as poststreptococcal glomerulonephritis and acute rheumatic fever.Now, if your patient presents with a chief concern suggesting a GAS infection or its sequela, first perform an ABCDE assessment to determine if they are unstable or stable.

Unstable Patient0:40–2:20

If unstable, stabilize their airway, breathing, and circulation; obtain IV access, and consider starting IV fluids. Next, put your patient on continuous vital sign monitoring, including heart rate, blood pressure, and pulse oximetry, and if needed, provide supplemental oxygen!
Finally, if your patient’s condition permits, don’t forget to obtain a blood culture, as well as a wound culture if a wound is present.
Then, start broad-spectrum intravenous antibiotics right away! Now, here’s a high yield fact!
Patients with GAS infections may present as unstable for a number of reasons. One you should especially consider is toxic shock syndrome due to GAS.
This is often associated with some sort of strep infection, such as cellulitis or a recent strep pharyngitis, as well as vital sign instability, skin desquamation, and possibly necrosis.
If you suspect toxic shock syndrome, provide supportive care, consult surgery to debride any necrotic tissue, and treat with antibiotics that have activity against GAS.
These antibiotics should include clindamycin or linezolid because they have an antitoxin effect. Also keep in mind that some patients are so sick that you may even consider additional treatment with intravenous immunoglobulins.Okay, now let’s go back to the ABCDE assessment and take a look at stable patients.

Stable Patient2:20–2:30

Your first step is to obtain a focused history and physical exam. First, let’s discuss patients with nonbullous impetigo.

Impetigo2:30–3:06

In this case, your patient will report a rash, usually around the nose or mouth, described as being “stuck on” the skin.
Physical exam findings typically include a facial rash consisting of papulovesicular lesions with localized erythema, as well as purulent vesicles with a honey-colored crust.
These findings are highly suggestive of nonbullous impetigo. You can treat localized impetigo with topical mupirocin; however, if skin lesions are widespread, proceed with oral cephalexin!
Okay, now, let’s take a look at patients with erysipelas or cellulitis. These individuals typically report a bright red rash, most commonly on the extremities or face, and sometimes the perianal skin or vaginal mucosa.

Erysipelas/Cellulitis3:06–4:11

The physical exam will usually reveal elevated temperature; swelling, erythema, and tenderness of the affected area; and a sharply defined rash with a slightly elevated border.
In some patients, you might notice ascending lymphangitis, which appears as redness streaking to adjacent lymph nodes within the groin or axilla.
At this point, you can diagnose either erysipelas or cellulitis, which are two similar yet distinct conditions. While erysipelas involve the superficial layers of the skin and have a sharper demarcation, cellulitis affects the deeper skin layers, it is less defined, and it has a reddish-to-purple color.
Treatment for both erysipelas and cellulitis includes oral penicillin or amoxicillin.Alright, let’s switch gears and move on to streptococcal pharyngitis.

Streptococcal Pharyngitis/Scarlet Fever4:11–5:25

Affected individuals report a history of fever, sore throat, and absence of cough. Some patients also report abdominal pain, vomiting, or known sick contacts.
Physical exam findings typically include tonsillar exudates, soft palate petechiae, erythema or swelling of the uvula, as well as anterior cervical lymphadenopathy.
These findings should make you suspect streptococcal pharyngitis.On the flip side, individuals with scarlet fever have symptoms of streptococcal pharyngitis, like fever, sore throat, and absence of a cough.
They also have a rash that erupts one to three days after these symptoms appear. On physical exam, you will detect a blanching, papular scarlatiniform rash with a sandpaper texture.
Other important findings include a “strawberry tongue,” as well as Pastia lines, which are accentuated red lines visible in flexor creases, such as the antecubital fossa or the groin.
At this point, you should suspect scarlet fever.Now, whether you suspect streptococcal pharyngitis or scarlet fever, your next step is to order a rapid streptococcal antigen test.

Diagnosis5:25–6:43

If the test is positive, you can diagnose streptococcal pharyngitis, with or without scarlet fever, but if the antigen test is negative, your next step is to order a throat culture.
If the throat culture grows GAS, again, you can diagnose streptococcal pharyngitis, with or without scarlet fever.Now, the treatment of streptococcal pharyngitis and scarlet fever primarily relies on oral or intramuscular penicillin.
Alternatively, if your patient is penicillin-allergic, you should go with cephalexin, clindamycin, or azithromycin. If your patient has scarlet fever, provide supportive care for the rash.
Now, here’s a high yield fact to keep in mind! Treating an acute strep infection, like impetigo, erysipelas, cellulitis, strep pharyngitis, and scarlet fever, can prevent acute rheumatic fever, a known sequela of untreated GAS infection.
However, keep in mind that antibiotics do not prevent post-streptococcal glomerulonephritis, which is another important sequela of GAS infection, but it does prevent the spread of nephritogenic strains to other people.
Speaking of sequelae, let’s move on to post-streptococcal glomerulonephritis! Affected individuals typically report frankly bloody, cola- or tea-colored urine, swelling of extremities, and joint pain.

Post-Streptococcal Glomerulonephritis6:43–8:20

Additionally, your patient will report a recent strep infection, like pharyngitis seven to ten days prior, or a skin infection two to four weeks prior.
Next, the physical exam usually reveals elevated blood pressure and periorbital or pedal edema. At this point, you should suspect poststreptococcal glomerulonephritis, so your next step is to order labs, including serum creatinine, complements C3 and C4, antistreptolysin-O titer, and urinalysis with microscopy.
Labs will likely reveal an elevated creatinine, low C3, normal C4, and an elevated antistreptolysin-O titer. Additionally, the urinalysis will demonstrate hematuria with or without proteinuria; while the urine microscopy will reveal the presence of red blood cells and red blood cell casts.With these findings, you can diagnose poststreptococcal glomerulonephritis and proceed with treatment, which mainly relies on supportive care and includes sodium and water restriction, as well as loop diuretics.
Finally, if your patient with poststreptococcal glomerulonephritis has an ongoing acute GAS infection, be sure to also treat the active infection with antibiotics!
Now, let’s switch gears and discuss acute rheumatic fever. Affected individuals typically report having a recent infection associated with sore throat, with or without tonsillar exudates; and they might report fever and joint pain.

Acute Rheumatic Fever8:20–10:12

Important physical exam findings you should pay attention to include a heart murmur; joint tenderness, occasionally with an effusion; a serpiginous rash; painless subcutaneous nodules on the shin; or abnormal, involuntary movements.With these findings, you should suspect acute rheumatic fever, so your next step is to order labs.
These include a rapid strep antigen test and throat culture; strep antibody testing, like antistreptolysin-O and anti-DNase B titers; and inflammatory markers, such as ESR and CRP.
You should also order a 12-lead ECG and an echocardiogram. Labs typically reveal a positive rapid strep antigen or throat culture; as well as elevated strep antibodies and inflammatory markers.
ECG might reveal a prolonged PR interval, while the echo might demonstrate valvulitis.Your next step is to compile all these findings to assess for the Jones criteria.
These include the presence of arthritis, valvulitis, subcutaneous nodules, erythema marginatum, or Sydenham chorea. If Jones criteria are met, you can diagnose acute rheumatic fever.
Treatment includes oral or intramuscular penicillin, with or without anti-inflammatory medications like NSAIDs, salicylates, or corticosteroids.
Finally, treatment should include long-term antibiotic prophylaxis.Alright, as a quick recap… Streptococcus pyogenes, also called group A Strep or GAS for short, is a toxin-producing bacterium that can cause various upper respiratory-, skin- and soft tissue infections and associated sequelae.

Review10:12–10:59

If your patient presents with a chief concern suggesting GAS infection or GAS sequela, first perform the ABCDE assessment to determine whether they are stable or unstable.
If stable, consider active GAS infections, such as impetigo, erysipelas, cellulitis, pharyngitis, and scarlet fever. Additionally, you should always keep in mind GAS sequelae, like poststreptococcal glomerulonephritis and acute rheumatic fever.
Acute group A streptococcal infections and sequelae (pediatrics) | Osmosis