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Chlamydia
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All sexually active non pregnant women under 25 years of age should be screened opportunistically for chlamydia infection (A).
Those infected should be screened again after 6-12 months because of the high risk of re-infection. Male partners of infected females should be treated (A).
Men who have sex with men should be screened for chlamydia and other STIs every 12 months (B).
The U.S. Preventive Services Task Force (USPSTF) strongly recommends that clinicians routinely screen all sexually active women aged 25 years and younger, and other asymptomatic women at increased risk for infection, for chlamydial infection (see Clinical Considerations for discussion of risk factors). (A)
The USPSTF recommends that clinicians routinely screen all asymptomatic pregnant women aged 25 years and younger and others at increased risk for chlamydial infection (see Clinical Considerations for discussion of risk factors in pregnancy). (B)
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Clinical Considerations
- Women and adolescents through age 20 years are at highest risk for chlamydial infection, but most reported data indicate that infection is prevalent among women aged 20-25. Age is the most important risk marker. Other patient characteristics associated with a higher prevalence of infection include being unmarried.
- The optimal timing of screening in pregnancy is also uncertain. Screening early in pregnancy provides greater opportunities to improve pregnancy outcomes, including low birth weight and premature delivery; however, screening in the third trimester may be more effective at preventing transmission of chlamydial infection to the infant during birth. The incremental benefit of repeated screening is unknown.
- Screening high-risk young men is a clinical option. Until the advent of urine-based screening tests, routine screening of men was rarely performed.
- Partners of infected individuals should be tested and treated if infected or treated presumptively.
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Who is at higher risk?
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What should be done?
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How often?
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Increased Risk
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All sexually active women
under 25 years of age
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Urine microscopy and Culture and sensitivity
Serology test (IgG & IgM)
ELISA or LATEX test
Urine or endo-cervical swab for Ligase chain reaction (LCR) or polymerase chain reaction (PCR)
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Opportunistically
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High Risk
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All sexually active teenagers, particularly female, and
Those with pattern of inconsistent or no condom usage, or with recent change in sexual partner
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As above
(consider screening for other STIs)
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Every 12 months
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High Risk Men
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Men who have anal sex
with men
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Urine microscopy and Culture and sensitivity
Serology test (IgG & IgM)
ELISA or LATEX test
Urine for PCR and
Blind rectal swab for PCR
(consider screening for other STIs)
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At least every
12 months
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Sexual partners of infected women and men
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Test and treat immediately
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Every 12 months
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Intervention and Technique
PCR/LCR (site: Urine, endo-cervix, vagina)
- 20 mL first void urine (not mid stream) or at least 1 hour after last void. This has been found to be the best performing test in both sexes. Urine samples should be kept at under 4°C. Room temperature reduces sensitivity of LCR PCR endocervical or low vaginal swab (patient can self collect) also possible in females There has been no validation of this technique for anal or throat swabs
ELISA swab (site: Endo-cervix urethra)
- Inferior to PCR/LCR. Cheap, variable sensitivity and specificity, stores at room temperature
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