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Unit Code 110302:
Neisseria gonorrhoeae by Nucleic Acid Amplification (GEN-PROBE)

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Useful For

Diagnosing Neisseria gonorrhoeae infections

Clinical Information

Neisseria gonorrhoeae, a gram-negative bacterium, is a common

cause of sexually transmitted infection. This organism causes

dysuria and urethral discharge in males with acute urethritis;

complications may include pelvic inflammatory disease in women,

and ascending infection resulting in gonococcal epididymitis and

prostatitis in men.

 

Neisseria gonorrhoeae is labile and does not remain viable for

sustained periods of time. Diagnosis by culture methods, rather

than NAT testing, especially after extended transit times, is not

recommended. Previously, culture was considered the gold

standard test for diagnosis of Neisseria gonorrhoeae infections.

However, the organisms are labile in vitro, and precise specimen

collection, transportation, and processing conditions are required

to maintain organism viability, a necessity for culturing. Nucleic

acid amplification testing (NAAT), which detects DNA of the organism,

does not require the organism to be alive, is much more sensitive than

culture, and is now considered the preferred test for detecting

Neisseria gonorrhoeae.

 

Improved screening rates and increased sensitivity of NAAT testing

translate to increased numbers of accurately diagnosed cases.

Improved detection rates resulting from both increased assay

performance and patients' easy acceptance of urine testing,

combined with appropriate treatment, decrease disease burden

and spread.(3-5) Early identification of infection enables sexual

partners to seek testing and/or treatment as soon as possible

and reduces the risk of disease spread. Prompt treatment reduces

the risk of infertility in women.

Reference Values

Negative

Interpretation

A positive result indicates the presence of rRNA of Neisseria

gonorrhoeae.

 

A negative result indicates that rRNA for Neisseria gonorrhoeae

was not detected in the specimen.

 

The predictive value of an assay depends on the prevalence of

the disease in any particular population. In settings with a high

prevalence of sexually transmitted disease, positive assay results

have a high likelihood of being true positives. In settings with a low

prevalence of sexually transmitted disease, or in any settings in

which a patient's clinical signs and symptoms or risk factors are

inconsistent with gonococcal or chlamydial urogenital infection,

positive results should be carefully assessed and the patient

retested by other methods (eg, culture for Neisseria gonorrhoeae),

if appropriate.

Cautions

This report is intended for use in clinical monitoring or management

of patients; it is not intended for use in medico-legal applications.

 

Appropriate specimen collection and handling is necessary for

optimal assay performance.

 

Results should be interpreted in conjunction with other laboratory

and clinical information.

 

A negative test result does not exclude the possibility of infection.

Improper specimen collection, concurrent antibiotic therapy,

presence of inhibitors, or low numbers of organisms in the

specimen (ie, below the sensitivity of the test) may cause

false-negative test results.

 

In low prevalence populations, positive results must be interpreted

carefully as false-positive results may occur more frequently than

true positive results in this setting.

 

This assay cannot be used to assess therapeutic success or failure,

since nucleic acids from the organism may persist following

antimicrobial therapy.

 

The presence of mucous does not interfere with this assay. However,

this test requires endocervical cells, and if excess mucous is not

removed prior to collection, adequate numbers of these cells may

not be obtained.

 

No interference is expected due to:

 - Blood (urine and swabs) specimens

 - Lubricants and spermicides (swabs)

 

The effects of use of tampons, douching, specimen types other than

those listed in "Specimen Required,” and specimen collection variables

have not been determined.

 

Testing of urine specimens with this method is not intended to replace

cervical exam and endocervical sampling for diagnosis of urogenital

infection; infections may result from other causes or concurrent infections

may occur.

 

Testing urine specimens as the sole test for identifying female patients

with gonococcal infections may miss some infected individuals.

 

Performance estimates for urine specimens are based on evaluation of

urine obtained from the first part of the urine stream; performance on

midstream collections has not been determined.

Clinical Reference

1.   Centers for Disease Control and Prevention. 2002. Reporting

      of laboratory-confirmed chlamydial infection and gonorrhea

      by providers affiliated with three large Managed Care

      Organizations - United States,1995-1999. MMWR Morb Mortal

      Wkly Rep 2002;51:256-259

 

2.   Centers for Disease Control and Prevention:  Screening Tests

      To Detect Chlamydia trachomatis and Neisseria gonorrhoeae

      Infections-2002. Morbidity and Mortality Weekly Report

      Recommendations and Reports October 18, 2002;Vol. 51;

      No RR-15

 

3.   Crotchfelt KA, Pare B, Gaydos C, Quinn TC:  Detection of Chlamydia

      trachomatis by the GEN-PROBE AMPLIFIED Chlamydia trachomatis

      Assay (AMP CT) in urine specimens from men and women and

      endocervical specimens from women. J Clin Microbiol. 1998

      Feb;36(2):391-394

 

4.   Gaydos CA, Quinn TC, Willis D, et al:  Performance of the APTIMA

      Combo 2 assay for detection of Chlamydia trachomatis and

      Neisseria gonorrhoeae in female urine and endocervical swab

      specimens. J Clin Microbiol. 2003 Jan;41(1):304-309

 

5.   Chernesky MA, Jang DE:  APTIMA transcription-mediated

      amplification assays for Chlamydia trachomatis and Neisseria

      gonorrhoeae. Expert Rev Mol Diagn 2006 Jul;6(4):519-525

Key