Patient information

The reliability of laboratory tests for chlamydial infection

Following clinical examination, a specialist may make a presumptive diagnosis of non specific urethritis, cervicitis etc based on the signs or symptoms observed and their knowledge of the local situation. In poor areas of the world there may be few other tests available. A definite diagnosis of chlamydial involvement can only be made after laboratory tests have been performed to demonstrate the presence of the organisms themselves. Over the last decade laboratory tests for chlamydial infection have greatly improved (though there are still a lot of less good tests around, see below). Modern FDA-approved tests based on the detection and amplification of chlamydial genes are highly sensitive and specific. Such tests are relatively expensive and not all clinics have access to them. Furthermore the chlamydia may be present in extremely small amounts and may only be intermittently shed. Thus a negative test does not completely exclude the presence of chlamydial infection. If symptoms persist, don't hesitate to contact your doctor or clinic again. They may request further tests and put you on to alternative treatment.

Beware: Increasingly, a number of poorly regulated private companies / clinics offer testing for chlamydial genital tract infection. They may be using tests of inadequate sensitivity which, if negative, might give you a false sense of security. This particularly applies to Diagnostics.PointofCareTests based on the detection of chlamydial antigen.

Whoever is offering you chlamydia testing, find out if the test being offered is an FDA-approved test based on the amplification of chlamydial genes. "Good" FDA-approved tests include the Roche Amplicor, the GenProbe Aptima and the Becton Dickinson ProbeTecET.

For detailed information on laboratory testing see Diagnostics Index.

MeWard 2011

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Topic revision: r4 - 2011-04-16 - MeWard
 
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