Effect of introducing two different concentrations of C. trachomatis EBs to urine before and after processing on the number of samples whose results fall below the test cutoff (false negative) by the LCx assay

No. of C. trachomatis EBs addedNo. of negative urine specimens/total no. of C. trachomatis EB-spiked urine specimens (%)
Before processingAfter processing
Original testRepeat test with 1:2 dilutionOriginal testRepeat test with 1:2 dilution
1002/70 (2.9)1/2 (50)2/70 (2.9)0/2 (0)
1234/70 (48.6)34/34 (100)21/70 (30)9/21 (42.8)