Synonym

• GenProbe

Tubes

The specimens collected are:

• Sample is collected from the affected site with a sterile swab and placed in a suitable transport container (2SP transport medium provided by lab)
• Urethra in men and women
• Endocervix in women
• Vaginal in prepubertal girls
• Rectum
• Throat
• Eye
• Nasopharynx in infants
• Aspirate of bubo
• Blood
• Red or tiger top tube
• 7 mL of venous blood
• Urine in a sterile container (provided by lab)

Additional information:

• Endocervical specimen: Use one swab to remove exudate or mucus from endocervix and discard. Insert second swab or cytobrush until its tip is no longer visible, then rotate the swab for 5-10 seconds or brush the endocervix gently and withdraw it without touching the vaginal walls. Place the second swab or cytobrush in the transport container
• Urethral specimen in men: Remove pus or exudate from the site with one swab and discard. Insert a second small swab with a wire shaft 2-4 cm into the penis, gently rotate the swab to dislodge cells, and then withdraw the swab. Place swab into transport container
• Rectal specimen: Use one swab to remove any contamination by stool from anus. Insert a second swab into anal canal about 2.5 cm, move swab from side to side, and leave it in place for several seconds for optimum absorption, and then withdraw the swab. Place swab into transport container
• Throat specimen: Depress tongue and expose pharynx. Swab posterior pharynx, tonsils, and tonsillar fossae without touching teeth, cheeks, or tongue. Place swab into transport container
• Eye sample: Gently brush the insides of lower and upper eyelids of the client with a swab and place in a suitable container
• Urine sample: The client is instructed to collect the first part of urine stream, immediately at the beginning of urination in a sterile container (first catch urine)
• Instruct female client not to douche for 24 hrs before test
• Instruct male client not to void urine for 3 hours preceding test
• The specimens for culture should be refrigerated at 2-8ºC if processed within <24 hours after collection. If delayed, freeze at -70ºC in transport media, so that the viability remains for 2 years. Avoid storage at -20ºC or in frost-free freezers
• The swab specimen collected for NAAT and DNA probe test should be processed within 7 days if refrigerated at 2-8ºC or upto 60 days if frozen at -70ºC
• The swab specimen collected for DFA test is rolled over a slide, which is then dried and fixed. It is checked within 7 days if kept at ambient temperature or fixed and unstained slides can be stored at -20ºC for 2 years
• The specimen collected for EIA should be processed within 24 hrs if kept at room temperature or within 5 days if stored at 2-8ºC. Do not freeze the sample
• Handle blood sample gently to prevent hemolysis
• Send specimens to lab immediately

Info

• Chlamydia testing involves a group of tests to detect the presence of C.trachomatis bacteria, its antigen, or antibodies from the sample collected
• Chlamydia is one of the most common sexually transmitted diseases (STDs), and is caused by Chlamydia trachomatis a gram-negative intracellular bacteria
• C.trachomatis has 18 serologically variant strains, which include:
• Immunotypes A, B, Ba, and C cause trachoma (chronic conjunctivitis endemic in Africa and Asia)
• Immunotypes D-K cause genital tract infections
• Immunotypes L1-L3 cause lymphogranuloma venereum
• The group of tests to detect chlamydia infection include:
• Chlamydia culture
• Direct fluorescent antibody test (DFA)
• Enzyme-linked immunosorbent assay (ELISA, EIA)
• Nucleic acid amplification tests (NAAT)
• Nucleic acid hybridization test (DNA probe test, molecular probe test)
• Serologic tests
• Giemsa staining
• Leukocyte esterase test (LE)

Clinical

• The clinical utility of chlamydia testing include:
• To confirm chlamydia infection in persons presenting with signs and symptoms of an STD
• To screen women who have the following risk factors for chlamydia:
• High risk sexual behavior or multiple sex partners
• Attendance in adolescent care, STD, prenatal, or family planning clinics
• Undergoing elective abortion
• Residing in detention facilities
• Presence of mucopurulent cervicitis
• Screening during pregnancy
• Infants born to mothers infected with chlamydia during delivery
• Differential diagnosis with other STDs such as:
• Gonorrhea
• Syphilis
• Herpes
• Hepatitis B
• HIV
• Chlamydia is transmitted primarily through sexual contact with an infected partner and from mother to newborn during delivery (vertical transmission)
• Around 75% of women and 50% of men infected with chlamydia are asymptomatic, thus Chlamydia is known as the "Silent Epidemic" as it may not cause any symptom and will linger for months or years before being detected
• Chlamydia may clinically manifest as:
• Women
• Painful/burning sensation or frequent urination
• Abnormal vaginal discharge
• Abnormal vaginal bleeding during or after sex or between periods
• Genital itching
• Irregular menstrual bleeding
• Lower abdominal pain
• Fever and general tiredness
• Anal itching, pain, bleeding, or discharge
• Sore throat (rare)
• Men
• Painful/burning sensation or frequent urination
• Abnormal discharge from the penis, initially clear or milky, and then yellow, creamy, sometimes blood-tinged
• Sometimes scrotal pain and swelling
• Perineal fullness
• Fever
• Anal itching, pain, bleeding, or discharge
• Sore throat (rare)
• Infants (usually before 3 months of age)
• Afebrile illness
• Progressive tachypnea
• Rales
• Staccato cough
• Conjunctivitis
• The clinical spectrum of chalmydial infection and its complications include:
• In women
• Nongonococcal urethritis (NGU)
• Lymphogranuloma venereum (LGV)
• Subclinical genital infections
• Arthritis
• Conjunctivitis
• Cyst and abscess formation in ovaries
• Ectopic pregnancy
• Fitz-Hugh-Curtis syndrome (rare)
• Infertility
• Pelvic inflammatory disease (PID)
• Pneumonia
• Reiter's syndrome
• Trachoma
• In men
• Nongonococcal urethritis (NGU)
• Lymphogranuloma venereum (LGV)
• Subclinical genital infections
• Arthritis
• Conjunctivitis
• Epididymitis
• Infertility
• Pneumonia
• Proctitis (in homosexual men)
• Prostatitis
• Reiter's syndrome
• Trachoma
• In pregnant women
• Spontaneous abortion
• Preterm labor
• Premature rupture of membranes
• Premature delivery
• Small for gestational age or low birth weight infants
• Postpartum PID
• About 50-75% infants born to infected mothers during delivery develop:
• Opthalmia neonatorum (conjunctivitis) resulting in blindness (trachoma) in 20-50% of infants
• Nasopharyngeal infection
• Pneumonia in 30% of infants
• Lymphogranuloma venereum occurs in three stages:
• Primary stage
• It is a transient stage and may go undetected in many cases. It occurs after an incubation period of 3-21 days following an exposure
• The primary lesion is seen as painless papule, shallow ulcer or erosion, a small herpetiform lesion (most common), or non-specific urethritis
• Secondary stage
• Occurs after an incubation period of 10-30 days (rarely as long as 6 months)
• It is characterized by enlarged, tender regional lymph nodes (buboes) along with fever, headache, malaise, chills, nausea, vomiting, and arthralgias
• Inguinal lymphadenopathy occurs if the primary lesion involves the anterior vulva, penis, or urethra (the adenopathy is unilateral in 75% of cases)
• Perirectal and pelvic lymphadenopathy result if the primary lesion involves the posterior vulva, vagina, or anus
• Tertiary stage
• It is characterized by proctocolitis, clinically seen as pruritus, bloody mucopurulent rectal discharge, fever, rectal pain, tenesmus, constipation, pencil-thin stools, and weight loss
• Very late stages have fibrosis and granulomas seen in women as esthiomene (eating away), which results in hypertrophic, chronic granulomatous enlargement of the vulva and subsequent ulceration. Elephantiasis of genitalia is seen in men
• Trachoma
• Has an average incubation period of 5-12 days, begins slowly as conjunctivitis (pink eye) and if left untreated leads to scarring, resulting in eye ulcers, further scarring, vision loss, and blindness
• WHO has a simplified trachoma grading scheme clinically, which is as follows:
• Follicular trachoma (TF)
• Intense inflammatory trachoma (TI)
• Trachomatous scarring (TS)
• Trichiasis (TT)
• Corneal opacity (CO)

Additional information

• It is estimated that 3 million infections with chlamydia are detected annually in U.S alone (CDC) and 89 million cases are detected annually worldwide (WHO)
• Chlamydia is 5-6 times more common than gonorrheal infections
• Lab diagnosis of chlamydia infection include:
• Chlamydia culture:
• It is a standard test for medicolegal situations such as sexual assault and child abuse
• Specimen for culture collected are from urethra for women and asymptomatic men, nasopharyngeal specimens for infants, rectal specimens for all ages, and vaginal specimens for prepubetal girls
• Chlamydia infection is confirmed by the presence of cytoplasmic inclusion bodies from the cell culture
• It has a sensitivity of 60-80% and specificity of 100%
• The disadvantages with this test is that it needs special medium for transport and cell culture, to be stored at 4°C, and requires 3-7 days for results
• Direct fluorescent antibody test (DFA):
• It is an antigen detection test done primarily on endocervical specimens (sensitivity is 80-90% and specificity is 98-99%) and from conjunctival, urethral, rectal smears, and respiratory secretions in infants
• An average processing time is 30-40 minutes where the smear is then stained with a fluorescent-labeled monoclonal antibody (anti-MOMP) specific for C. trachomatis and examined by fluorescence microscopy
• An additional advantage is that the quality of the specimen can be assessed by checking for the presence of columnar epithelial cells
• The disadvantages are that the test is time consuming and requires a trained microscopist
• Enzyme-linked immunosorbent assay (EIA):
• The EIA test detects the antigen lipopolysaccharide (LPS) using an antibody labeled with an enzyme with a processing time of 3-4 hours
• The anti-LPS antibody can cross react with other microorganisms including other chlamydia species giving false positive results
• This test is not done on rectal specimens because of cross reaction with fecal bacteria
• The specificity of EIA is improved to >99% with the use of confirmatory blocking assay and sensitivity is 70-80%
• Nucleic acid amplification tests (NAAT):
• Specimens suitable for NAATs are endocervical in women, urethral in men and urine sample for both men and women
• Specimens collected from vagina, oropharyngeal and rectal sites are not recommended
• This test is based on amplification of nucleic acids specific to C. trachomatis by polymerase/ligase chain reaction (PCR/LCR), strand displacement amplification, and transcription-mediated amplification (TMA).
• The sensitivity is 90% and specificity is 99-100%
• The advantage being the ability to use as a screening test with the urine sample and without a pelvic examination or intraurethral swab specimen collection in men
• The false negative test results are due to amplification inhibitors and false positive results may be due to contamination of the sample
• Nucleic acid hybridization test (DNA probe test, molecular probe test):
• It is done on sample collected from endocervix (women) and urethra (men) to detect the nucleic acids of C.trachomatis
• The advantage of this test is that it is simple and inexpensive, with a sensitivity of about 85% and specificity of 98-99%
• The disadvantage being less sensitive in low prevalence populations (<5% infected) and false positive test results
• Serologic tests:
• These tests detect chlamydia antibodies by complement fixation (CF), microimmunofluorescence (MIF) and enzyme immunoassay (EIA) methods
• An elevated antibody titer from a blood specimen indicates recent chlamydia infection and useful in diagnosis of LGV, chlamydia pneumonia in infants and PID due to C. trachomatis
• The serological tests cannot differentiate among the species of Chlamydia and are not useful in acute genital tract infections
• Other tests:
• Giemsa staining of fixed smears are used to diagnose chlamydia conjunctivitis in newborns, but are not recommended in oculogenital infections in adults due to lack of sensitivity
• The leukocyte esterase (LE) test is a dipstick test performed on urine and detects an enzyme produced by polymorphonuclear cells (PMN), useful as a screening test in adolescent males. Sensitivities and specificities are highly variable as the presence of LE is present in a variety of infections
• Factors interfering with test results include:
• Pretest antimicrobial therapy
• Contamination due to fecal material on rectal specimens
• Improper collection techniques
• In men, voiding urine 1-3 hrs before the specimen collection
• In women, douching within 24 hrs prior to specimen collection
• Dried and refrigerated sample (for culture)
• Related laboratory tests include:
• C Reactive protein
• Complete blood count (CBC)
• Erythrocyte sedimentation rate (ESR)
• Sexually transmitted disease testing which includes:
• Gonorrhea
• Herpes
• Human immunodeficiency virus
• Human papilloma virus and genital warts
• Syphilis
• Trichomonas

Nl Result

• Chlamydia culture: No C. trachomatis organisms isolated
• Direct fluorescent antibody (DFA): Negative
• ELISA/Antigen assay: Negative
• Nucleic acid amplification tests (NAAT): Negative
• Nucleic acid hybridization test: Negative
• Serologic tests
• Complement fixation (CF): Negative
• Microimmunofluorescence (MIF): Negative

High Result

A positive result is consistent with presence of infection. Each technique has a false positive rate and the clinical scenario needs to be considered.

Low Result

A negative result is useful when screening low risk individuals. In cases where the clinical suspicion of chlamydial infection is high, the clinician should consider whether a negative result is a false negative.

References

• Agrawal T et al. Local Markers for Prediction of Women at Higher Risk of Developing Sequelae to Chlamydia trachomatis Infection. Am J Reprod Immunol. 2007 Feb;57(2):153-9.
• Caligaris LS et al. Trachoma prevalence and risk factors among preschool children in a central area of the city of Sao Paulo, Brazil. Ophthalmic Epidemiol. 2006 Dec;13(6):365-70.
• Centers for Disease Control: Screening Tests To Detect Chlamydia Trachomatis and Neisseria Gonorrhea Infections. MMWR October 18,2002/Vol.51/No.RR-15. [Homepage on the Internet]. Last reviewed on October 18, 2002. Last accessed on January 27, 2007. Available at URL: http://www.cdc.gov/mmwr/PDF/rr/rr5115.pdf
• Chen CY et al. The Molecular Diagnosis of Lymphogranuloma Venereum: Evaluation of a Real-Time Multiplex Polymerase Chain Reaction Test Using Rectal and Urethral Specimens. Sex Transm. 2006 Oct 25; [Epub ahead of print]
• Clad A et al. [Urogenital chlamydial infections in women and men.] [Article in German]. Hautarzt. 2007 Jan 6; [Epub ahead of print].
• eMedicine from WebMD®. Chlamydial Genitourinary Infections. [Homepage on the Internet] ©1996-2006. Last updated on June 29, 2006. Last accessed on January 27, 2007. Available at URL: http://www.emedicine.com/med/topic340.htm
• eMedicine from WebMD®. Trachoma. [Homepage on the Internet] ©1996-2006. Last updated onJanuary 8, 2007. Last accessed on January 27, 2007. Available at URL: http://www.emedicine.com/oph/topic118.htm
• Miller KE. Diagnosis and treatment of Chlamydia trachomatis infection. Am Fam Physician. 2006 Apr 15;73(8):1411-6. Available at URL: http://www.aafp.org/afp/20060415/1411.html
• Spagnoli LG et al. Persistent Chlamydia pneumoniae Infection of Cardiomyocytes Is Correlated with Fatal Myocardial Infarction. Am J Pathol. 2007 Jan;170(1):33-42.
• U.S. Preventive Services Task Force. Screening for Chlamydial Infection: Recommendations and Rationale. Article originally in Am J Prev Med 2001;20(3S):90-4. Agency for Healthcare Research and Quality, Rockville, MD. Last accessed on January 27, 2007. Available at URL: http://www.ahrq.gov/clinic/ajpmsuppl/chlarr.htm#tubes
• UTMB Laboratory Survival Guide®. CHLAMYDIA TRACHOMATIS AMPLIFIED ASSAY. [Homepage on the Internet]© 2006. Last reviewed on July 19, 2004. Last accessed on January 27, 2007. Available at URL: http://www.utmb.edu/lsg/LabSurvivalGuide/micro/CHLAMYDIA%20TRACHOMATIS%20DIRECT%20DNA%20PROBE.html
• UTMB Laboratory Survival Guide®. CHLAMYDIA TRACHOMATIS CULTURE. [Homepage on the Internet]© 2006. Last reviewed on July 20, 2004. Last accessed on January 27, 2007. Available at URL: http://www.utmb.edu/lsg/LabSurvivalGuide/micro/CHLAMYDIA%20TRACHOMATIS%20CULTURE.html