Chlamydia

Chlamydia, caused by Chlamydia trachomatis, is one of the 2 major causes of urethritis and cervicitis (the other is gonorrhea). It is frequently asymptomatic, which is why screening — not just symptom-triggered testing — is central to management. Untreated infection can ascend to cause pelvic inflammatory disease, ectopic pregnancy, and infertility, and can cause epididymitis in people with a penis. Because chlamydia and gonorrhea commonly co-occur, always assess for both when either is suspected.^[1]

• Sexually active and under 30 years of age — the group in whom opportunistic annual screening is recommended.
• New or multiple sexual partners.
• A sexual partner with confirmed or suspected chlamydia or gonorrhea.
• Inconsistent barrier protection.
• Pregnancy — universal screening is recommended regardless of other risk factors.

Testing

• NAAT is the test of choice. First-void urine or vaginal self-collected swab both perform well; clinician-collected cervical or vaginal swabs are also acceptable.
• Test extragenital sites (pharynx, rectum) when exposure history indicates — do not limit testing to genital sites based on assumption alone.
• If a rectal specimen is positive for chlamydia, test for lymphogranuloma venereum serovars — some laboratories trigger this automatically on a positive rectal result, others require a specific request.
• Because co-infection with gonorrhea is common, test for both whenever either is suspected, and screen for syphilis and HIV at the same visit.

• Eradicate C. trachomatis in the patient.
• Eradicate infection in all recent (under 60 days) sexual partners.
• Prevent ascending complications: pelvic inflammatory disease, epididymitis, ectopic pregnancy, infertility.
• Prevent vertical transmission when the patient is pregnant.

• Abstain from sexual intercourse for 7 days after starting adequate treatment, and until all sexual partners have also been treated.
• Refer all recent (under 60 days) sexual partners for testing and empiric treatment.
• Use barrier protection consistently going forward to reduce reinfection risk — reinfection rates are high enough that repeat screening at 6 months is routinely recommended (see Monitoring).

Children

In children 9-18 years, doxycycline is dosed at 5 mg/kg/day PO in divided doses (maximum 100 mg BID) for 7 days. Doxycycline is contraindicated in children 8 years and under. A confirmed diagnosis in a prepubertal child should prompt assessment for possible sexual abuse.

• Repeat screening is recommended for all treated patients 6 months after treatment, regardless of whether test-of-cure was performed — reinfection risk is high enough to warrant this routinely.^[3]
• Perform test-of-cure 3-4 weeks after completing therapy specifically when: the preferred regimen (doxycycline or azithromycin) was not used, symptoms persist, reinfection is suspected, adherence is in question, or the patient is a prepubertal child or is pregnant.
• Confirm partner treatment at follow-up — this is as important as confirming the patient's own treatment.

1. Confirm the regimen was completed correctly and on schedule.
2. Confirm all recent partners were tested and treated, and ask specifically about re-exposure.
3. Perform test-of-cure with NAAT (allow the recommended 3-4 week interval after treatment to avoid a false positive from residual nucleic acid).
4. If reinfection is excluded and nonadherence is excluded, treat with an alternative regimen from a different class (e.g., switch from doxycycline to azithromycin, or vice versa) rather than repeating the same drug.
5. Reassess for pelvic inflammatory disease or epididymitis if pelvic or scrotal pain has developed since initial treatment.

• Assuming a normal examination or absence of symptoms rules out infection — most chlamydia is asymptomatic.
• Using azithromycin for rectal infection when doxycycline is available and not contraindicated — doxycycline has a higher cure rate at this site.
• Using doxycycline in a pregnant or breastfeeding patient.
• Skipping the 6-month repeat screen because a test-of-cure was already done — these serve different purposes (cure versus reinfection).
• Treating the patient without arranging testing and empiric treatment for recent sexual partners.

How to use this table: Doses are adult doses unless a pediatric dose is stated, and require patient-specific confirmation. Treat sexual partners. Select any drug name to open its complete Pharmasist Drug Database page.

Tetracyclines

Preferred regimen for most patients; contraindicated in pregnancy, breastfeeding, and children 8 years and under.

Macrolides

Alternative regimen; preferred specifically in pregnancy and breastfeeding, and useful when adherence to a multiday course is a concern.

Penicillins

Second-line option specifically for use in pregnancy and breastfeeding.

Evidence note: Drug inventory, dosing, adverse effects, and comments reflect standard Canadian practice per current PHAC guidance.^[1]