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To the Editor:—
In the collection of a urine specimen for culture, great emphasis is placed on plating out the specimen immediately, lest there be gross error in the colony count from bacterial multiplication while the urine sits on the shelf. Yet the physician rarely questions either the length of time the urine remains in the bladder (ie, the time of previous voiding) or the specific gravity of the urine. A person with a urinary tract infection may have urinary frequency both from the irritability of the inflamed bladder as well as from a high fluid intake, thereby decreasing the time of previous voiding as well as the specific gravity of the urine. Both of these would decrease the colony count.A series of patients with cystitis were subjected to sequential urine cultures in an attempt to compare the effect on colony count of incubation in the bladder with that
Marshall S, Lyon RP. Pitfalls of Colony Count Of Urine Cultures. JAMA. 1968;204(7):634-635. doi:10.1001/jama.1968.03140200074030