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Source: Knodel LC. Sexually Transmitted Diseases. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th edition. Accessed July 16, 2012.

  • Sexually transmitted infection (STI)

  • C. trachomatis is an obligate intracellular parasite with some similarities to viruses and bacteria.

  • Requires cellular material from host cells for replication.
  • Maintains cellular identity throughout development.
  • Frequent coinfection with gonorrhea.

  • Most common STI in the United States

  • Mutually monogamous sexual relationship between uninfected partners
  • Barrier contraceptive methods

  • Patients who seek STI testing should be screened for syphilis and HIV.
  • Annual screening recommended by CDC for sexually active females:
    • 25 years of age or younger
    • With new sex partners or multiple sex partners

  • Unprotected sex
  • Number of sexual partners
  • Sexual preference
  • Age: Two-thirds of STIs occur in persons in their teens and twenties.

  • Chlamydial genital infections more frequently asymptomatic, and when present, symptoms tend to be less noticeable (Table 1).
  • Nearly two-thirds of infants acquire chlamydial infection after endocervical exposure, with primary morbidity associated with seeding of infant’s eyes, nasopharynx, rectum, or vagina.

Table 1. Presentation of Chlamydia Infections

Signs and Symptoms

Means of Confirmation and Diagnosis

  • Cell culture is reference standard but 3- to 7-day delay in results has led to use of tests that rapidly detect chlamydial antigens and nucleic acid.

Laboratory Tests

  • Culture of endocervical or urethral epithelial cell scrapings
    • Most specific method (close to 100%)
    • Sensitivity is as low as 70%.
    • Results available in 3–7 days.
  • Non-culture tests:
    • Enzyme immunosorbent assay (EIA), DNA hybridization, nucleic acid amplification tests (NAATs)
      • Allow rapid identification of chlamydial antigens and nucleic acid.
      • Technically less demanding
      • Less costly, and in some situations have greater ...

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