Antibody-Coated Bacteria in the Urine and the Site of Urinary-Tract Infection

An immunofluorescence test for the detection of antibody-coated bacteria in urinary sediments of patients with urinary-tract infections was studied for its predictive value in determining the site of infection. Antibody-coated bacteria were observed in urine specimens from 34 of 35 patients with pyelonephritis; they were not observed in urines from 19 of 20 patients with cystitis. Most of the patients (20 of 28) with antibody-coated bacteria in the urine had high serum antibody titers against their own infecting bacteria. These results suggest that the immunofluorescence test can be useful in distinguishing infection of the kidney from infection of the bladder. (N Engl J Med 290:588–590, 1974), A SIMPLE, reliable, and risk-free technic for distinguishing infection of the kidney from infection of the bladder would provide a useful aid in the treatment and management of urinary-tract infections. One experimental approach to such a technic is based on demonstration of the patient's immune response against his own infecting bacteria. Using passive hemagglutination and bacterial agglutination, investigators have attempted to correlate the patient's serum antibody titer with the site of urinary-tract infection.^{1 2 3} Although elevated serum antibody titers were found more commonly in patients with pyelonephritis than in those with cystitis, many patients with pyelonephritis did not respond to their.