MKSAP Quiz: ear pain following URI
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EDITOR’S NOTE: ACP InternistWeekly now features questions from MKSAP 15. See the Answer and Critique for this question for important information about MKSAP 15.
A 45-year-old man is evaluated because of the acute onset of right ear pain. The patient was well until 10 days ago, when he developed symptoms of an upper respiratory tract infection, including nasal congestion and a nonproductive cough. Although these symptoms are resolving, pain and some loss of hearing in the right ear first occurred last night. He does not have fever, sore throat, or drainage from the ear. Medical history is unremarkable. The patient has no allergies and takes no medications.
On physical examination, vital signs, including temperature, are normal. The right tympanic membrane is erythematous, opacified, and immobile, but the external auditory canal is normal. The left ear and posterior pharynx are normal. Examination of the chest is unremarkable.
Which of the following is the best initial antibiotic choice in this patient?
A. Amoxicillin
B. Amoxicillin-clavulanate
C. Azithromycin
D. Ceftriaxone
MKSAP Answer and Critique
The correct answer is A) Amoxicillin. This item is available online to MKSAP 15 subscribers in the General Internal Medicine section, Item 2.
The best initial antibiotic for this patient is amoxicillin. Although otitis media is the most frequent bacterial infection in children, it is much less common in adults. In most cases of acute otitis media, a viral upper respiratory tract infection precedes the ear infection. Eustachian tube obstruction occurs secondary to inflammation. Bacteria subsequently enter the middle ear by means of a compliant eustachian tube, aided by other factors, including nose blowing, sniffing, and negative middle ear pressure. The microbiology of otitis media in adults is similar to that of children: Streptococcus pneumoniae, 21% to 63%; Haemophilus influenzae, 11% to 26%; Staphylococcus aureus, 3% to 12%; and Moraxella catarrhalis, 3%. Thirty percent of bacterial cultures of the middle ear show no growth.
Antibiotic therapy should be reserved for patients in whom evidence of purulent otitis exists. There are no antibiotic treatment trials in adults. Guidelines for antibiotic use are the same in children and adults. Amoxicillin is the recommended initial antibiotic because of its proven efficacy, safety, relatively low cost, and narrow spectrum of activity. If symptoms do not improve after 48 to 72 hours of amoxicillin therapy, initiation of amoxicillin-clavulanate, cefuroxime, or ceftriaxone is recommended. Alternative agents for patients with penicillin allergy are oral macrolides (azithromycin, clarithromycin). Patients should not use nasal decongestants or antihistamines. Follow-up of these patients is not necessary unless symptoms persist or progress.
Key Point
- Amoxicillin is the recommended antibiotic for treating acute otitis media in adults because of its proven efficacy, safety, relatively low cost, and narrow spectrum of activity.