Approach to bacterial causes of fever and rash (pediatrics): Clinical sciences

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Introduction 0:00–0:26

Fever and rash are common manifestations of bacterial infections in children. These infections are caused by a wide range of bacteria and can be either localized and mild or systemic and life-threatening.
Underlying causes can be categorized on the basis of rash morphology. If a pediatric patient presents with a chief concern suggesting a bacterial cause of fever and rash, first perform an ABCDE assessment to determine if the patient is unstable or stable.

Unstable Patient 0:26–1:36

If unstable, stabilize their airway, breathing, and circulation. Next, obtain IV access, give IV fluids, and put your patient on continuous vital sign monitoring, including blood pressure, heart rate, and pulse oximetry.
If needed, provide supplemental oxygen, and consider starting antibiotics. Now, here’s a clinical pearl to keep in mind!
The combination of fever and palpable purpura in an unstable patient should raise concern for meningococcemia, which is caused by Neisseria meningitidis.
On the other hand, fever with a generalized, sunburn-like rash can indicate toxic shock syndrome, which is typically caused by Staphylococcus aureus or Streptococcus pyogenes and is often associated with tampon use.
In both cases, it’s important to respond quickly and initiate empiric antibiotics, because your patient can quickly progress to shock.
Now that we’ve covered unstable patients, let’s go back to the ABCDE assessment and discuss stable patients. In this case, obtain a focused history and physical examination.

Stable Patient 1:36–2:02

History may reveal a sick contact or recent travel, while exam findings will include elevated temperature and a rash. To begin your evaluation, assess the rash morphology.
Let’s start with maculopapular and macular rashes, which might appear as annular, ring-shaped lesions, or distinct spots.

Maculopapular/Macular 2:02–2:16

The presence of annular lesions should make you think of erythema multiforme major and Lyme disease. First let’s discuss erythema multiforme major, or EM major.

EM Major 2:16–3:40

Patients may report headache, malaise, cough, or dyspnea. Physical exam might demonstrate exudative conjunctivitis, oral erosions, urethritis, or vaginitis.
You’ll also notice a rash consisting of multiple pink rings with an erythematous center, and possibly a central blister, often involving the palms and soles.
This rash is called erythema multiforme, which is a hypersensitivity reaction often triggered by viruses, medications, or the bacterium Mycoplasma pneumoniae.
With these findings, you should consider EM major, and obtain a chest X-ray and PCR testing for Mycoplasma pneumoniae. Chest X-ray findings of bilateral infiltrates and a positive Mycoplasma PCR confirm EM major due to Mycoplasma pneumoniae.
Now, here’s a clinical pearl to keep in mind! Erythema multiforme is categorized as EM major or EM minor.
Although both are associated with a similar rash appearance, EM major also includes mucosal involvement and systemic symptoms like fever, while EM minor only affects the skin.
Alright, let’s move on to Lyme disease. Affected patients might have a headache, myalgia, or arthralgia; and many report a tick exposure or live in or have traveled to a Lyme-endemic area.

Lyme Disease 3:40–4:36

Physical exam demonstrates an erythematous macule with partial central clearing that resembles a bull’s-eye, called erythema migrans.
With these findings, consider Lyme disease, which is caused by Borrelia burgdorferi, a spirochete carried by ticks. Your next step is to obtain serology testing for Borrelia burgdorferi.
Keep in mind that a serologic response may take two to four weeks to develop, so testing is not needed if your patient presents with early manifestations of Lyme disease.
When serology testing is indicated, a positive serology confirms a diagnosis of Lyme disease. Now, let’s look at lesions that appear as distinct pinkish macules called rose spots.

Typhoid 4:36–5:27

This type of rash should make you consider typhoid fever. Affected patients typically have a gradually rising fever, malaise, headache, abdominal pain, vomiting, and diarrhea; and some report recent travel.
Physical examination reveals bradycardia, hepatosplenomegaly, and rose spots on the trunk or abdomen. With these findings, consider typhoid fever, also known as enteric fever, which spreads through contaminated food and water.
Your next step is to obtain blood and stool cultures, and if either grows Salmonella typhi or paratyphi, diagnose typhoid fever.
Now, let’s switch gears and discuss patients with a rash consisting of plaques. This rash morphology should make you think of erysipelas.

Plaque 5:27–6:15

Affected patients typically have an acute onset of fever, malaise, and a painful rash. The physical exam reveals a localized rash with a well-demarcated, indurated area of erythema with an elevated border, that’s tender to palpation.
With these findings, consider erysipelas, which is an infection of the skin’s dermis layer. You can usually diagnose erysipelas clinically; but if you aren’t certain, obtain a Gram stain and culture.
If you see Gram-positive cocci in chains, and the culture grows group A streptococcus, diagnose erysipelas. Now, let’s discuss rashes that consist of diffuse papular erythema.

Diffuse papular erythema 6:15–7:58

This type of rash should make you think of scarlet fever. Affected patients are typically school-aged children with a sore throat, headache, and abdominal pain.
The physical exam often reveals circumoral pallor, palatal petechiae, and a strawberry tongue, as well as cervical lymphadenopathy.
The rash consists of generalized erythema, with fine papules that have a sandpapery texture, which typically spreads from the trunk, underarms, and groin, and then to the extremities.
You may also notice pastia lines, which are linear groups of papules found in skin folds like the neck or groin. At this point, consider scarlet fever, which is caused by an exotoxin produced by group A streptococcus.
Next, obtain a rapid strep test and consider a throat culture. If the rapid strep test is positive or the throat culture grows group A streptococcus, diagnose scarlet fever.
Now here’s a clinical pearl to keep in mind! Patients with untreated group A strep infection can develop a delayed sequela called acute rheumatic fever.
One feature of this condition is erythema marginatum, which is an erythematous rash on the trunk and proximal extremities, consisting of macules with a clear center and serpiginous borders with a creeping, wavy, and spreading pattern.
Acute rheumatic fever can be diagnosed using the Jones criteria and other minor criteria. Let’s switch gears and discuss rashes with vesicular, bullous, or pustular lesions.

Vesicular/Bullous/Pustular 7:58–9:24

In this case, you should think of impetigo, staphylococcal scalded skin syndrome, and rickettsialpox. First up is impetigo!
History usually reveals an infant or young child with a mildly pruritic rash. Examination reveals a rash consisting of vesicles on an erythematous base, most commonly around the nose, mouth, or extremities.
When these lesions rupture they form honey-colored crusts. In addition, regional lymphadenopathy may also be present.
These findings should make you consider impetigo. You can usually diagnose impetigo clinically, but if the diagnosis is unclear, consider ordering a Gram stain and culture of the skin lesions.
If the Gram stain shows gram-positive cocci in clusters or chains and if the culture grows Staphylococcus aureus or group A streptococcus, diagnose impetigo.
Here’s another clinical pearl! Neonates and young infants are more likely to develop bullous impetigo, which presents with fever and large, fluid-filled bullae that are caused by an exfoliative toxin produced by Staph.
aureus. Let’s move on to staphylococcal scalded skin syndrome, or SSSS.

SSSS 9:24–11:02

These patients 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 conjunctivitis, and a rash characterized by tender, generalized erythroderma that evolves into diffuse, flaccid, bullae.
The bullae rupture, leaving behind areas of moist, erythematous, denuded skin. You’ll often also see perioral and perinasal crusting and desquamation, with sparing of the mucosa; as well as a positive Nikolsky sign, meaning that applying lateral pressure to a bulla causes the upper skin layer to pull away from the underlying layers, to reveal a raw, red base.
With these findings, consider SSSS, which is caused by Staphylococcus aureus. To confirm the diagnosis, consider obtaining a skin biopsy and a Gram stain and culture of the colonized site, such as the conjunctivae, nose, throat, umbilicus, or perineum.
Biopsy of skin bullae reveals a detached superficial epidermis, while the Gram stain shows gram-positive cocci in clusters and the culture grows Staph.
aureus. With these findings, diagnose SSSS.
Next, let’s discuss rickettsialpox. History may reveal that the patient’s home has a known mouse infestation, or that they live in a crowded urban area.

Rickettsialpox 11:02–12:10

Some patients report fever, chills, headache, and malaise; and physical exam reveals lymphadenopathy. The rash initially appears as a single papule, with a central vesicle that later transitions to an eschar.
You will also notice papulovesicles on the trunk and proximal extremities. The triad of fever, vesicular rash, and eschar, along with the presence of mice in the patient’s environment should make you consider rickettsialpox, which is caused by Rickettsia akari.This bacterium is transmitted by the bite of a mite that lives on house mice.
You can usually diagnose rickettsialpox clinically, but serologic testing for R. akari is available; however, given the short course of the infection, serologic testing is rarely helpful in decision-making about treatment.
If you do order serologic testing, a positive serology confirms the diagnosis of rickettsialpox. Finally, let’s take a look at patients with petechial or purpuric rash.

Petechial/Purpuric 12:10–14:17

This rash should make you think of Rocky Mountain spotted fever. These patients may have a known tick exposure and typically have symptoms like fever, myalgia, headache, and malaise.
Patients will report that a rash developed 2 to 4 days after their fever began. The physical exam reveals a patient who is ill-appearing with a generalized rash that’s maculopapular at first and later becomes petechial.
The rash begins on the extremities, spreads to the trunk, and involves the palms and soles. With these findings, consider Rocky Mountain spotted fever, which is a tick-borne bacterial infection commonly seen in the Southeastern and South-central United States.
Your initial diagnosis is made clinically based on history, your patient’s potential for exposure to ticks, and physical exam findings.
If suspected, treatment should begin promptly! Then, confirm your diagnosis through serology for Rickettsia rickettsii, and if it’s positive, diagnose Rocky Mountain spotted fever.
Here’s a high-yield fact! Patients with Rocky Mountain spotted fever often have abnormal laboratory findings, such as thrombocytopenia, hyponatremia, and elevated liver enzymes!
And here’s one last clinical pearl! Some sexually transmitted infections present with fever and variable rash morphology.
For example, disseminated infection caused by Neisseria gonorrhea can manifest with generalized pustules, papules, vesicles, or petechiae; often in the absence of classic symptoms like vaginal or urethral discharge or pain.
Similarly, secondary syphilis typically occurs months after the initial chancre of primary syphilis resolves, and manifests with fever and a widespread papular, papulovesicular, or maculopapular rash involving the palms and soles.
Remember to consider these diagnoses in sexually active patients with fever and a generalized rash! Alright, as a quick recap… If you suspect a bacterial cause of fever and rash, obtain a history and physical examination, and assess the rash characteristics.

Review 14:17–15:06

Maculopapular or macular rashes with annular lesions are associated with erythema multiforme major and Lyme disease; whereas rose spots suggest typhoid fever.
Rashes characterized as plaques might indicate erysipelas, while diffuse erythroderma suggests scarlet fever. Vesicular, bullous, and pustular lesions suggest impetigo, Staphylococcal scalded skin syndrome, or rickettsialpox.
Finally, petechial or purpuric rashes are associated with