Chlamydia infection laboratory findings
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Aysha Anwar, M.B.B.S[2]
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Overview
Laboratory tests used in the diagnosis of chlamydia infection include nucleic acid amplification tests (NAAT) such as polymerase chain reaction (PCR), transcription mediated amplification (TMA), and the DNA strand displacement assay (SDA). NAAT for chlamydia infection may be performed on swab specimens sampled from the cervix (women) or urethra (men), on self-collected vaginal swabs, or on voided urine.[1][2][3]
Laboratory Findings
Laboratory findings consistent with the diagnosis of Chlamydial infection and its complications include:
| Type of Chlamydia | Tests | Findings | ||
|---|---|---|---|---|
| Neonatal Conjuctivitis | CBC | Normal | ||
| ESR | Normal | |||
| Neonatal pneumonia | CBC | Absolute increase in eosinophil count | ||
| ESR | increased | |||
| CRP | increased | |||
| Genital infection | CBC | increased leukocyte count | ||
| Urinalysis | >5 WBCS per high power field | |||
| ESR | normal or increased | |||
| CRP | normal or increased | |||
| Atypical pneumonia | CBC | Increased absolute eosinophil count | ||
Laboratory tests used in the diagnosis of chlamydia infection include nucleic acid amplification tests (NAAT) such as:
- Polymerase chain reaction (PCR)
- Transcription mediated amplification (TMA)
- DNA strand displacement amplification (SDA)
As of January 2007, the most commonly used and widely studied chlamydia NAATs in the US and many other industrialized countries are Aptima (Gen-Probe), Probe-Tec (Becton-Dickinson), and Amplicor (Roche). The Aptima Combo II assay tests simltaneously for C. trachomatis and Neisseria gonorrhoeae, the cause of gonorrhea. NAAT for chlamydia may be performed on swab specimens collected from the cervix (women) or urethra (men), on self-collected vaginal swabs, or on voided urine. Urine and self-collected swab testing facilitates the performance of screening tests in settings where genital examination is impractical.
At present, the NAATs have regulatory approval only for testing urogenital specimens, although rapidly evolving research indicates that the Aptima test may give reliable results on rectal specimens.
Because of improved test accuracy, ease of specimen management, convenience in specimen management, and ease of screening sexually active men and women, the NAATs have largely replaced culture, the historic gold standard for chlamydia diagnosis, and the non-amplified probe tests, such as Pace II (Gen-Probe). The latter test is relatively insensitive, successfully detecting only 60-80% of infections in asymptomatic women, and often giving falsely positive results. Culture remains useful in selected circumstances and is currently the only assay approved for testing non-genital specimens.
References
- ↑ Peipert JF (2003). "Clinical practice. Genital chlamydial infections". N Engl J Med. 349 (25): 2424–30. doi:10.1056/NEJMcp030542. PMID 14681509.
- ↑ Enwemeka CS, Rodriguez O, Mendosa S (1990). "The biomechanical effects of low-intensity ultrasound on healing tendons". Ultrasound Med Biol. 16 (8): 801–7. PMID 2095010.
- ↑ Centers for Disease Control and Prevention (2014). "Recommendations for the laboratory-based detection of Chlamydia trachomatis and Neisseria gonorrhoeae--2014". MMWR Recomm Rep. 63 (RR-02): 1–19. PMC 4047970. PMID 24622331.