Evaluation of the APTIMA Combo 2™ kit for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae in frozen semen

Abstract

Detection of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) in cryopreserved semen is crucial for screening sperm donors. The evaluation of the limit of detection (LOD) of the APTIMA Combo 2™ kit (Panther, Hologic) was performed on cryopreserved semen samples spiked with CT and NG at concentrations ranging from 1 to 106 IFU/mL or CFU/mL, respectively. The LOD was 102 IFU/mL for CT and 10 CFU/mL for NG in single infection or coinfection. An inhibitory effect of semen on amplification was highlighted. This study confirmed the performance of the APTIMA Combo 2™ kit for screening cryopreserved sperm samples before donation.

Keywords: Chlamydia trachomatis; Neisseria gonorrhoeae; Cryopreserved semen; NAAT.

Fig. 1

Relative light unit (RLU) measurements in the IFU number per mL of CT in glycerol semen (S) and UTM control (U) at different test portion. Interpretation according to supplier data: CT only, negative if RLU < 25, equivocal for 25 < RLU < 100 and positive if RLU > 100. (Results are expressed in mean and standard deviation from 3 independent experiments)

Fig. 2

Results of relative light unit (RLU) measurements as a function of bacterial count per mL of NG or CT in glycerol sperm medium (Sperm) and UTM control (UTM), for a 150µL sample. Interpretation according to supplier data: NG only, negative if RLU < 60, equivocal for 60 < RLU < 150 and positive if RLU > 150; NG in co-infection, negative if RLU < 85, equivocal for 85 < RLU < 250 and positive if RLU > 250; CT only, negative if RLU < 25, equivocal for 25 < RLU < 100 and positive if RLU > 100; CT in co-infection, negative if RLU < 85, equivocal for 85 < RLU < 250 and positive if RLU > 250. (Results are expressed in mean and standard deviation from 3 independent experiments)