Commercial NAATs for Chlamydia trachomatis achieve their high analytical sensitivity largely because the assay targets:
- A The approximately 7.5 kb cryptic plasmid present in multiple copies per organism ✓
- B The major outer membrane protein (ompA) gene, a single-copy chromosomal locus
- C 16S ribosomal RNA, which is degraded rapidly outside the host
- D The groEL heat shock protein gene expressed only during active infection
Correct answer: A. The approximately 7.5 kb cryptic plasmid present in multiple copies per organism
Explanation
Most widely used C. trachomatis NAAT platforms amplify sequences on the approximately 7.5 kilobase cryptic plasmid, which is carried by virtually all clinical strains in up to 7 to 10 copies per elementary body. Multiple target copies per organism give far greater analytical sensitivity than single-copy chromosomal genes such as ompA. Rare plasmid-free variants exist and prompted some platforms to add a second genomic target, but the multicopy plasmid remains the principal reason NAAT outperforms culture and antigen detection for this organism.
Reference: Jawetz, Melnick & Adelberg's Medical Microbiology, 28th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.