Infectious Diseases & Sexual Health
Chlamydia
Chlamydia — caused by the bacterium Chlamydia trachomatis — is the most common bacterial sexually transmitted and blood-borne infection (STBBI) in Canada and Quebec. With over 30,000 new cases reported annually in Canada (and an actual number estimated to be 3 to 5 times higher due to insufficient screening), it affects all sexually active populations, with a peak incidence in young adults aged 15 to 24, who represent over 60 % of reported cases. Chlamydia trachomatis is an obligate intracellular bacterium - it can only reproduce within the host's epithelial cells - which explains its predilection for the columnar epithelia of the endocervix, urethra, rectum, pharynx and conjunctiva, as well as its natural resistance to most antibiotics acting on the bacterial wall (beta-lactams). The most deceptive and dangerous clinical feature of this infection is its massively asymptomatic nature: 70 to 80 % of infected women and 50 % of infected men show no symptoms, unknowingly transmitting the infection to their partners and exposing women to the most dreaded silent complications - pelvic inflammatory disease (PID), responsible for tubal infertility, ectopic pregnancy and chronic pelvic pain. Mandatory reporting of chlamydia has been in force in Quebec since 1990, and the Canadian STBBI Guidelines (updated 2021) recommend systematic annual screening for all sexually active women under 25 years of age and for those with risk factors, regardless of the presence of symptoms.
Microbiology and transmission
- Chlamydia trachomatis — Serotypes and diseases: Serotypes D through K (most common in North America) — genital, rectal, pharyngeal, and conjunctival infections transmitted sexually; Serotypes L1, L2, L2a, L2b, L3 — lymphogranuloma venereum (LGV — a severe genital ulcerative disease and hemorrhagic proctitis, more common in men who have sex with men — MSM); Serotypes A, B, Ba, C — endemic ocular trachoma (leading global cause of preventable blindness — developing countries; not sexually transmitted)
- Sexual transmission: direct mucous membrane contact with genital, rectal, or pharyngeal secretions from an infected person — unprotected vaginal, anal, or oral-genital intercourse; condoms, when used correctly and consistently, reduce the risk of transmission by 50-90% %; no transmission via inanimate objects (toilets, doorknobs) outside of sexual practices
- Vertical transmission (mother-to-child): during passage through the infected birth canal — neonatal chlamydial conjunctivitis (neonatal ophthalmia — onset 5 to 14 days after birth, to be distinguished from earlier-onset neonatal gonococcal ophthalmia [1 to 5 days]) and infantile chlamydial pneumonia (age 1 to 3 months — afebrile pneumonia with characteristic staccato cough).
- Incubation period: 7 to 21 days after infectious contact — time before symptom onset (if symptoms occur); the bacteria can persist for months to years without treatment
Symptoms
| Population / Site | Clinical manifestations |
|---|---|
| Female (genital) | Asymptomatic in 70–80 % of cases — mucopurulent cervicitis (yellowish vaginal discharge, friable and hemorrhagic cervix on examination); dysuria (burning urination); intermenstrual or postcoital metrorrhagia; lower pelvic pain; intermenstrual spotting |
| Male (genital) | Asymptomatique dans 50 % des cas — urétrite (écoulement urétral clair à blanc, brûlures mictionnelles, prurit urétral) ; épididymite aiguë (douleur et gonflement d'un testicule — unilatérale, peut mimer une torsion testiculaire) ; prostatite aiguë (douleurs pelviennes, troubles urinaires, fièvre) |
| Man and woman (rectal) | Mild proctitis — anal pruritus, tenesmus, mild rectal pain, mucoid rectal discharge; often asymptomatic; LGV: severe hemorrhagic proctitis, intense rectal pain, bleeding, constipation, fever — pseudo-inflammatory picture (rectal Crohn's) |
| Pharyngeal | Almost constantly asymptomatic — mild pharyngitis possible; transmission reservoir not recognized |
| Conjunctival | Unilateral or bilateral follicular conjunctivitis — purulent ocular discharge, conjunctival hyperemia, mild photophobia; can spread by autoinoculation (fingers) from an active genital infection |
| Infant (vertical) | Neonatal conjunctivitis (J5–J14) — bilateral purulent ocular discharge; infantile pneumonia (1–3 months) — staccato cough (dry, repetitive bouts), tachypnea, absence of fever, bilateral interstitial infiltrates on radiography |
Complications
- Maladie inflammatoire pelvienne (MIP) chez la femme : ascension bactérienne de l'endocol vers l'utérus (endométrite), les trompes (salpingite), les ovaires et le péritoine pelvien — cause principale d'infertilité tubaire acquise (obstruction des trompes par fibrose post-infectieuse), de grossesse ectopique (risque multiplié par 6 à 10 après une MIP) et de douleurs pelviennes chroniques ; la MIP peut être sub-clinique (silent PID) dans 50 % des cas — sans douleur pelvienne franche mais avec des séquelles tubaires identiques ; syndrome de Fitz-Hugh-Curtis : périhépatite par extension de l'inflammation pelvienne au péritoine hépatique — douleur de l'hypochondre droit aiguë chez une femme jeune, souvent confondue avec une cholécystite ou une pleurésie
- Infertilité tubaire : le risque d'infertilité augmente avec le nombre d'épisodes de MIP — 11 % après un épisode, 23 % après deux épisodes, 54 % après trois épisodes ; les anticorps anti-HSP60 de Chlamydia trachomatis correlate with the degree of tubal damage
- Epididymo-orchitis in men: unilateral testicular pain and swelling of the epididymis — main risk of male infertility due to epididymal obstruction if untreated; obstructive azoospermia possible after repeated episodes
- Reactive arthritis (Fiessinger-Leroy-Reiter syndrome): post-infectious reactive aseptic arthritis — classic triad: non-gonococcal urethritis + asymmetrical large joint arthritis + conjunctivitis/uveitis; HLA-B27 association; occurs 1 to 4 weeks after genital infection; predominantly affects young men; self-limiting in 3 to 6 months but relapses possible
- Lymphogranuloma venereum (LGV — serotypes L): primary phase (transient, painless genital ulcer, often unrecognized); secondary phase (inflammatory bilateral inguinal lymphadenopathy with fistulization — buboes — or severe hemorrhagic proctitis in MSM); untreated tertiary phase: genital elephantiasis, rectal stenosis, anorectal fistulas
- Increased risk of HIV co-infection: genital inflammation caused by chlamydia increases susceptibility to HIV acquisition by 2 to 5 times by increasing local recruitment of target cells (CD4 lymphocytes) and altering mucosal integrity
ℹ️
In Quebec, the Canadian Guidelines on STIs recommend annual screening for chlamydia (and gonorrhea) in all sexually active women under 25 years old, regardless of the number of partners and even in the absence of symptoms. Screening is done via a simple endocervical or vaginal swab (vaginal self-swab accepted) or by urinalysis (first-void urine) – quick, painless, and reliable by PCR. A positive test is a mandatory report in Quebec, and partners from the last 60 days (or the last partner if the period is > 60 days) must be screened and treated.
Screening — who to screen and how
- Sexually active women under 25: annual screening recommended by the 2021 LHDIs, regardless of the number of partners or presence of symptoms; screening every 3 to 6 months if multiple partners or other risk factors
- Women aged 25 and over: screening recommended if new partner or multiple partners in the last year, partner with known STIs, suggestive symptoms (discharge, pelvic pain, metrorrhagia), history of STIs, pregnancy (screening in the 1st trimester recommended)
- Men: screening recommended if symptoms (urethritis, epididymitis), multiple partners, MSM (screening every 3 to 6 months urethral + rectal + pharyngeal depending on sexual practices), diagnosed partner, history of STIs
- HARSAH: multisite screening recommended every 3 to 6 months — urethra (first void urine), rectum (self-collected or medical rectal swab), pharynx (throat swab) according to reported practices; include LGV screening on any rectal swab positive for Chlamydia trachomatis
- Preferred screening technique: nucleic acid amplification test (NAAT / PCR) — gold standard; sensitivity > 97 %, specificity > 99 %; specimens: first-void urine (male & female), vaginal self-collection (female — as sensitive as endocervical swab), endocervical swab (during pelvic exam), rectal swab, pharyngeal swab; urine NAAT is insufficiently sensitive for rectal and pharyngeal screening — specific swabs required for these sites
Treatment
- Uncomplicated genital chlamydia (urethritis, cervicitis, mild rectal infection) - 2024 standard treatment: doxycycline 100 mg orally twice daily × 7 days - first-line treatment according to the 2021 revised LDCI (superior to single-dose azithromycin for rectal infections and infections with Chlamydia trachomatis with high bacterial load); azithromycin 1 g orally as a single dose - alternative if adherence to 7-day treatment is uncertain or patient preference (directly observed therapy possible in clinic); levofloxacin 500 mg orally once daily × 7 days - alternative in case of contraindication to the first two
- Pregnancy: azithromycin 1 g orally single dose — standard treatment in pregnancy (doxycycline contraindicated in the 2nd and 3rd trimesters); amoxicillin 500 mg orally 3 times a day × 7 days — alternative; test of cure recommended in pregnant women 3–4 weeks post-treatment; systematic screening in the 3rd trimester if risk factors
- LGV (serotypes L): doxycycline 100 mg orally twice a day × 21 days – reference treatment; erythromycin 500 mg four times a day × 21 days – alternative in pregnancy; drainage of fluctuating inguinal buboes by aspiration (surgical incision not recommended – risk of fistulization)
- PID (pelvic inflammatory disease): outpatient treatment for mild to moderate forms - ceftriaxone 500 mg IM single dose + doxycycline 100 mg twice daily × 14 days + metronidazole 500 mg twice daily × 14 days (anaerobic coverage); hospitalization for severe forms (high fever, tubo-ovarian abscess, pregnancy, immunocompromised, no improvement after 72 hours of oral treatment) - IV ampicillin-sulbactam or IV cefotetan + IV doxycycline; total duration 14 days
- Chlamydia epididymitis: ceftriaxone 500 mg IM single dose + doxycycline 100 mg twice daily × 10 days; scrotal support, NSAIDs for pain
- Neonatal conjunctivitis and infant pneumonia: erythromycin 12.5 mg/kg orally 4 times a day × 14 days - pediatric standard of care; azithromycin 20 mg/kg/day × 3 days - alternative
- Notification and partner management: all sexual partners within the last 60 days should be screened and treated empirically (even if asymptomatic and before results); if last intercourse > 60 days ago, treat the last known sexual partner; sexual abstinence (or condom use) for 7 days of treatment and until symptoms resolve in both partners; test-of-cure is not routinely recommended for non-pregnant individuals if treatment is completed and symptoms have resolved — except in pregnant women, in case of persistent symptoms, suspected non-adherence, or exposure to an untreated partner; re-screening at 3 months is recommended due to the high risk of reinfection
Signs requiring immediate medical attention
Consult a doctor promptly (within 24-48 hours) if you experience female pelvic pain with fever, unusual vaginal discharge associated with lower abdominal pain, unilateral testicular pain with swelling, or if you have been informed that a partner has been diagnosed with chlamydia—even in the absence of symptoms. Untreated pelvic inflammatory disease can cause permanent infertility within days to weeks of onset. For all STI screening, sexual health consultations, or treatment, Clinique Omicron offers confidential consultations at our Quebec locations as well as telemedicine. To book an appointment, visit cliniqueomicron.ca.
Consult at Clinique Omicron
Clinique Omicron offers comprehensive sexual health services, including STI testing via NAAT (PCR) for chlamydia, gonorrhea, HIV, syphilis, and hepatitis, prescription of appropriate treatment, assisted partner notification, and post-treatment follow-up. Confidential consultations are available at our Quebec locations and via telemedicine throughout the province. To book an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not replace the advice of a qualified healthcare professional. Chlamydia is a reportable infection in Quebec. Any positive result must be reported to the Public Health Department.
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