Bacteriuria in the catheterized patient. Cystitis or pyelonephritis?

Seventy-two patients with indwelling urethral catheters had urine specimens cultured to detect bacteriuria. Bacterial sediments were examined to find the source of the bacteria, with use of an antibody immunofluorescence (IF) technique. Antibody coating demonstrated by fluorescence was considered evidence for pyelonephritis. In cystitis, the bacteria did not fluoresce. Repeat culture and immunofluorescence studies were done 3 to 18 week later. One third of the patients had a urinary infection. Two (13%) of the patients catheterized for one day and 17 (55%) catheterized four or more days had appreciable bacteriuria. One patient catheterized less than three days had positive IF, while 5 patients (16%) catheterized four or more days had positive IF. Only two of the ten patients observed, with an initial infection, had sterile urine on follow-up culture. On follow-up study, of the four patients with bacteriuria of renal origin, one showed a sterile urine, two had cystitis, and one still had pyelonephritis.