Lab Test

Chlamydia trachomatis and Neisseria gonorrhoeae Detection by Nucleic Acid Amplification

CT, NAAT, NG, GC, STI, STD

Test Codes

EPIC: LAB6531, Code: ICNG

Department

Molecular Pathology

Instructions

Nucleic Acid Amplification testing (NAAT) is the preferred option for the detection of Chlamydia trachomatis (Ct) and Neisseria gonorrhoeae (Ng). Swabs (urethral, endocervical), urine, and ThinPrep® PreservCyt liquid-based cytology specimens are acceptable for testing. ThinPrep® PreservCyt specimens offer the patient and physician an efficient means to perform Ct and Ng testing in conjunction with routine cytology and HPV testing as clinically indicated.

Dearborn, Taylor, Trenton, Wayne:
Beaumont Laboratory will now test throat and rectum sources for Chlamydia and Neisseria gonorrhoeae at Dearborn Laboratory using Cepheid Xpert technology. This will allow a highly sensitive and specific Nucleic Acid Amplification method to be performed on one sample (per source) with a faster turn-around time. Collection devices will change to the Xpert Swab Specimen Collection Kit for these sources only.

Specimen Collection Criteria

Collect: Swab, urine, or ThinPrep® PreservCyt specimen, as described below:

SWABS:

Female Endocervical:

  • Preferred specimen: Roche Cobas® PCR Female Swab Specimen Collection Kit.
  • Also acceptable: Swab specimen in UVT or UTM Transport Medium.

Dearborn, Taylor, Trenton, Wayne:

  • Throat or Rectum sources use Xpert Swab Specimen Collection Kit.

URINE (Male or Female):  

Preferred specimen: First void clean catch urine in Roche Cobas® PCR Urine Specimen Collection kit. 

Also acceptable:

  • First void clean catch urine in a sterile collection container or yellow top urine tube. (Minimum: 5.0 mL)
  • Midstream urine in a sterile container or yellow top urine tube. Midstream specimens have decreased clinical sensitivity and are of limited diagnostic value. (Minimum: 5.0 mL)

Chlamydia trachomatis and Neisseria gonorrhoeae tests MUST be ordered at the time of collection.

Add-on tests CANNOT be performed on urine specimens following testing on the Urinalysis Instrument.

ThinPrep® PRESERVCYT LIQUID BASED CYTOLOGY (Female endocervical):
  • Chlamydia trachomatis and Neisseria gonorrhoeae tests MUST be ordered at the time of collection.
  • Add-on tests CANNOT be performed once the ThinPrep® specimen has been processed for cytology and/or HPV testing.
  • Chlamydia trachomatis and Neisseria gonorrhoeae test results WILL be reported separately, and NOT as a component of the combined PAP/HPV report. 

Physician Office/Draw Specimen Preparation

Maintain swab and ThinPrep® specimens at room temperature (20-26°C or 68-78.8°F) prior to transport. Urine specimens must be refrigerated (2-8°C or 36-46°F) if not to be received in the Laboratory within 8 hours of collection.

Preparation for Courier Transport

Transport: All specimen types, refrigerated (2-8°C or 36-46°F).

Rejection Criteria

  • Unlabeled specimens.
  • Specimens submitted in transport media other than those listed.
  • SurePath liquid-based cytology specimens.
  • Non-genitourinary specimens require approval from the Medical Director or Supervisor. 
  • Add-on requests for samples that have been previously run on other instrumentation.

Inpatient Specimen Preparation

Specimens should be sent to the main Laboratory if received at Royal Oak. Specimens received at Farmington Hills should be sent to microbiology.

Storage

Specimen Stability for Testing:

Roche Cobas® PCR Female Swab
Room Temperature (20-26°C or 68-78.8°F): 365 days
Refrigerated (2-8°C or 36-46°F): 365 days
Frozen (-20°C/-4°F or below): Unacceptable

Swab Specimens in UVT or UTM Transport Medium
Room Temperature (20-26°C or 68-78.8°F): 2 days
Refrigerated (2-8°C or 36-46°F): 14 days
Frozen (-20°C/-4°F or below): 14 days

Roche Cobas® PCR Urine Tube
Room Temperature (20-26°C or 68-78.8°F): 365 days
Refrigerated (2-8°C or 36-46°F): 365 days
Frozen (-20°C/-4°F or below): Unacceptable

Neat Urine Specimens
Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 24 hours
Frozen (-20°C/-4°F or below): 180 days

ThinPrep® PreservCyt Specimens
Room Temperature (20-26°C or 68-78.8°F): 365 days
Refrigerated (2-8°C or 36-46°F): 365 days
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

UVT or UTM Transport Medium: Refrigerated (2-8°C or 36-46°F): 7 days

Roche Cobas® Swab or Urine Collection: Room Temperature (20-26°C or 68-78.8°F): 7 days

ThinPrep® PreservCyt Specimens Room Temperature (20-26°C or 68-78.8°F): 6 weeks

Laboratory

Royal Oak Clinical Molecular Pathology Laboratory
Dearborn Molecular Pathology Laboratory
Taylor Molecular Pathology Laboratory
Trenton Molecular Pathology Laboratory
Wayne Molecular Pathology Laboratory

Performed

Monday – Saturday.
Results are usually available within 24 hours of receipt in the Laboratory (excluding weekends and holidays).

Dearborn, Taylor, Trenton, Wayne:
Monday – Friday.

Reference Range

Negative for Chlamydia trachomatis.
Negative for Neisseria gonorrhoeae.

Test Methodology

Real-time PCR Amplification and Detection (RT-PCR) - Roche Cobas® 4800 System.

This test is FDA approved for diagnostic purposes.

Dearborn, Taylor, Trenton, Wayne:
Cepheid Gene Xpert NAAT.

Interpretation

By report.

Clinical Utility

The presence or absence of Chlamydia trachomatis or Neisseria gonorrhoeae can be assessed in genitourinary specimens using DNA-based nucleic acid amplification technology, which has been shown to be more sensitive than culture. This test may be used for diagnostic or screening purposes for symptomatic or asymptomatic patients.

Reference

  1. Centers for Disease Control and Prevention. Sexually Transmitted Diseases Treatment Guidelines, 2015. MMWR 2015 64(3):55-68.

CPT Codes

87491, 87591.

Contacts

Last Updated

10/3/2022

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