Antibody-coated bacteria in the urine of obstetrical patients with acute pyelonephritis

The direct immunofluorescence method for the detection of antibody-coated bacteria in urine sediments was used to test urine samples from obstetrical patients with the clinical diagnosis of acute pyelonephritis or cystitis. Antibody-coated bacteria were present in the urine from 12 of 15 patients with acute pyelonephritis, but they were not observed in the urine from 13 patients with cystitis. The clases of antibody coating the bacteria were IgG, IgA, and, in some cases, IgM. A correlation between a high titer of antibody in serum and the presence of antibody-coated bacteria in the urine was noted. These results confirm that the immunofluorescence test can be useful, as previously reported, in distinguishing infection of the kidney from infection of the bladder.