ABIM Exam Review Practice Question of the Week: 28-year-old allergic to amoxicillin gets bitten by a cat

28-year-old female comes to the ED after she incurs a deep wound cat bite. The wound is cleaned in the department. Redness surrounding the wound is noted.


A few years ago, she was given amoxicillin for sinus infections and experienced severe throat closing and rash all over the body. She received a tetanus booster three years ago. Which of the following is the most appropriate antibiotic therapy to give this patient at this time?


A. Metronidazole


B. Azithromycin and metronidazole


C. Doxycycline and metronidazole


D. Azithromycin and trimethoprim-sulfamethoxazole


E. Amoxicillin-clavulanate


Explanation When a patient gets bit by a cat and develops an infection, the most common organism implicated is pasteurella.


Let’s go over the answer choices to identify the best treatment against Pasteurella. Choice A (Metronidazole) is incorrect because this antibiotic should not be used alone as it only covers anaerobes. Choice B (Azithromycin and metronidazole) is incorrect since azithromycin is not recommended for wound infections. Choice C (Doxycycline and metronidazole) is the best answer at this time. Choice D (Azithromycin and TMP/SMZ) is incorrect because even though TMP/SMZ is appropriate to use, azithromycin is not used as a treatment for this type of infection. Choice E (Amoxicillin-clavulanate) is generally the first-line therapy for cat bite infections (similar to human bite wounds). This patient, however, has had anaphylaxis to penicillin so this agent should not be used here.


You can see all the previous ABIM Exam Review Questions of the Week at the Knowmedge Blog. You can find also additional topics and questions directly from the Knowmedge Internal Medicine ABIM Board Exam Review Questions QVault.

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