Chlamydia Trachomatis & Neisseria Gonorrhoeae (CT/NG)

The cobas® 4800 CT/NG Test is an in vitro nucleic acid amplification test for the qualitative detection of Chlamydia trachomatis (CT) and/or Neisseria gonorrhoeae (NG) in patient specimens. The test allows for detection of CT/NG DNA in endocervical and vaginal swab specimens, and male and female urine in cobas® PCR Media. The intended targets for the cobas® 4800 CT/NG Test include all fifteen major Chlamydia trachomatis serovars, the Swedish C. trachomatis mutant (nvCT), and both wild-type and variant DR-9 sequences of N. gonorrhoeae.

CT and/or NG Detected

Not Detected

Invalid

Limitations of Test

• The cobas® 4800 CT/NG Test has only been validated for use with female endocervical swab and clinician collected vaginal swab and clinician-instructed self-collected vaginal swab specimens collected in cobas® PCR Media (UT), female and male urine specimens stabilized in cobas® PCR Media (UUT).
• Interfering substances include, but are not limited to the following:
  
  • The presence of mucus in endocervical and cervical specimens may inhibit PCR and cause false negative test results. Mucus free specimens are required for optimal test performance. Use a sponge or an additional swab to remove cervical secretions and discharge before obtaining the specimen.
  • Urine specimens stabilized in cobas® PCR Media containing greater than 0.35% (v/v) blood may give false negative results.
  • Endocervical swab specimens, vaginal swab specimens and cervical specimens, each containing up to 5% (v/v) whole blood exhibited no interference effects. Whole blood levels above 5% (v/v) may give invalid or false negative results.
  • Endocervical swab specimens, vaginal swab specimens and urine specimens, all stabilized in cobas® PCR Media and containing greater than 1 x 105 PBMC cells/mL may give invalid or false negative results.
  • Urine specimens taken from patients who have used the over-the-counter product Replens® vaginal moisturizer may give invalid or false negative results.
  • Urine specimens taken from patients who have used the over-the-counter product RepHreshTM Odor Eliminating Vaginal Gel and RepHreshTM Clean Balance may give invalid or false negative results.

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• Detection of C. trachomatis and N. gonorrhoeae is dependent on the number of organisms present in the specimen and may be affected by specimen collection methods, patient factors (i.e., age, history of STD, presence of symptoms), stage of infection and/or infecting C. trachomatis and N. gonorrhoeae strains.
• False negative results may occur due to polymerase inhibition. The CT/NG Internal Control is included in the cobas® 4800 CT/NG Test to help identify specimens containing substances that may interfere with nucleic acid isolation and PCR amplification.
• Prevalence of infection in a population may affect performance. Positive predictive values decrease when testing populations with low prevalence or individuals with no risk of infection. Because the prevalence of C. trachomatis and N. gonorrhoeae may be low in some populations or patient groups, a false positive rate can exceed the true positive rate so that the predictive value of a positive test is very low. Since some patients that are truly infected will not be identified by testing a single specimen, the true rate of false positives cannot be determined or presumed from the clinical data. The rate of false positive test results may depend on training, operator ability, reagent and specimen handling or other such factors in each laboratory.
• Reliable results are dependent on adequate specimen collection, transport, storage and processing. Follow the procedures in the Package Insert.
• The cobas® 4800 CT/NG Test is not recommended for evaluation of suspected sexual abuse and for other medico-legal indications.
• The cobas® 4800 CT/NG Test provides qualitative results. No correlation can be drawn between the Ct value reported for a positive cobas® 4800 CT/NG Test and the number of C. trachomatis and N. gonorrhoeae cells within the infected specimen.
• The cobas® 4800 CT/NG Test for male and female urine testing is recommended to be performed on first catch urine specimens (defined as the first 10 to 50 mL of the urine stream). The effects of other variables such as first-catch vs. midstream, post-douching, etc. have not been evaluated.
• Improperly collected endocervical swab specimens are likely to contain excess mucus, which may cause clots on the cobas® 4800 System.
• The effects of other potential variables such as vaginal discharge, use of tampons, douching, etc. and specimen collection variables have not been evaluated.
• The cobas® 4800 CT/NG Test is not intended to replace cervical exam and endocervical sampling for diagnosis of urogenital infection. Patients may have cervicitis, urethritis, urinary tract infections, or vaginal infections due to other causes or concurrent infections with other agents.
• Though rare, mutations within the highly conserved regions of the cryptic plasmid or genomic DNA of C. trachomatis or the genomic DNA of N. gonorrhoeae covered by the cobas® 4800 CT/NG Test’s primers and/or probes may result in failure to detect the presence of the bacterium.
• The presence of PCR inhibitors may cause false negative or invalid results.