Update on the new variant of Chlamydia trachomatis: Prevalence and diagnostics

In 2006, a new variant of Chlamydia trachomatis (nvCT) was discovered in Sweden [1]. Due to a deletion in the target sequence for PCR amplification, nvCT has escaped detection by the nucleic acid amplification tests Abbott m2000 (Abbott Laboratories) and Cobas Amplicor/TaqMan48 (Roche Diagnostics) which together were used for 65% of all chlamydia tests in Sweden. The third test commonly used in Sweden, ProbeTec ET (Becton Dickinson [BD]), does detect the new variant because it uses a different DNA target sequence in the cryptic plasmid. The nvCT is spread all over Sweden and in early 2007, it accounted for between 20% and 65% of all chlamydia cases in Swedish counties where Abbott/Roche test systems were used [2]. In the four counties that used the BD system, the proportion of nvCT was only between 7% and 20% in the same time period. Ongoing studies are now following the spread of the nvCT in several counties.