Master the board step 3

Master the Boards: USMLE Step 3
Infectious Disease
Fever without a Focus in the Young Child
Fever (temperature of > 38°C/100.4°F rectally) without focus lasts < 1 week and
occurs in children < 36 months old. It is not the same as “fever of unknown
origin,” which has been present for > 3 weeks.
Treatment
Give empiric antibiotics under the following conditions:
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Documented rectal temperature > 38°C/100.4°F
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WBC > 15,000, neutrophils > 1,500 with band forms
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Neonate: Hospitalize, pan-culture (blood, urine), and give prophylactic
antibiotics to cover for group B Streptococcus, E. coli, and Listeria
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Infant: Most common organism is Streptococcus pneumoniae
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Well appearing: Give single-dose IM ceftriaxone and follow up in 24
hours
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Toxic appearing: Start empiric IV antibiotics
Meningitis
A 5-month-old child presents with lethargy, poor feeding, and irritability. He has
been vomiting for 2 days and has had a temperature of 101.3°F. On exam, the
fontanelles are noted to be bulging, and there is paralysis of the lateral gaze on
the left side. The mother reports that he is up-to-date on all vaccinations. Which
of the following is the next step in management?
a. CT scan of the head
b. Empiric antibiotics
c. Lumbar puncture
d. Steroids
e. Urine culture
Answer: B. This history is highly suggestive of meningitis. However, the patient is also
exhibiting signs of increased intracranial pressure, a contraindication to lumbar puncture
(workup of meningitis includes blood culture and lumbar puncture, unless there are
signs of ICP). CT scan is not sensitive in diagnosing increased ICP or meningitis. It is not
required for the initiation of antibiotics when clinical suspicion is high. The most important
next step in management is to begin empiric antibiotics based on clinical suspicion.
Intravenous dexamethasone has been shown to be of value in management of meningitis
due to HiB. However, HiB is uncommon in the United States with the advent of vaccines,
which protect infants against HiB infections.
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