Diagnostic Test Directory

Virology Laboratory

Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) by molecular amplification - rectal specimen

  • LIS Mnemonic: CTGCMA


    RECTAL SWAB SPECIMEN - Insert a Dacron-tipped, plastic-shafted swab approximately 3 cm into the anal canal. Move the swab from side to side to sample crypts. If possible, avoid gross fecal contaminat

    Volume Required


    Minimum Required



    Specimens should be refrigerated (4C) immediately after collection and during storage and transport. Send swabs in viral/chlamydial transport medium. Viral/chlamydial transport medium can be obtained directly from the Clinical Virology Laboratory or from Central Laboratory Services.




    Specimen collection is critical for sensitive detection of C. trachomatis and specimens should be taken with sufficient force to obtain adequate numbers of columnar epithelial cells from the site.

    Unacceptable conditions

    Swab specimens not received in viral/chlamydial transport medium or received in bacteriological transport medium are discouraged. DO NOT USE CALCIUM ALGINATE OR WOODEN SHAFT SWABS FOR COLLECTION OF SPECIMENS; ONLY USE DACRON OR RAYON TIPPED SWABS ON PLASTIC OR METAL SHAFTS.

Days Performed

Mon, Wed, Fri



Reflex Testing

Test for Neisseria gonorrhoeae is performed in combination with the test for C. trachomatis. Positive results obtained for either C. trachomatis or N. gonorrhoeae when using the GenProbe APTIMA Combo 2 Assay will be confirmed using a second supplemental molecular amplification assay that detects a nucleic acid sequence different from that detected in the initial screening assay.


87801 (Combo) 87491 (CT supplemental) 87591 (GC supplemental)


The GenProbe APTIMA Combo 2 Assay uses transcription-mediated amplification (TMA) to replicate a specific region of the 23S rRNA from C. trachomatis and a specific region of the 16S rRNA from N. gonorrhoeae via DNA intermediates. A unique set of primers is used for each target molecule.

Disease Information


The GenProbe APTIMA Combo 2 Assay is designed to detect the presence of C. trachomatis and N. gonorrhoeae in clinician-collected endocervical, vaginal, and male urethral swab specimens, patient-collected vaginal swab specimens, and in female and male urine specimens. The assay is also intended for use with testing of gynecological specimens collected in the PreserCyt Solution and processed with the Cytyc ThinPrep 2000 System. The assay may be used to test specimens from symptomatic and asymptomatic individuals to aid in the diagnosis of gonococcal and/or chlamydial urogenital specimens. Alternative specimen sources such as conjunctival, nasopharyngeal and rectal specimens can also be tested using this assay for newborns or infants with suspected conjunctivitis and/or pneumonia due to infection with C. trachomatis during birth and for anorectal infections in women and men. Lastly, the test is applicable for the detection of C. trachomatis and/or N. gonorrhoeae in investigating sexual assault and abuse. Additional testing will be done to confirm any initial positive results in this patient population.


If positive, results are reported as Chlamydia trachomatis rRNA detected or Neisseria gonorrhoeae rRNA detected or both Chlamydia trachomatis rRNA and

Reference Values

Negative or no Chlamydia trachomatis rRNA detected. Negative or no Neisseria gonorrhoeae rRNA detec

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