Gonorrhea laboratory tests

Sexually transmitted diseases Main Page
Gonorrhea Microchapters
Home
Patient Info
Overview
Historical perspective
Classification
Pathophysiology
Causes
Differentiating Gonorrhea from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications, and Prognosis
Diagnosis
History and Symptoms
Physical Examination
Laboratory Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Antibiotic Resistance
Primary Prevention
Secondary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Gonorrhea laboratory tests On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Gonorrhea laboratory tests All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Gonorrhea laboratory tests
CDC on Gonorrhea laboratory tests
Gonorrhea laboratory tests in the news
Blogs on Gonorrhea laboratory tests
Directions to Hospitals Treating Gonorrhea
Risk calculators and risk factors for Gonorrhea laboratory tests

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]

Overview

Empiric treatment for gonorrhea usually is initiated prior to the laboratory result. A microbiologic diagnosis is important for further management in order to determining the need for test of cure, partner management, and public health reasons. Any sexually active man or women presenting with signs and symptoms of urethritis, cervicitis, pelvic inflammatory disease, and epididymitis should undergo diagnostic testing for Neisseria gonorrhea. Additionally, disseminated gonococcal infection (DGI) should be consider in all young sexually active individuals who present with arthralgias or suspected septic arthritis. Common laboratory tests for gonococcal infection may include Gram Stain, culture, nucleic acid amplification tests (NAATs), and Non-amplified tests. Nucleic acid amplification tests (NAATs) is test of choice in all individuals who present with urogenital symptoms.

Laboratory tests

Several laboratory tests are available to diagnose gonorrhea. A doctor or nurse can obtain a sample for testing from the parts of the body likely to be infected (cervix, urethra, rectum, or throat) and send the sample to a laboratory for analysis. Gonorrhea that is present in the cervix or urethra can be diagnosed in a laboratory by testing a urine sample.

Diagnostic Techniques

Gram stain

• Gram stain of urethral discharge is highly sensitive and specific in men with symptomatic urethritis
• Gram stain of endocervical, pharyngeal, and rectal specimens is insufficient and is not recommended
• In symptomatic men, polymorphonuclear leukocytes (PMNs) with intracellular gram-negative diplococci can be considered diagnostic for infection with Neisseria gonorrhea.
• Common anatomic sites for taking samples include:
  • urethral discharge in men
  • Synovial fluid
  • Cervical in women

• 

  Neisseria gonorrhoeae in cervical smear using the Gram-stain

• 

  Urethral discharge for Neisseria gonorrhea revealed Gram-negative intracellular rods

• 

  Intracellular Gram-negative diplococcal

Cultures

Culture (Thayer-Martin medium) is the historical standard for detection of Neisseria gonorrhea.

• Culture test advantages over non-culture tests include:
  • Low cost
  • Suitable for a variety of specimen sites
  • Antimicrobial susceptibility testing can be performed
• Common anatomic sites for taking samples include:
  • Vaginal and cervical
  • Urethral discharge in men
  • pharyngeal
  • Rectal
  • Synovial fluid
  • Blood cultures

Nucleic Acid Amplification Tests (NAATs)

Gold standard for diagnosing gonococcal infections.

Amplified tests include:

• Polymerase chain reaction (PCR)
• Transcription-mediated amplification (TMA)
• Strand displacement amplification (SDA)

NAAT is FDA-cleared for:

• Endocervical swabs from women
• Urethral swabs from men
• Urine specimens from both males and females
• Vaginal swabs

NAAT is not FDA-cleared for detection of rectal, oropharyngeal, and conjunctival gonococcal infection.

• There is a concern about cross-reactivity with other Neisseria species when used at the oropharyngeal site.

• Some laboratories have met CLIA regulatory requirements and established performance specifications for using NAAT with rectal and oropharyngeal swab specimens that can inform clinical management.
• Antimicrobial susceptibility cannot be determined with these tests. However, the same specimen can be evaluated for Chlamydia trachomatis.

Non-amplified tests

Non-amplified tests used for Neisseria gonorrhea include:

• DNA probe (e.g., Gen-Probe PACE 2 and Digene Hybrid Capture II)

Antimicrobial susceptibility cannot be determined with these tests. However, the same specimen can be evaluated for Chlamydia trachomatis.

Non disseminated gonococcal infection

Empiric treatment for gonorrhea usually is initiated prior to the laboratory result. However, a microbiologic diagnosis is important for further management in order to determining the need for test of cure, partner management, and public health reasons. Any sexually active man or women presenting with signs and symptoms of urethritis, cervicitis, pelvic inflammatory disease, and epididymitis should undergo diagnostic testing for Neisseria gonorrhea.

Men with urogenital presentation

• Urethral swabs or first-catch urine (20 to 30 mL of the initial urinary stream) specimens for NAAT is test of choice
• Positive Gram stain of urethral swab is also sufficient and NAAT is not need to be done
• Urethral swab specimens for Gram stain, culture, antigen detection, and genetic probe methods are also acceptable (if NAAT are unavailable)

Women with urogenital presentation

• Vaginal swab or endocervical swab specimens for NAAT is test of choice
• Urine and liquid Pap smear specimens for NAAT is also acceptable
• Endocervical swabs specimens for Gram stain, culture, antigen detection, and genetic probe method are also acceptable (if NAAT are unavailable)

Men an women with extragenital presentation

• Rectal and pharyngeal swabs for NAAT is the preferred diagnostic test for these sites
• Rectal and pharyngeal swabs for culture can also be used

Disseminated gonococcal infection

In general, disseminated gonococcal infection (DGI) should be consider in all young sexually active individuals (young women and all men who have sex with men) who present with arthralgias or joint pain or suspected septic arthritis. Laboratory findings for disseminated gonococcal infection (DGI) may include the following:

Blood Culture

• Blood cultures are diagnostic and more likely to be positive in patients with arthritis-dermatitis syndrome (two sets of blood cultures need to be taken)
• Blood cultures are helpful in differentiating DGI from other conditions such as septic arthritis due to Neisseria meningitidis or Staphylococcus aureus

Synovial fluid

• Synovial fluid analysis is usually sent for cell count, differential, Gram stain, bacterial culture and NAAT in patients with suspected DGI
• Synovial fluid cultures are positive for Neisseria gonorrhoeae in approximately 50% patients with purulant arthritis
• Synovial fluid cultures are less likely to be positive in patients with arthritis-dermatitis syndrome
• Synovial fluid leukocyte count in gonococcal arthritis is approximately range from 10,000 cells/mm to 50,000 cells/mm3.
• Synovial fluid glucose, lactate dehydrogenase, or protein in gonococcal arthritis have only limited value

Mucosal sites specimens

• Urogenital, rectal, and pharyngeal specimens should be sent for culture and NAAT in all patients with suspected DGI.
• Positive urogenital, rectal, or pharyngeal infection are generally seen in patients with DGI. However, most patients with DGI are asymptomatic at these sites.

Skin lesion specimens

• In the pustular skin lesions, the specimens can be sent for Gram stain, culture and NAAT
• NAAT and cultures are not routinely done in patients with suspected DGI

References

Template:WH Template:WS