Which bacterium causes erythema migrans after a tick bite in the northeastern United States?
Answer and explanation
Correct answer: A. Borrelia burgdorferi
- Step 1: An expanding annular rash at the bite site is erythema migrans. Step 2. It is the sign of Lyme disease, transmitted by Ixodes ticks. Answer: Borrelia burgdorferi. Why not the others: Rickettsia causes Rocky Mountain spotted fever with a peripheral rash, and the other organisms cause different illnesses.
Practise more Microbiology and Infectious Disease.
Free questions with an explanation for every one, and full timed USMLE Step 1 mock tests.
More Microbiology and Infectious Disease questions
- A newborn has conjunctivitis 3 days after delivery. The Gram stain shows gram-negative intracellular diplococci. Which organism is responsib…
- Which organism is the most common cause of community-acquired pneumonia in adults?
- A 22-year-old man has a sore throat, fever, posterior cervical lymphadenopathy and splenomegaly. Atypical lymphocytes are seen on the smear.…
- A farmer has a painless black eschar on the arm with surrounding edema. The Gram stain of the lesion shows large gram-positive rods. Which o…
- A 25-year-old woman has dysuria and frequency. Urine culture grows a lactose-fermenting gram-negative rod that forms pink colonies on MacCon…
- A man with a urinary catheter develops a urinary infection with alkaline urine and struvite stones. Which organism produces urease and cause…