Positive Foley catheter tip cultures--fact or fancy?

Forty of 42 patients had positive Foley catheter tip cultures, but only 14 had significant numbers of bacteria in a urine specimen obtained the same day. In these 14 patients, a 98% probability existed that at least one organism from the catheter tip culture would not grow in a simultaneous urine culture. The predictive value of the tip cultures was nonexistent; presence of most organisms in the tip probably represented contamination from the urethra. (JAMA228:72-73, 1974)