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Chlamydia Antigen
Aka: Chlamydia Antigen, Chlamydia Trachomatis Antigen, Chlamydia Polymerase Chain Reaction, Chlamydia Trachomatis PCR, Chlamydia PCR, Chlamydia Nucleic Acid Amplification Test, Chlamydia Trachomatis NAAT, Chlamydia DNA Probe, Chlamydia Rapid Point-Of-Care Test
- See Also
- Chlamydia trachomatis
- Indication
- Chlamydia screening in symptomatic and asymptomatic patients
- Background
- Chlamydia Antigen testing has replaced Chlamydia culture
- Nucleic Acid Amplification Tests (NAAT, PCR) are the primary tests used in the U.S. for Chlamydia detection
- Precautions
- Avoid rapid point-of-care Chlamydia tests (very low accuracy, see below)
- Labs
- Chlamydia Nucleic Acid Amplification Test (NAAT, PCR)
- Preferred method
- Older Methods
- Direct Fluorescent Antibody (DFA)
- Enzyme Immunoassay (EIA)
- Mechanism
- Detects both live and dead organisms
- Positive test may be seen in recent treatment
- Technique
- Same swab is used to detect both Gonorrhea and Chlamydia
- Eye Sample
- Topical Eye Anesthetic applied
- Swab lower and upper lids (inner surface)
- Urethral Samples (Males)
- Patient should not urinate within 1 hour before test
- Insert small Dacron swab 2-4 cm into Urethra
- Cervical Samples
- Wipe Cervix to remove excess mucus
- Insert Dacron swab into endocervix
- Rotate swab for 5 to 10 seconds
- Withdraw swabs without touching any vaginal surface
- Rectal Samples (symptomatic patients)
- Insert Dacron swab 3 cm into anal canal
- Withdraw swab
- Fecal contaminated samples should be redone
- Efficacy
- Chlamydia Nucleic Acid Amplification Tests (NAAT, PCR)
- Test Sensitivity: 85.5%
- Test Specificity: 99.6%
- Cook (2005) Ann Intern Med 142(11):914-25 +PMID: 15941699 [PubMed]
- Chlamydia DFA, EIA (older methods, replaced by PCR)
- Test Sensitivity: 88-91%
- Test Specificity: 97-99%
- Chlamydia Rapid Point-Of-Care Tests (avoid, very high False Negative Rate)
- Test Sensitivity: 38 to 58%
- Test Specificity: 98%
- Grillo-Ardila (2020) Cochrane Database Syst Rev (1):CD011708 +PMID: 31995238 [PubMed]