USMLE Forum Archives - USMLE Step 2 CK - IM 46
IM 46
TheOne - 06-25-07 14:51
A 28 year old tire salesman complains of a low-grade fever and a nonproductive cough for 1 week. His girlfriend had similar symptoms 1 week earlier. He denies any shortness of breath or pleuritic chest pain. On physical examination, his temperature is 38.2 C (102.2 F). A lung examination reveals coarse bilateral inspiratory and expiratory crackles. His laboratory results reveal a white blood cell count of 7000/mm3, a hemoglobin of 10.2 g/dL, and a hematocrit of 34%. A cold agglutinin assay of his red blood cells is positive. Which of the following is the most appropriate treatment for this patient?
A. Ampicillin
B. Cephalexin
C. Doxycycline
D. Tetracycline
E. Trimethoprim/sulfamethoxazole
TheOne - 06-25-07 14:51
A 28 year old tire salesman complains of a low-grade fever and a nonproductive cough for 1 week. His girlfriend had similar symptoms 1 week earlier. He denies any shortness of breath or pleuritic chest pain. On physical examination, his temperature is 38.2 C (102.2 F). A lung examination reveals coarse bilateral inspiratory and expiratory crackles. His laboratory results reveal a white blood cell count of 7000/mm3, a hemoglobin of 10.2 g/dL, and a hematocrit of 34%. A cold agglutinin assay of his red blood cells is positive. Which of the following is the most appropriate treatment for this patient?
A. Ampicillin
B. Cephalexin
C. Doxycycline
D. Tetracycline
E. Trimethoprim/sulfamethoxazole
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#1
Re: IM 46 jwang - 06-25-07 23:29 It sounds like he has "walking pneumonia" aka mycoplasma pneumonia. Usually treated with a macrolide but thats not one of the choices. I'd maybe go with a tetracycline since he is old enough to not have problems with it. Now the question is which tetracycline. Hm.. I'll just go with D.
#2
Re: IM 46
TheOne - 07-08-07 15:45 The correct answer is C. This patient has the typical findings of an atypical pneumonia, with low-grade fevers and a bilateral infiltrate without a productive sputum. The cold agglutinin assay is positive, indicating that the underlying infection is Mycoplasma pneumonia. This is also the explanation for his anemia, since he is agglutinating red cells at cold temperatures. The appropriate antibiotic for Mycoplasma is oral doxycycline.
Although the other antibiotics, ampicillin (choice A), cephalexin (choice B), and trimethoprim/sulfamethoxazole (choice E), are appropriate broad-broad spectrum antibiotics for community-acquired pneumonias, they are not effective against the atypical pneumonias. Tetracycline (choice D) is not generally considered a first line therapy for Mycoplasma pneumonia.
#3
Re: IM 46 bingousmle - 06-20-10 08:08 cold agglutinin test positive and fever with coarse bilateral inspiratory and expiratory crackles suggests mycoplasma pneumonia give doxy
#4
Re: IM 46 babbu5508 - 06-20-10 13:43 C. Doxycycline...for atypical pneumonia due to mycoplasma...evidenced by positive cold agglutinin assay of his red blood cells .....
#6
Re: IM 46 bingousmle - 06-30-10 18:02 here the patient has cold agglutinins.. a related high yield topic frequently tested is where are the warm agglutinins found
#7
Re: IM 46 babbu5508 - 07-10-10 03:23 C. Doxycycline.....a cold agglutinin assay of his red blood cells is positive in the case of atypical pneumonia due to mycoplasma...
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