Which nucleic acid amplification tests (NAATs) are used in the workup of chlamydial genitourinary infections (chlamydia)?

Updated: Sep 25, 2018
  • Author: Shahab Qureshi, MD, FACP; Chief Editor: Michael Stuart Bronze, MD  more...
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The APTIMA Combo 2 Assay for ribosomal RNA (rRNA) can be used on ThinPrep liquid-based Pap smear specimens. [43] This has the advantage of being relatively simple and inexpensive. Most studies report sensitivities greater than 70% and specificities of 97-99% in populations of men and women with a prevalence of infection of 5% or more. If a definitive diagnostic test is required, antigen detection may well be the most appropriate diagnostic test for a primary care setting in the United States.

The main disadvantage of this approach is that it is less sensitive than tissue culture. In populations with a low (< 5%) prevalence of chlamydial infection, a highly significant percentage of positive test results are false positives. Accordingly, verification of a positive test result is desirable in certain cases. Such verification can be achieved by means of culture (eg, a second nonculture test that identifies a different chlamydial antigen or nucleic acid sequence from that identified in the first test), a blocking antibody, or a competitive probe.

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