Chlamydia TrachomatisInfection

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DESCRIPTION

Chlamydiae are obligate intracellular bacteria responsible for pulmonary infections, ocular disease, sexually transmitted infections (STIs), and infections of the genital tract in the pediatric and adult population.

  • The genus Chlamydophila has three species known to affect humans:
    • Chlamydia trachomatis
    • Chlamydophila psittaci
    • Chlamydophila pneumoniae
  • All three species can produce the clinical picture of the so-called atypical or interstitial pneumonia.
  • C. trachomatis can cause genital infections, lymphogranuloma venereum (LGV), trachoma, neonatal conjunctivitis, and pneumonia.
  • C. psittaci is mainly pathogenic for birds and occasionally affects humans, typically causing interstitial pneumonitis with associated fever, headache, malaise, and nausea.
  • C. pneumoniae causes pneumonia, pharyngitis, sinusitis, and bronchitis in humans.

EPIDEMIOLOGY

  • There are at least 18 serologically distinct variants with different associations:
    • A–C: trachoma
    • B, D–K: genital, oculogenital, and perinatal infection
    • L1–L3: LGV
  • C. trachomatis is the most frequent cause of epididymitis in sexually active young men.
  • Incubation period: at least 1 week for genital infection, 5 to 14 days after delivery for conjunctivitis, and 3 to 19 weeks for neonatal pneumonia
  • The possibility of sexual abuse should be considered in older infants and children with vaginal, urethral, or rectal C. trachomatis.

Incidence

  • C. trachomatis is the most common reportable STI in the United States with >1.8 million cases annually.
  • Most infections occur in individuals ≤24 years of age.
    • Rates of infection in adolescent girls are 15–20%.
  • 23–55% of all cases of nongonococcal urethritis in men are caused by C. trachomatis. Up to 50% of men with gonorrhea may be coinfected with C. trachomatis.
  • 50–75% of the neonates born to infected mothers via vaginal delivery will acquire C. trachomatis.
    • C. trachomatis infection can occur in infants delivered by cesarean section, even without rupture of amniotic membranes.
    • Of infants who became infected at birth, conjunctivitis may develop in 30–50% and pneumonia in 5–30%. The contagiousness of pulmonary disease is unknown but is considered low.
  • Ocular trachoma caused by serovars A, B, Ba, and C is the most common cause of preventable blindness in the world but is rare in the United States.
  • Rates among Black patients are 8 times that of White patients, followed by American Indians/Alaska natives (4.3 times) and Hispanics (2.7 times).

GENERAL PREVENTION

  • Annual chlamydia screening for all sexually active women aged <25 years, those at increased risk for infection (new sex partner, a sex partner with an STI, more than one sex partner or a sex partner with concurrent partners), and for all pregnant women in the first trimester of pregnancy is recommended. Pregnant women at increased risk for infection should be retested in the third trimester.
    • Adequate surveillance and treatment of C. trachomatis colonizing the genital tract of pregnant women is the best way of preventing disease in the infant.
  • Screening for men should be considered in certain high prevalence populations, including men who have sex with men (MSM), correctional facilities, or adolescent clinics.
    • MSM engaging in insertive or receptive anal intercourse should have urethral and rectal screening performed yearly; more often if multiple or anonymous sexual partners
  • Ocular prophylaxis at birth does not reliably prevent C. trachomatis conjunctivitis or extraocular infection, even if erythromycin ointment is used.

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