Detection of Chlamydia trachomatis by DNA Amplification

The Chlamydiae are small, nonmotile Gram-negative bacteria that were originally thought to be viruses because of their size and their obligate dependence on host cells for growth. They are characterized by a unique biphasic developmental cycle involving an interconversion between the extracellular, infectious but metabolically inactive elementary body form (EB) and the intracellular, metabolically active but noninfectious reticulate body form (RB). Within an infected cell, the reticulate bodies multiply 200–500-fold by binary fission, resulting in a characteristic chlamydial inclusion, that often distends the cell. Of the four currently recognized chlamydial species (although et al. [1 ] recently proposed a split of the Chlamydiae into two genera and nine species) only Chlamydia trachomatis and C. pneumoniae are common pathogens of humans. C. trachomatis is the more important pathogen of the two species for humans and it infects the mucosal surfaces of the cervix, urethra, rectum, nasopharynx, and conjunctiva. Cervical infections can ascend into the endometrium and the fallopian tubes, resulting in pelvic inflammatory disease, infertility, and ectopic pregnancy. Infection during pregnancy can adversely affect the newborn, leading to neonatal conjunctivitis and infant pneumonia. In males, C. trachomatis is a major cause of nongonococcal urethritis and ascending infections can lead to epididymitis. C. trachomatis infections are recognized worldwide as the most common bacterial sexually transmitted disease, and it is estimated that more than 50 million new cases of C. trachomatis infection occur annually (2 ).