Effect of delay on culture of urine.

One hundred random urine specimens which were submitted for culture were planted using a calibrated loop within 2 h of collection and 2 and 4 h later after standing at room temperature. Colonies were counted after an 18- to 24-h incubation at 37 degrees C. Fifteen of the specimens demonstrated increases in counts exceeding 1 X log10; four increased from less than 10(5)/ml to greater than 10(5)/ml (three by the 4-h culture and a fourth by the 6-h culture), supporting the concept that delays of greater than 2 h in inoculating cultures may produce results which could cause errors in diagnosis.