USMLE Review- 10

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Q- A 15-year-old boy is diagnosed with “Walking pneumonia”. Which of the following is the most effective treatment of this condition?

A- Ampicillin

B- Azithromycin

C- Tetracycline

D- Vancomycin

B- Azithromycin- Walking pneumonia is atypical pneumonia most commonly caused by Mycoplasma and Chlamydia. Macrolides such as azithromycin are the treatment of choice for these organisms.



Q- A patient is brought to the emergency room in a deep coma following a motor car accident. Vital signs, general examination and local chest and abdominal examinations are normal. Head CT scan is normal. Which of the following is the most likely initial diagnosis?

A-Cerebral contusion

B- Diffuse axonal injury

C- Epidural hematoma

D- Subdural hematoma

B- Diffuse axonal injury- This is the only lesion on the list that is not evident on CT scan of the head. MRI would show diffuse white matter disruption.



Q- Which one of the following enzymes catalyzes the rate limiting step in glycolysis?

A- 6-Phosphofructo-1 kinase

B- Glyceraldehyde-3-phosphate dehydrogenase

C- Phosphofructokinase-2

D- Pyruvate kinase

A- PFK-1 (6-phosphofructo-1 kinase) catalyzes the rate limiting step in glycolysis. Citrate and ATP inhibits its activity while AMP activates it and so, it limits glycolysis.

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