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

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. 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. 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.

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. 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. 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. 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. 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. 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.