Question

acute pyelonephritis is most often caused by:
viruses
immune complex deposition
gram-negative bacteria
gram-positive bacteria

Explanation:

Acute pyelonephritis is a kidney infection. Most cases are caused by Gram - negative bacteria, especially Escherichia coli (E. coli) which ascend from the lower urinary tract. Viruses rarely cause pyelonephritis, immune complex deposition is more related to glomerulonephritis, and Gram - positive bacteria are less common causes compared to Gram - negative ones.

Answer:

C. Gram - negative bacteria