Sexually Transmitted Infections

Diagnosis

Indications for Testing

  • Cervicitis, urethritis, pelvic inflammatory disease, amongst others

Laboratory Testing

  • CDC - testing recommendations
  • STI testing methods
    • Nucleic acid amplification testing (NAAT)
      • Preferred for detecting C. trachomatis and N. gonorrhoeae in a variety of specimens
      • Highly sensitive and specific
    • Culture
      • C. trachomatis
        • Not recommended for routine detection
        • May be considered for anatomic locations for which amplified testing has not been validated
        • May be used in medicolegal settings and to assess suspected treatment failure
        • High specificity; less sensitive than NAAT
      • N. gonorrhoeae
        • Not preferred testing – NAAT preferred for sensitivity and specificity
        • Recommended in combination with antimicrobial susceptibility testing in cases of suspected or documented treatment failure
        • May be considered if NAAT has not been validated for particular specimen type
        • Sensitivity dependent on transport time
          • N. gonorrhoeae is fastidious; viability declines rapidly during transport
    • DNA probes
      • NAAT testing preferred
    • DFA
      • Not recommended for detecting C. trachomatis
      • Relatively low sensitivity compared to NAAT
  • Refer to the following ARUP Consult topics for further STI testing recommendations

Differential Diagnosis

Screening

  • STI screening recommendations for women
    • STI screening recommendations for sexually active nonpregnant women

      STI Screening Recommendations for Sexually Active Nonpregnant Women

      STI

      USPSTF

      CDC

      AAFP

      ACOG

      Chlamydia

      Yearly screening – screen women <25 years and others at increased risk*

      Do not screen women >25 years and not at high risk

      Screen women ≤25 years and others at increased risk***

      Screen women ≤25 years and others at increased risk*

      Screen women ≤25 years and others at increased risk****

      Gonorrhea

      Screen women <25 years and others at increased risk*

      No recommendation for or against screening women not at risk and >25 years

      Screen women at increased risk***

      Do not screen general population

      Screen women <25 years and others at increased risk*

      Screen adolescents and others at increased risk****

      Syphilis

      Screen women at increased risk**

      Screen women exposed to syphilis

      Screen women at increased risk*

      Screen women at increased risk****

      HIV

      Screen women at increased risk*

      Screen all patients 13-64 years regardless of risk factors

      Screen women at increased risk*

      Screen women at increased risk****

      Hepatitis B

      Do not screen general population

      Provide prevaccination screening for women at increased risk***

      Do not screen general population

      No specific recommendation

      Hepatitis C

      Do not screen general population; insufficient evidence to recommend for or against screening women at increased risk

      Screen women at increased risk***

      Do not screen general population

      Do not screen general population; insufficient evidence to recommend for or against screening women at increased risk*

      Screen women at increased risk****

      HSV

      Do not screen asymptomatic patients

      Do not screen general population

      Do not screen general population

      Screen if sexual partner has HSV

      HPV

      Insufficient evidence to use as primary screening test for cervical cancer

      Do not screen for subclinical infection

      Insufficient evidence to use as primary screening test for cervical cancer

      Testing with a Pap smear is an option for women >30 years

      Bacterial vaginosisDo not screenNo recommendationNo specific recommendationsNo specific recommendations

      STI = sexually transmitted infection; USPSTF = U.S. Preventive Services Task Force; CDC = Centers for Disease Control and Prevention; AAFP = American Academy of Family Physicians; ACOG = American Congress of Obstetricians and Gynecologists; HIV = human immunodeficiency virus; HSV = herpes simplex virus; HPV = human papillomavirus; Pap = Papanicolaou

      * At risk = new or multiple partners; diagnosis of gonorrhea or chlamydia within the last 12 months; those not consistently using barrier methods; those having sex under the influence of drugs

      ** Commercial sex workers; persons who exchange sex for drugs; incarceration in adult correctional facility; multiple sex partners

      *** Increased risk defined as <25 years with inconsistent condom use; history of other STIs; multiple sex partners or drug use

      **** High-risk factors = history of multiple sexual partners or a sexual partner with multiple contacts; sexual contact with individuals with a culture-proven STI; history of repeated episodes of STIs; attendance at clinics for STIs

    • STI screening recommendations for pregnant women

      STI Screening Recommendations for Pregnant Women

      STI

      USPSTF

      CDC

      AAFP

      ACOG

      Chlamydia

      Screen women <25 years and others at increased risk*

      Screen all sexually active females ≤25 years and those >25 who are at risk**

      Screen women ≤25 years and others at increased risk*

      Screen women at increased risk***

      Gonorrhea

      Screen women <25 years and others at increased risk*

      Screen women at increased risk**

      Screen women at increased risk*

      Screen women at increased risk***

      Syphilis

      Screen all

      Screen all

      Screen all

      Screen all

      HIV

      Screen all

      Screen all

      Screen all

      Screen all

      Hepatitis B

      Screen all

      Screen all

      Screen all

      Screen all

      Hepatitis C

      No specific recommendation

      Screen women at increased risk**

      No specific recommendation

      Screen women at increased risk***

      HSV

      Do not screen asymptomatic patients

      No specific recommendation

      Do not screen general population

      No specific recommendation

      HPV

      No specific recommendation

      No specific recommendation

      No specific recommendation

      No specific recommendation

      Bacterial vaginosisDo not screen for low-risk patients; insufficient evidence to recommend screening in patients at high risk for preterm deliveryNo specific recommendationDo not screen for low-risk patients; insufficient evidence to recommend screening in patients at high risk for preterm deliveryNo specific recommendation

      STI = sexually transmitted infection; USPSTF = U.S. Preventive Services Task Force; CDC = Centers for Disease Control and Prevention; AAFP = American Academy of Family Physicians; ACOG = American Congress of Obstetricians and Gynecologists; HIV = human immunodeficiency virus; HSV = herpes simplex virus; HPV = human papillomavirus; Pap = Papanicolaou

      * At risk = new or multiple partners; diagnosis of gonorrhea or chlamydia within the last 12 months; those not consistently using barrier methods; those having sex under the influence of drugs

      ** Increased risk = defined as <25 years with inconsistent condom use; history of other STIs; multiple sex partners or drug use

      *** High-risk factors = history of multiple sexual partners or a sexual partner with multiple contacts; sexual contact with individuals with a culture-proven STI; history of repeated episodes of STIs; attendance at clinics for STIs

  • STI screening recommendations for men
    • USPSTF
      • No screening if not engaging in high-risk behaviors
      • If engaging in high-risk behaviors, screen for syphilis and HIV
    • CDC
      • Screen all men for HIV who seek medical care
      • Men who have sex with men are at risk – test for rectal and urethral gonorrhea and pharyngeal chlamydia annually

Clinical Background

Sexually-transmitted infections (STIs) constitute a major health burden in the U.S., and reported incidence among adolescents is increasing. These diseases are frequently asymptomatic and are most often caused by viruses or bacteria.

  • Most-common viral STIs
  • Most-common bacterial STIs
    • Chlamydia trachomatis

      Epidemiology

      • Incidence – 496.5/100,000 females (2008); most common reportable STI in U.S. and worldwide
      • Age – highest incidence is 15-25 years
      • Gram-negative obligate intracellular parasite

      Risk Factors

      • Multiple sex partners (≥2)
      • Non-Caucasian
      • Younger age (<25 years)
      • Coinfection with gonorrhea or HIV
      • Non-use of barrier methods
      • Previous history of STI

      Clinical Presentation

      • Asymptomatic in >50% of infected patients
      • Urethritis, salpingitis, epididymo-orchitis
      • Oropharyngeal disease
      • Pelvic inflammatory disease (PID)
      • Infection during pregnancy
        • Premature rupture of membranes
        • Preterm delivery
        • Low birth weight
        • Neonatal conjunctivitis
        • Neonatal pneumonia
      • Complications
        • Ectopic pregnancy
        • Tubal factor infertility
      Bacterial vaginosis (BV)

      Epidemiology

      • Prevalence – 16% of pregnant women; most common form of vaginitis (50% of women with BV are asymptomatic)
      • Caused by a combination of Gardnerella vaginalis with anaerobic bacteria overgrowth at the expense of commensal lactobacilli
        • Polymicrobial

      Risk Factors

      • Douching
      • Non-use of barrier methods
      • Multiple sex partners (>2)
      • Non-Caucasian

      Clinical Presentation

      • Malodorous vaginal discharge (fishy odor)
      • Vulvovaginitis, cervicitis, salpingitis
        • Infection during pregnancy
        • Increased risk of HIV infection
        • Preterm labor
        • Premature rupture of membranes
        • Postpartum endometriosis
      Neisseria gonorrhoeae

      Epidemiology

      • Incidence – 118.9/100,000 in 2007 (U.S.)
      • Age – highest incidence is 15-25 years
      • Nonmotile gram-negative diplococcus

      Risk Factors

      • Multiple sex partners (>2)
      • Non-Caucasian
      • Younger age (<25)
      • Coinfection with HIV
      • Non-use of barrier methods
      • Previous history of STI
      • Douching

      Clinical Presentation

      • Cervicitis, urethritis, salpingitis
      • PID
      • Oropharyngeal disease
      • Neonatal infection
    • Treponema pallidum (syphilis)
  • Most-common parasitic/protozoan STI
    • Trichomonas vaginalis

      Epidemiology

      • Prevalence – 7 million cases annually in U.S.
      • Age – highest incidence is 30-50 years 
      • Flagellated protozoan

      Risk Factors

      • Multiple sex partners (>2)
      • Non-Caucasian
      • Coinfection with gonorrhea or HIV
      • Non-use of barrier methods
      • Previous history of STI
      • Infected with HIV

      Clinical Presentation

      • Up to 50% of women with T. vaginalis infections have minimal or no symptoms
        • If symptomatic, T. vaginalis infections can cause vaginitis, urethritis, and cervicitis
      • May present with vaginal, malodorous discharge, strawberry cervix, dysuria, and vulvar irritation (accounts for 15-20% of cases of vulvovaginitis)
      • Pregnant females
        • Increased risk of HIV transmission
        • Preterm labor
        • Premature rupture of membranes
        • Low birth weight

Treatment

Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
Sexually Transmitted Disease Panel 1 by Transcription-Mediated Amplification 2006258
Method: Qualitative Transcription-Mediated Amplification

Preferred test for detecting C. trachomatis, N .gonorrhoeae, and T. vaginalis in variety of specimens

Refer to Sample Collection for the Diagnosis of STD Using Nucleic Acid Amplification Tests for optimal specimen types and collection instructions

Highly sensitive and specific

Testing of oral and rectal specimens is not recommended

The performance of this test has not been evaluated in adolescents <14 years

 
Chlamydia trachomatis and Neisseria gonorrhoeae by Transcription-Mediated Amplification (TMA) 0060241
Method: Qualitative Transcription-Mediated Amplification

Preferred test for detecting C. trachomatis and N. gonorrhoeae in variety of specimens

Positive results are confirmed using an alternative nucleic acid target in according with CDC guidelines

Refer to Sample Collection for the Diagnosis of STD Using Nucleic Acid Amplification Tests for optimal specimen types and collection instructions

Highly sensitive and specific

Culture may be required in certain clinical contexts for diagnosing C. trachomatis and N. gonorrhoeae infections to meet applicable laws and regulations

 
Chlamydia trachomatis and Neisseria gonorrhoeae by Transcription-Mediated Amplification (TMA), ThinPrep 0060734
Method: Transcription-Mediated Amplification

Can be used to detect C. trachomatis and N. gonorrhoeae in ThinPrep specimens

For optimal sensitivity, vaginal swabs are recommended

Positive results are confirmed using an alternative nucleic acid target in according with CDC guidelines

Refer to Sample Collection for the Diagnosis of STD Using Nucleic Acid Amplification Tests for optimal specimen types and collection instructions

Culture may be required in certain clinical contexts for diagnosing C. trachomatis and N. gonorrhoeae infections to meet applicable laws and regulations

The performance of this test has not been evaluated in adolescents <16 years

 
Chlamydia trachomatis and Neisseria gonorrhoeae by Transcription-Mediated Amplification (TMA), SurePath 2001551
Method: Transcription-Mediated Amplification

Can be used to detect C. trachomatis and N. gonorrhoeae in SurePath specimens

For optimal sensitivity, vaginal swabs collected and transported using the manufacturers’ collection kits are recommended

Positive results are confirmed using an alternative nucleic acid target in accordance with CDC guidelines

Refer to Sample Collection for the Diagnosis of STD Using Nucleic Acid Amplification Tests for optimal specimen types and collection instructions

Use of transport media other than the manufacturer's collection kit may result in reduced sensitivity

Culture may be required in certain clinical contexts for diagnosing C. trachomatis and N. gonorrhoeae infections to meet applicable laws and regulations

The performance of this test has not been evaluated in adolescents <16 years

 
Trichomonas vaginalis by Transcription-Mediated Amplification (TMA) 2005506
Method: Qualitative Transcription-Mediated Amplification

Diagnose infection with T. vaginalis from genitourinary sources

Refer to Sample Collection for the Diagnosis of STD Using Nucleic Acid Amplification Tests for optimal specimen types and collection instructions

Performance of test on self-collected vaginal swab specimens and those from pregnant women has not been evaluated

The performance of this test has not been evaluated in adolescents <14 years

 
Chlamydia trachomatis by Transcription-Mediated Amplification (TMA) 0060243
Method: Qualitative Transcription-Mediated Amplification

Use to detect C. trachomatis; in individuals at risk for N. gonorrhoeae, preferred test is one of the combined nucleic acid amplification tests (NAAT)

Highly sensitive and specific

Positive results are confirmed using an alternative nucleic acid target in according with CDC guidelines

Refer to Sample Collection for the Diagnosis of STD Using Nucleic Acid Amplification Tests for optimal specimen types and collection instructions

Culture may be required in certain clinical contexts for diagnosing C. trachomatis and N. gonorrhoeae infections to meet applicable laws and regulations  
Neisseria gonorrhoeae by Transcription-Mediated Amplification (TMA) 0060244
Method: Qualitative Transcription-mediated Amplification

Use to detect N. gonorrhoeae

 Preferred test is one of the combined nucleic acid amplification tests (NAAT)

Highly sensitive and specific

Positive results are confirmed using an alternative nucleic acid target in according with CDC guidelines

Refer to Sample Collection for the Diagnosis of STD Using Nucleic Acid Amplification Tests for optimal specimen types and collection instructions

Culture may be required in certain clinical contexts for diagnosing C. trachomatis and N. gonorrhoeae infections to meet applicable laws and regulations or for use in suspected failure of therapy  
Chlamydia trachomatis Culture 0060850
Method: Cell Culture/Immunofluorescence

Not recommended for routine detection of C.  trachomatis

Use to detect C.  trachomatis in medicolegal settings and to assess suspected treatment failure

May be considered for anatomic locations for which amplified testing has not been validated

High specificity

Diagnose infection with C. trachomatis

Culture should be ordered in cases of suspected sexual abuse or suspected failure of therapy

Historically the gold standard for diagnosis

Less sensitive than nucleic acid amplification tests

Two to three days required for results

Amplified DNA testing is recommended for detection of C. trachomatis from endocervical or urethral specimens; refer to C. trachomatis by Amplified Detection (APTIMA)

Culture may be required in certain clinical contexts for diagnosing C. trachomatis and N. gonorrhoeae infections to meet applicable laws and regulations

 
Gonorrhea Culture 0060110
Method: Culture/Identification

May be used to detect N. gonorrhoeae, especially if NAAT has not been validated for a particular specimen type

Preferred test to diagnose N. gonorrhoeae is one of the combined nucleic acid amplification tests (NAAT)

Sensitivity is dependent on transport time; N. gonorrhoeae is fastidious, and viability declines rapidly during transport

 
Additional Tests Available
 
Click the plus sign to expand the table of additional tests.
Test Name and NumberComments
Ureaplasma Species and Mycoplasma hominis Culture 0065031
Method: Culture

Use to detect Mycoplasma hominis and Ureaplasma spp

Use if clinical suspicion exists and all other testing is negative

Other than lung transplant specimens, this test is not appropriate for adult respiratory specimens

Vaginal Pathogen Panel by DNA Probe 0065153
Method: Qualitative Nucleic Acid Probe

Use to detect common vaginal pathogens associated with vaginitis/vaginosis

For T. vaginalis, preferred test is one of the nucleic acid amplification tests (NAAT)

Not recommended as stand-alone test for sexually transmitted infection testing or screening

Chlamydia trachomatis and Neisseria gonorrhoeae by Transcription-Mediated Amplification (TMA), M4/UTM 0060774
Method: Transcription-Mediated Amplification

Viral transport media (eg, M4/UTM) are not preferred for C. trachomatis and N. gonorrhoeae by Amplified Detection (APTIMA)

Refer to Sample Collection for the Diagnosis of STD Using Nucleic Acid Amplification Tests for optimal specimen types and collection instructions

Neisseria gonorrhoea Antibodies, Total 0099685
Method: Semi-Quantitative Complement Fixation

Not recommended 

Less sensitive than amplification-based methods

Chlamydia Antibody Panel, IgG & IgM by IFA 0065100
Method: Semi-Quantitative Indirect Fluorescent Antibody

Limited value in the diagnosis of most oculogenital (eg, eyes, genitalia) chlamydial infections

Chlamydia Antibody Panel, IgM by IFA 0065105
Method: Semi-Quantitative Indirect Fluorescent Antibody

Limited value in the diagnosis of most oculogenital (eg, eyes, genitalia) chlamydial infections

Chlamydia Antibody Panel, IgG by IFA 0065139
Method: Semi-Quantitative Indirect Fluorescent Antibody

Limited value in the diagnosis of most oculogenital (eg, eyes, genitalia) chlamydial infections