Particle size distribution analysis as a rapid method to detect significant bacteriuria

Particle size distribution analysis (PSDA) was evaluated as a rapid screening method for detecting significant bacteriuria by linking a C1000 Channelyzer to a Coulter Counter. Colony counts and PSDA screening results were compared for 800 urine specimens. The PSDA method proved to be 92% specific, but only 64% sensitive, for detecting at least 10(5) colony forming units (CFU)/ml. By performing serial dilution colony counts on 109 culture-positive specimens (greater than or equal to 10(5) CFU/ml), it was determined that the low level of sensitivity (64%) was due to culture-positive specimens that had between 10(5) and less than 10(7) CFU/ml. The sensitivity of the PSDA method increased to 90% and 100% when culture-positive specimens had 10(7) or more and 10(8) or more CFU/ml, respectively. The low level of sensitivity demonstrated in this investigation makes the introduction of this method into clinical usage unacceptable at this time.