Brief encounters
Discordant chlamydia
Nucleic acid amplification tests (NAAT) are very widely used in the diagnosis of Chlamydia trachomatis and can detect more cases than culture. The clinical and epidemiological significance of these additional cases is unclear. Rogers and colleagues looked at the concordance rates in partners of people with chlamydia. If the index case was NAAT positive but negative by traditional methods (culture and direct fluorescent antibody), 55% of partners were discordant (negative by both NAAT and traditional methods). If the index was positive by both NAAT and traditional methods then discordance fell to 25%. They also re-tested some NAAT positive cases prior to treatment and found that 17% were negative, indicating that infection may not be persistent. The authors conclude that this may be because a proportion of NAAT positive cases are of lower transmissibility and may be transient, although they argue strongly that these patients should be informed and treated. See …
