Real-time polymerase chain reaction shows that density centrifugation does not always remove Chlamydia trachomatis from human semen.

OBJECTIVE

To evaluate the efficiency of sperm washing procedures to remove Chlamydia trachomatis from semen both in clinical samples and experimental inoculations.

DESIGN

Laboratory-based study.

SETTING

Research laboratory in a university hospital.

PATIENT(S): One hundred men attending for diagnostic semen analysis as part of infertility investigations and three sperm donors providing ejaculates for research purposes.

MAIN OUTCOME MEASURE(S): Number of DNA copies of C. trachomatis, infectivity in an HeLa cell monolayer, and immunofluorescence.

RESULT(S): Of the 100 semen samples examined, 13 contained detectable levels of C. trachomatis DNA (675-15,920 copies/mL) and in only 7 was this completely removed after sperm washing. In the remaining six DNA-positive samples, the number of copies in the postwash preparation ranged from 36-455 per mL. Experimental inoculations found that postwash preparations containing C. trachomatis DNA as low as 61 copies/mL were able to establish an infection in vitro.

CONCLUSION(S): Undiagnosed C. trachomatis infections in men attending for assisted conception could potentially lead to infection or contamination of the IVF culture system as sperm washing methods are not 100% effective.