Chlamydia trachomatis inclusion bodies (brown) in a McCoy cell culture
The diagnosis of genital chlamydial infections evolved rapidly from the 1990s through 2006. Nucleic acid amplification tests (NAAT), such as polymerase chain reaction (PCR), transcription mediated amplification (TMA), and the DNA strand displacement amplification
(SDA) now are the mainstays. 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 they 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. 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.
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