Chlamydial Sexually Transmitted Diseases
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- An intracellular membrane-bound prokaryotic organism, Chlamydia trachomatis is the most common bacterial STI in the US.
- Transmitted through vaginal, anal, or oral sex; may also occur vertically from mother to infant during vaginal birth
- Most common bacterial sexually transmitted disease reported to the CDC (1).
- Majority of cases are asymptomatic, especially in females. Untreated disease can lead to pelvic inflammatory disease (PID), ectopic pregnancy, infertility.
- System(s) affected: Reproductive
Perinatal acquisition may result in neonatal pneumonia and/or conjunctivitis.
- Mandatory reporting started in 1985, with data showing steady increase in incidence since.
- 1.4 million reported cases in 2011. Increasing incidence reflects greater screening, improved testing modalities, and better reporting rather than a large increase in disease burden.
- Swedish new variant chlamydia (nvCT) was first reported in 2006; often produces false-negative tests; largely confined to Nordic countries (2). Sensitive testing of 473 samples from around the US found none of the variants.
- 457.6/100,000 people in the US in 2011
- Populations most affected: Young females, particularly those of ethnic minority groups
- Peak incidence: Age 18–20
- Predominant sex: Females > Males. Females have >2.5 × higher reported incidence and prevalence than males, but this likely reflects increased testing in females. Increasing use of urine screening may increase screening in males.
- Minorities bear the highest burden, with infection rates among blacks in >7 × that of whites. Rates higher in larger, more metropolitan areas.
- Highest prevalence for males is in heterosexual adolescents
Etiology and Pathophysiology
C. trachomatis serotypes D–K
Risk correlates with:
- Number of lifetime sexual partners and number of concurrent sexual partners
- Lack of barrier contraception during sexual intercourse
- Younger age (highest in females 15–19 years, males 20–24 years)
- Black/Hispanic/Native American and Alaskan Native ethnicity
- Populations with prevalence >5% should be screened at least annually (1). Screen if: New or >1 sex partner in past 6 months, attending an adolescent or family-planning clinic or STD or abortion clinic, attending a jail or other detention-center clinic, rectal pain, discharge or tenesmus, testicular pain; test any individual with urethral or cervical discharge.
- All sexually active women ≤25 years of age should be screened at least yearly, and repeat testing in ∼3months is recommended for those who screen positive, because reinfection rate is high regardless of whether the sexual partner is treated(3)[A].
- Screening sexually active men ≤25 years is controversial but should be strongly considered in high-risk populations.
- Annual screening is recommended for men who have sex with men; this may include, as appropriate, rectal nucleic acid amplification test (NAAT) and/or urethral (urine) testing.
Commonly Associated Conditions
- Pelvic inflammatory disease (PID): ∼10% of women with positive chlamydia screen developed PID within 12 months (4).
- Infertility and ectopic pregnancies
- Chronic pelvic pain
- Mucopurulent cervicitis with cervical edema and propensity to bleed during speculum exam
- Urethral syndrome (dysuria, frequency, and pyuria in the absence of infection with uropathogen)
- Arthritis (rare)
- Spontaneous abortion (5)
- Epididymitis and nongonococcal urethritis
- Reiter syndrome (HLA-B27)
- Inclusion conjunctivitis (occurs in ∼40% of exposed neonates) (3)
- Otitis media
- Diseases caused by other chlamydial species:
- Lymphogranuloma venereum: C. trachomatis serotypes L1–L3
- Trachoma: C. trachomatis serotypes A–C