Staphylococcal scalded skin syndrome and impetigo: Clinical sciences

Chapters:

Watch video only

Introduction 0:00–0:38

Staphylococcal scalded skin syndrome and impetigo are common pediatric skin infections that are most often caused by Staphylococcus aureus.
While impetigo usually results from direct bacterial invasion of the skin or minor skin trauma, staphylococcal scalded skin syndrome is caused by hematogenous spread of Staphylococcal exotoxins from colonized areas to distal sites.
Exam findings can be used to distinguish mild Staph infections such as impetigo from more severe infections like staphylococcal scalded skin syndrome.
Now, if a pediatric patient presents with a chief concern suggesting staphylococcal scalded skin syndrome or impetigo, first perform an ABCDE assessment to determine if they are stable or unstable.

Unstable Patient 0:38–1:14

If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access and administer IV fluids.
Put your patient on continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry. If needed, provide supplemental oxygen.
Also remember to start antibiotics if you suspect your patient is septic! Now that we’ve discussed unstable patients, let’s go back to the ABCDE assessment and look at stable ones.

Stable Patient 1:14–1:55

First, obtain a focused history and physical examination. The history will reveal a rash, possibly in combination with fever.
As far as the exam goes, you’ll notice skin lesions that appear as vesicular or bullous. At this point, you should distinguish impetigo from staphylococcal scalded skin syndrome by assessing the presence of a Nikolsky sign, meaning that applying lateral pressure to the bullae or vesicle causes the upper skin layer to pull away from the underlying layers to reveal a raw, red base.
If the Nikolsky sign is negative, suspect impetigo. This is a common, superficial bacterial infection that’s highly contagious.

Impetigo 1:55–7:42

Impetigo can be either nonbullous or bullous, and history and exam findings can differentiate the two. Let’s start with nonbullous impetigo.
The history usually reveals an infant or young child with a mildly pruritic rash. Affected patients often acquire the infection during the summer months or reside in a warm, humid climate.
Examination of the rash reveals vesicles on an erythematous base most commonly around the nares, perioral region, or extremities.
The lesions rupture and form honey-colored crusts. Some patients may also demonstrate regional lymphadenopathy.
These findings should make you suspect nonbullous impetigo, which you can usually diagnose on the basis of clinical findings.
However, if the diagnosis is unclear, consider obtaining a Gram stain and culture of the skin lesions. If the Gram stain reveals gram-positive cocci in clusters, and the culture grows Staphylococcus aureus, diagnose nonbullous impetigo.
Now here’s a clinical pearl to keep in mind! While both Staph.
aureus and group A beta-hemolytic Streptococcus can cause nonbullous impetigo, the majority of cases are caused by Staph.
aureus. Once you’ve diagnosed nonbullous impetigo, your next step is to assess for signs indicating extensive disease.
In particular, look for more than 5 lesions; any deep tissue involvement; and systemic signs of infection, such as fever and lymphadenopathy.
If these signs are absent, diagnose localized nonbullous impetigo. Treatment involves carefully removing crusts with soap and warm water, and applying topical mupirocin to the rash.
Because impetigo is extremely contagious and spreads quickly in daycare and school settings, your patient should avoid contact with others until they have completed 24 hours of antibiotics.
Also advise patients and caregivers to wash their hands, linens, and clothing regularly, and to avoid sharing personal items like towels.
It may also be helpful to cover your patient’s lesions with a non-stick bandage to help prevent spreading the infection.
Additionally, if your patient has a history of recurrent impetigo, consider topical mupirocin for decolonization of the nares.
Now, if any signs indicating extensive disease are present, diagnose disseminated nonbullous impetigo. Treatment involves oral antibiotics that have activity against gram-positive organisms, such as first-generation cephalosporins, or antibiotics that contain a beta-lactamase inhibitor, such as amoxicillin-clavulanate or dicloxacillin.
If there is a high local prevalence of methicillin-resistant Staphylococcus aureus, or MRSA; consider prescribing doxycycline or clindamycin instead; and if you ordered cultures, tailor antibiotics based on sensitivities.
Keep in mind, doxycycline is safe for young children in a short course. Also, tell your patient to avoid sun exposure as doxycycline can cause phototoxicity, so they are much more likely to get sunburned.
Just as with localized impetigo, these patients should avoid contact with others until they’ve completed 24 hours of antibiotics.
Also provide counseling on hand washing; washing of linens and clothing; and avoiding sharing personal items. Finally, consider covering lesions with nonstick bandage to prevent transmission, and apply topical mupirocin to the nares if you suspect colonization with Staph.
Now, let’s switch gears and discuss bullous impetigo. These patients are typically neonates or infants with a rash, and may also present with fever, weakness or diarrhea.
Examination reveals a rash composed of vesicles that have enlarged and evolved into flaccid bullae filled with clear, yellow fluid that often turns cloudy.
The lesions are commonly located in the intertriginous areas, like the diaper area, but can also form on the face, trunk, or extremities.
Upon rupture, the lesions leave behind a thin, brown crust and a narrow collarette, or rim, of scale at the edges of the ruptured lesion.
The presence of these findings suggests bullous impetigo, which is usually a clinical diagnosis. However, if needed, you can obtain a Gram stain and culture of the skin lesions.
If the Gram stain reveals gram-positive cocci in clusters, and the culture grows Staphylococcus aureus, diagnose bullous impetigo.
While nonbullous impetigo can be caused by either Staph or Strep, bullous impetigo is nearly always caused by exfoliative toxins produced by Staph.
aureus. Just as with generalized nonbullous impetigo, you should treat bullous impetigo with oral antibiotics, such as first generation cephalosporins, or beta-lactamase-resistant antibiotics, like amoxicillin-clavulanate or dicloxacillin.
If you’ve confirmed a Staph. aureus infection, you might consider prescribing trimethoprim-sulfamethoxazole, since this antibiotic is effective against Staph, but lacks activity against Streptococcus.
Also, advise your patient to avoid contact with others during the first 24 hours of treatment, and to wash their hands, linens, and clothing regularly.
Finally, consider covering the lesions, and apply mupirocin to the nares if you suspect your patient is colonized with Staph.
Now, let’s switch gears and discuss patients who have a positive Nikolsky sign. This finding should make you suspect staphylococcal scalded skin syndrome, or SSSS.

Staph Scalded Skin Syndrome 7:42–10:48

This severe skin infection is associated with extensive skin exfoliation caused by Staphylococcal exfoliative toxins. Here’s a clinical pearl!
In SSSS, exfoliative toxins, called epidermolytic toxins A and B, target desmoglein 1, a protein that promotes adhesion and structure in the epidermis.
This causes the stratum granulosum to separate leaving behind moist, red, tender skin resembling a burn or scalded skin, which explains the name!
Patients with SSSS are usually neonates, infants, or young children, though it can occur in older children and adults. Patients typically present with a sudden onset of symptoms like irritability, fatigue, and poor feeding.
Physical examination may demonstrate fever and conjunctivitis, as well as tender, generalized erythroderma that evolves into diffuse, flaccid, bullae.
The bullae rupture, leaving behind areas of moist, erythematous, denuded skin. Also, you’ll often see perioral and perinasal crusting and desquamation, with sparing of the mucosa.
These findings are highly suggestive of SSSS. You can usually diagnose this clinically, but to confirm the diagnosis, consider ordering a skin biopsy or a Gram stain and culture of a colonized site, such as the conjunctivae, nose, throat, umbilicus, or perineum.
In SSSS, bacteria typically colonize one of these sites first, and the toxin then spreads hematogenously to cause the generalized rash.
For this reason, it’s not useful to culture fluid from one of the skin bullae! Unlike in bullous impetigo, lesions in SSSS don’t contain the causative bacteria, so cultures will be negative.
Now, if the biopsy shows a detached superficial epidermis, the Gram stain reveals gram-positive cocci in clusters, and the culture of a colonized site grows Staphylococcus aureus, you’ve confirmed the diagnosis of SSSS.
As for treatment, you’ll need to admit your patient to the hospital and administer intravenous antistaphylococcal antibiotics.
Since most strains of Staph. aureus produce penicillinases, be sure to choose a penicillinase resistant antibiotic like nafcillin or oxacillin; and if local prevalence of MRSA is high, consider treating with vancomycin.
Finally, provide IV fluids to replace fluid losses, place emollients and non-adherent dressings on denuded skin, and optimize pain management, such as analgesia and distraction techniques, especially during dressing changes.
Finally, consider topical mupirocin for decolonization of the nares if you suspect your patient is colonized with Staph.
Alright, as a quick recap… If a patient presents with a vesicular or bullous rash, assess for the Nikolsky sign. If negative, suspect impetigo.

Review 10:48–11:29

Nonbullous impetigo presents with vesicles and honey-colored crusts and can be treated with topical antibiotics for local disease or oral antibiotics for extensive disease.
Bullous impetigo presents with large, flaccid bullae, and is treated with oral antistaphylococcal antibiotics. A positive Nikolsky sign suggests Staphylococcal scalded skin syndrome, which is treated with intravenous antibiotics to cover penicillinase-producing
Staphylococcal scalded skin syndrome and impetigo | Osmosis