Master the board step 3

Master the Boards: USMLE Step 3
Sinusitis
Look for a patient with nasal discharge, headache, facial tenderness, tooth
pain, bad taste in the mouth, and decreased transillumination of the sinuses.
Most cases are viral, but bacterial causes include the same group that
cause otitis media: Streptococcus pneumoniae, Haemophilus influenzae, and
Moraxella catarrhalis.
Diagnostic Testing
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Best initial test: x-ray
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Most accurate test: Sinus aspirate for culture. This is more accurate than a
CT or MRI; you cannot stain or culture a radiologic test.
Treatment
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Same as for otitis media, but add inhaled steroids
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Use amoxicillin/clavulanate if there is
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fever and pain;
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persistent symptoms despite 7 days of decongestants; and
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purulent nasal discharge.
Basic Science Correlate
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N
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COOH
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CH 2
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Clavulanic acid (pictured here) is a beta-lactamase inhibitor that confers a
broader spectrum of antimicrobial activity to penicillin. Clavulanic acid is
similar in structure to the beta-lactam ring of penicillin. The enzyme beta
lactamase destroys the clavulanic acid instead of the penicillin. This is why it
is a “suicide inhibitor.” The other beta-lactamase inhibitors, tazobactam and
sulbactam, work the same way.
Pharyngitis
The diagnosis of streptococcal pharyngitis is certain if the following are present:
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Pain/sore throat
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Exudate
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Adenopathy
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No cough/hoarseness
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