TABLE 2.

Effect of storage and retesting of urine specimens to which C. trachomatis was introduced before processing by the APTIMA Combo 2 and LCx assaysa

DilutionNo. of negative urine specimens/no. of false-negative specimens after addition of C. trachomatis EBs (%)
APTIMA Combo 2 assayLCx assayb with 12 EBs
12 EBs1 EB
Neat0/2 (0)2/7 (28.6)19/40 (47.5)
1:40/2 (0)2/7 (28.6)18/40 (45.0)
False-negative result reduction0/415 (0)2/244 (0.8)18/334 (5.4)
  • a The specimens were kept at 4°C overnight.

  • b There was sufficient volume to retest only 40 of 44 false-negative urine specimens by the LCx assay.