title: The verification of nucleic acid amplification testing (Gen-Probe Aptima Assay) for chlamydia trachomatis from ocular samples.
abstract: OBJECTIVE
  Chlamydia trachomatis conjunctivitis may present with extended symptoms, and it can have social ramifications as a sexually transmitted disease. For appropriate therapy, C. trachomatis conjunctivitis should be diagnosed definitively. This study presents the verification of nucleic acid amplification testing (NAAT; Gen-Probe Aptima Combo 2 assay) for detection of C. trachomatis ribosomal RNA (rRNA) from direct ocular samples.
  
  
  METHODS
  Retrospective laboratory verification study.
  
  
  METHODS
  Patients with infectious conjunctivitis.
  
  
  METHODS
  A battery of 25 true-positive specimens (direct ocular specimens from patients with symptoms consistent with C. trachomatis conjunctivitis and with previously demonstrated positive polymerase chain reaction [PCR] results for C. trachomatis DNA by Roche Amplicor) and 25 true-negative specimens (direct ocular specimens with culture-positive results for herpes simplex virus [n = 5], adenovirus [n = 5], Haemophilus influenzae [n = 5], and Streptococcus pneumoniae [n = 5]), and transport medium (n = 5) were tested for C. trachomatis rRNA by NAAT. These true-negative specimens have differential etiologic agents of infectious conjunctivitis. The 25 C. trachomatis specimens with PCR-positive results (obtained May 1994-May 2012) and 20 true-negative infectious ocular specimens (obtained December 2008-August 2013) were collected with soft-tipped applicators and placed in transport medium. All excess specimens were stored at -80°C. All samples were centrifuged at 13,000 rpm for 1 hour at 6°C. For each sample, using the Aptima Unisex collection blue swab, a specimen was collected from the conical apex of the storage tube where a pellet was formed. The Aptima Unisex collection swab was placed in a tube of Aptima swab transport medium for testing. All samples were tested in duplicate.
  
  
  METHODS
  Detection of C. trachomatis rRNA.
  
  
  RESULTS
  Of 25 true-positive samples, 24 (96%) were positive by NAAT, whereas 25 of 25 true-negative samples (100%) showed negative results. The sensitivity, specificity, positive predictive value, negative predictive value, and efficiency were determined to be 96%, 100%, 100%, 96%, and 98%, respectively.
  
  
  CONCLUSIONS
  The detection of C. trachomatis in ocular specimens by NAAT was verified for laboratory diagnosis. The test will be evaluated prospectively to determine future test performance precisely.
authors.affiliation: The Charles T. Campbell Eye Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania. Electronic address: kowalskirp@upmc.edu.
authors.forename: Regis P
authors.initials: RP
authors.lastname: Kowalski
authors.affiliation: The Charles T. Campbell Eye Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Karenchak
authors.affiliation: The Charles T. Campbell Eye Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Leela V
authors.initials: LV
authors.lastname: Raju
authors.affiliation: Division of Clinical Microbiology, Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Nahed
authors.initials: N
authors.lastname: Ismail
mesh_terms: D002690:Chlamydia Infections / Q000175:diagnosis* / Q000382:microbiology; D002692:Chlamydia trachomatis / Q000235:genetics / Q000302:isolation & purification*; D003228:Conjunctiva / Q000382:microbiology*; D003235:Conjunctivitis, Inclusion / Q000175:diagnosis* / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D015818:Eye Infections, Bacterial / Q000175:diagnosis* / Q000382:microbiology; D005189:False Positive Reactions; D006801:Humans; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D012335:RNA, Ribosomal / Q000235:genetics; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D004269:DNA, Bacterial; D012335:RNA, Ribosomal