title: Real-time polymerase chain reaction shows that density centrifugation does not always remove Chlamydia trachomatis from human semen.
abstract: OBJECTIVE
  To evaluate the efficiency of sperm washing procedures to remove Chlamydia trachomatis from semen both in clinical samples and experimental inoculations.
  
  
  METHODS
  Laboratory-based study.
  
  
  METHODS
  Research laboratory in a university hospital.
  
  
  METHODS
  One hundred men attending for diagnostic semen analysis as part of infertility investigations and three sperm donors providing ejaculates for research purposes.
  
  
  METHODS
  Number of DNA copies of C. trachomatis, infectivity in an HeLa cell monolayer, and immunofluorescence.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Henry Wellcome Laboratories for Medical Research, Unit of Infection and Immunity, School of Medicine and Biomedical Sciences, The University of Sheffield, The Jessop Wing, Royal Hallamshire Hospital, Sheffield, United Kingdom.
authors.forename: Najwa
authors.initials: N
authors.lastname: Al-Mously
authors.forename: Neil Alan
authors.initials: NA
authors.lastname: Cross
authors.forename: Adrian
authors.initials: A
authors.lastname: Eley
authors.forename: Allan Anthony
authors.initials: AA
authors.lastname: Pacey
mesh_terms: D002499:Centrifugation, Density Gradient / Q000379:methods; D002690:Chlamydia Infections / Q000175:diagnosis / Q000235:genetics / Q000382:microbiology*; D002692:Chlamydia trachomatis / Q000166:cytology / Q000302:isolation & purification*; D004269:DNA, Bacterial / Q000032:analysis / Q000302:isolation & purification; D004526:Efficiency; D006367:HeLa Cells; D006801:Humans; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D012661:Semen / Q000382:microbiology*; D055101:Semen Analysis / Q000379:methods; D012662:Semen Preservation / Q000379:methods; D012680:Sensitivity and Specificity
chemical_list: D004269:DNA, Bacterial