A variant of Chlamydia trachomatis with deletion in cryptic plasmid: implications for use of PCR diagnostic tests

Abstract

A new variant of Chlamydia trachomatis with a deletion in the cryptic plasmid has been detected in Sweden, following an unexpected 25% decrease in

Emergence and Spread ofChlamydia trachomatisVariant, Sweden

“…was discovered in Sweden (1). Because of a 377-bp deletion in the target sequence for amplifi cation, the variant had escaped detection by 2 widely used nucleic acid amplifi cation tests, Abbott m2000 (Abbott Laboratories, Abbott Park, IL, USA) and Cobas Amplicor/TaqMan48 (Roche Diagnostics, Basel, Switzerland) (1,2).…”

“…Because of a 377-bp deletion in the target sequence for amplifi cation, the variant had escaped detection by 2 widely used nucleic acid amplifi cation tests, Abbott m2000 (Abbott Laboratories, Abbott Park, IL, USA) and Cobas Amplicor/TaqMan48 (Roche Diagnostics, Basel, Switzerland) (1,2). The other test commonly used in Sweden, ProbeTec ET (Becton Dickinson [BD], Franklin Lakes, NJ, USA), detects the new variant because it uses a different DNA target sequence in the cryptic plasmid (3).…”

Diagnosis of Chlamydia trachomatis Infection

“…The Abbot RealTime CT m2000 PCR targets two parts of the cryptic plasmid [139]. All of these assays can successfully detect the new variant strain, first described in Sweden [140]. Despite very good performance by all these assays, the Gen-Probe assay seems to have superior sensitivity (99.3%) and equally good specificity (99.9%) as the Abbott m2000 assay.…”

Chlamydia trachomatis Infection and Reproductive Health Outcomes in Women

“…Transmission of C. trachomatis infection among the population can also be facilitated by the emergence of mutated strains, as occurred in Sweden in 2006 with the new variant of C. trachomatis (nvCT), which was not detected with the molecular techniques used in some regions due to a 377 bp deletion in the cryptic plasmid (74). The nvCT caused many falsenegative diagnoses, allowing this variant to spread to other northern European countries (91).…”

“…These new NAATs are able to detect variants with deletions in the cryptic plasmid such as the new Swedish C. trachomatis variant (nvCT), first detected in 2006. The nvCT variant contains a 377-bp deletion in the cryptic plasmid that covers the single targets originally utilized in some commercial NAATs (74). The use of modern automatic nucleic acid extraction devices also helps to improve the sensitivity of techniques that perform manual extraction through lysis (69).…”