Pyelonephritis, cortical abscess, and perinephric abscess.

The causative agent in nonobstructive pyelonephritis has been shown most often to be P-fimbriated Escherichia coli, mainly because receptors for these fimbriae are found in the bladder, ureter, and the kidney tubules. Age and sex are factors leading to differences in the presentation of the disease, and early diagnosis followed by intensive therapy lessens the chance of renal damage. Renal abscess, perinephric abscess, and pyonephrosis all follow pyelonephritis in the host who is compromised by the presence of stone, obstruction, diabetes, or immunosuppression.