Molecular Assays Detect New Chlamydia trachomatis Strain

Three assay systems have succeeded in detecting a mutant Chlamydia trachomatis strain, which shows a specific genetic variation (deletion) in the cryptic plasmid. The new strain was discovered last year in the Swedish County Hospital of Halmstad.

Qiagen (Hamburg, Germany;), a provider of sample and assay technologies for research in molecular diagnostics, applied testing, and life sciences, announced that the County Hospital in Halmstadt confirmed reliable detection of a new strain of the sexually transmitted bacterium C trachomatis using three of Qiagen's artus C trachomatis polymerase chain reaction (PCR) kits.

"All three PCR kits showed reliable detection of this new strain, as they target a region of the C trachomatis genome other than the deleted one in the mutant strain,” explained Dr. Tobias Ruckes, associate marketing director, molecular diagnostics, Qiagen. "With the artus C trachomatis Plus PCR kits, Qiagen provides the only test systems worldwide that detect a non-deleted region of the cryptic plasmid and, in addition, the genomic ompA gene. This dual target detection allows greatest specificity, sensitivity, and reliability.”

C trachomatis is the most common sexually transmitted bacterial pathogen causing infections in the mucous membranes of eyes, throat, or the genital area. If patients are not treated due to false-negative results, this may have severe consequences, including infertility in women. On average, one in 20 adults and one in 16 teenagers in Europe is infected.

In 2006, the Swedish Institute for Infectious Disease Control reported that sexually transmitted C trachomatis infections can no longer reliably be detected by conventional molecular diagnostic tests targeting the cryptic plasmid for detection. To assure reliable diagnostic results and to prevent spreading of the mutated strain, the Health Protection Agency in Great Britain recommends using assays detecting double target genes of the infectious agent in the same test reaction.

According to the latest research data, up to 40% of all C. trachomatis infections in some regions of Sweden are caused by the variant strain and it is unclear how long it has been circulating undiagnosed. Due to the high prevalence and because the genetic variant was not detected and treated, it may have already spread to other countries.

Dr. Torval Ripa, lab director, and Dr. Peter Nilsson, microbiologist of the Halmstad County Hospital, department of clinical microbiology and infection control, tested 10 clinical samples with the mutant C trachomatis strain using Qiagen's artus C trachomatis PCR kits. The results showed 100% reliability--all samples carrying the variant strain tested positive.

Qiagen's real-time (RT)-PCR kits for C trachomatis detection are highly sensitive diagnostic test systems that can be used in the early stages of Chlamydia infection. The artus C trachomatis PCR kit and artus C trachomatis plus PCR Kits are CE-marked for in-vitro diagnostic use in Europe. The kits are not yet available in the United States and Canada.


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