Implications of the variant strain of Chlamydia trachomatis (CT) circulating in Sweden

A CT variant (mutant) has been characterized by a 377 base pair deletion in the cryptic plasmid of 7501 bp in serovar E. Some NAATs target the plasmid: Roche Cobas Amplicor PCR/TaqMan 48, Abbott m-2000, and Becton Dickinson-ProbeTec. Other tests target other genes/targets and are not affected for detection: GenProbe Aptima targets the 16S rRNA gene, Artus-RealArt CT-PCR targets the omp-1 gene. Because of primer annealing location on the plasmid, both the Roche Cobas-Amplicor PCR/TaqMan 48 and the Abbott m-2000 will not identify the variant CT. Redesigning the primers to anneal to another plasmid-location would restore detection of the variant.